Capsize Screening Formula
Joe Ozelis
Jim Manzari wrote :
> Joe Ozelis wrote:
> >
> > On Sun, 22 Mar 1998, Jim Manzari wrote:
> > > In contrast, the modern
> > > Mumm 30 class boat is said to be "a disaster waiting to happen". All
> > > it needs is another "bomb" storm like the 1979 Fastnet.
> >
> > Please cite your reference. And your experiences sailing the Mumm 30.
> > I have not heard this from any (responsible) party. While sailign a
> > Mumm 30 in a 1979-like Fastnet race would certainly be no picnic, there
> > is no evidence that it would not be able to survice such an event.
>
> I think you meant to say "survive" not "survice" such an event. On
> the basis of that assumption please consider the following:
Very impressive - begin your reply by nit-picking a typo. Very mature.
>
> I am pretty certain I am not the first or only person to hold an
> opinion (pro or con) about the Mumm class. In fact, this is not the
> first time in this thread that the Mumm class has been mentioned using
> these exact words, in the context of capsize screening.
So that makes it OK for you to repeat the (mis)information, without making
any effort to determine it's veracity ? Yet you continually bombard
pariticipants in these discussions with both immaterial and tangential
refrerences in an effort to bolster your position, as if a bloated
bibliography lent any credence to your position.
>
> Having said that, I am sorry if your Mumm has been unnecessarily
> caught up in this controversy. It is inevitable that this type of
> boat should be mentioned in the context of capsize risk and the
> Fastnet, as they are one of the most numerous classes in the now
> canceled Fastnet Race.
???? Now we know you really don't know what you are talking about
as far as race boats are concerned. The Mumm 30 (topic of the afore-
mentioned exchange) has NEVER raced in the Fastnet race. Perhaps you
are confusing it with the Mumm36, which is the small boat one design
presently in the Admiral's Cup ??
> On the bright side, they will race in the Wolf
> Rock race, which is the replacement for the Fastnet and will be run
> entirely within the English Channel -- no open sea areas as in the
> Western Approaches and Fastnet -- plenty ports of refuge in the event
> of bad weather. This should considerably reduce rescue costs for all
> classes, in my opinion.
>
How wonderfully partonizing of you. I'm sure the RORC is appreciative
of your concerns.
> For reference material regarding the Mumm class and the Fastnet you
> might want to look at the January 1998 issue of the UK magazine
> "Yachting World" for an editorial comment by Andrew Preece, the
Ummm - I prefer to get my information directly form the people I know
personally who are sailing the boats in these events...
Obviously since your experience sailing on any modern IMS (or even IOR)
racing design is limited-to-non-existant, you must rely upon others to
form your opinions. It's too bad you are unable or incabale of objectively
evaluating these opinions. Otherwise you would not have been so confused
by the Mumm30/Mumm36 distinction.
< irrelevant reference to sensational Economist article snipped>
> What's at issue in this newsgroup discussion is the unsuitability of
> racing yachts for long-term offshore cruising by short-handed,
> non-professional crew. Nothing more. I am sure you would never
> recommend your Mumms for long-term world-wide offshore cruising.
No - but for reasons other than safety. Storage, interior room, and
accomodations issues would preclude the use of such a boat for extended
cruising. Converseyl, I would never bas a reccomendation solely on a
one-dimensional arbitrary formula that has not achieved general acceptance
among the indsutry.
> You could help settle this controversy, since you sell both Island
> Packet (generally recognized as very capable and seaworthy offshore
> cruising yachts) and the Mumm boats (presumably fine racing boats):
> publish the righting moment curves for the two types of boats on your
> sales Web site and in your sales brochures. Show the area under the
> positive and negative curve for these two types of boats. It would be
> a great help in settling this matter.
This information is already available from the manufacturers. In comparing
it, you must keep in mind that it is generated "in-house" (unless taken
from an IMS certificate which utilizes the ORC IMS hydrostatics calculation
module) - and different design firms will utilize different VPP's or design
programs (MaxSurf, etc.) to calculate these values. Additionally, as has
already been noted by others, the ultimate LPS, Stability Index, and ratio
of stabiltiy curves, are affected by deck superstructure, etc., which is
not generally taken into acount by these programs. You might also find it
surprsing that many modern IMS designs are exceedingly stable (high LPS)
and have high stablity curve ratios.
> The boating industry, of which you are a part, could help resolve many
> concerns about stability and seaworthiness of racer, racer/cruiser,
> and the so-called "performance" cruisers.
...snip...
> Another result your industry might want to publish is the number of
> minutes each model of boat remains in a stable inverted position
> before coming back upright. The inverted test should include data for
> various inverted angles and with various amounts of water intake via
> vents and other normal openings.
>
You relize, of course that many of these studies would require immense
finacial investment, that no single manufacturer, nor even the industry
as a whole, could afford to provide. This data must be acquired empirically,
by performing flotation measuremnts on actual designs, throghout the
parameter space of interest. Unless individual sailors such as yourself
wish to fund this exercise, it seems rather improbable that it can be
performed in any meaningful way. The sailing industry is not, as a rule,
blessed with high profit margins and excessive amounts of liquid (no pun
intended) capital.
Interstingly, much of the research on such topics that has been performed
to date was under the auspices of Mr. Kirkman, the IMS Technical Committee,
the ORC, local PHRF racing organizations, and the US Sailing Asociation -
all racing organizations !
> See also the Yachting World Exclusive called "A Survivor's Story",
> September 1997. The story tells of 3 men (2 of whom died) due to
> capsize in gale conditions in the tide race off the Needles Channel at
> the entrance to the Solent. The lone survivor states:
>
> "The first time the boat capsized it rolled over 180-degrees and
> remained upside-down for about 30 seconds...There was approximately
> 3-4ft of water inside the boat...The boat remained upright for one to
> two minutes when it again capsized to 180-degrees and again remained
> totally upside-down. The boat was in this state for between five and
> ten minutes..."
>
I note that you provide no information as to the type of baot, the level
of experience of the crew, nor the qantitative effect on rigthing moment
due to " 3-4ft of water inside the boat " - the latter two being indepedant
of design, and having a substanital effect on the outcome of the situation.
> In the September 1997 issue of Yachting World, the editor Andrew Bray,
> made the following comments on his editorial page:
>
> "A few weeks ago I read, with disbelief, an account of one of the
> RORC's major offshore races, the De Guingand Bowl.
...snip...
> But no,
> two thirds of the fleet retired, mostly undamaged. Are we now
> reaching the stage with ocean racing when crews pull out as soon as it
> gets uncomfortable?
Doesn't this simply say that today people race primarily for fun and
enjoyment, and not some machismo-induced man-against-the-sea testoterone-
building contest ? If participating in a given event is not fun, people
will withdraw. Conditions in which it is very unpleasant aboard a racing
yacht will be equally unpleasant in any reasonably-sized offshore cruiser.
I began my big boat racing career on CCA-era designed yachts, which more
closely fit your definition of acceptable offshore cruiser - and going to
weather in them with 35kts of breeze was equally uncomfortable as on today's
racing yachts - just a lot slower, prolonging the agony.
Beating to windward in 35kts+ is not fun, unless you are on an aircraft
carrier.
> It is worth pondering that a husband and wife crewing their boat
> between, say Falmouth and Gibraltar or the Chesapeake and Bermuda, in
> these same conditions do not have the luxury of "retiring" from the
> cruise.
But they do have the luxury of altering course or heaving-to in order to
ameliorate the conditions on board - while the racer is constrained by the
race course to proceed on a perhaps more unfavorable point of sail. Unless,
of course, the cruiser finds himself having to beat off a leeward shore,
in which case he will envy the racer's superlative VMG and pointing ability.
> Which libel and slander definitions would you like me to review?
> Illinois state definitions? British? Swiss?
Actually, as Usenet is an international medium, the laws of each apply in
their own manner, and in their own jurisdiction.
> Why is it some of you
> racing fellows feel the need to resort to threats and rudeness?
I see nothing threatening or rude in my asking you to support your baseless
allegations disparging the safety of a product.
> Why
> are you so sensitive to open discussion of anything negative regarding
> racing boats in the context of their application to cruising?
As long as the discussion is rooted in fact and experience, not hearsay,
the blind application of a not-universally-accepted first-order metric,
or non-peer reviewed data and analysis, I'm sure we have no problem with
it.
You might find it interesting to note that, in agreement with what you
have been told by Mssrs. Kamen and Schell, the work of Mr. Marchaj is
not part of any foundation of naval architecture studies nor widely
accepted or utilized by those in the profession. My source for this is two
close friends of mine, both graduates of the Unversity of Michigan's
Naval Architecture degree program, along with their classmates Bruce
Nelson, John Reichel, and Bill Tripp.
> Why are
> you even discussing this in a newsgroup chartered to be a cruising
> discussion group?
>
Because older race boats can be and are utilized for offshore cruising,
and are therfore a suitbale topic of a cruising newsroup.
> > You may also find it of interest that a single-handed J-30 was caught
> > in the Fastnet storm of 1979, and survived unscathed.
>
> Unscathed? Well, Joe, you didn't quite tell the complete story here.
> The "rest of the story" is that Bill Wallace, who can sometimes be
> found in various mailing lists devoted to cruising on the Internet and
> a man who commands great respect from other cruising skippers, was...
>
> "...90 nautical miles further south than the center of the 40 mile
> circle in which so many Fastnet race yachts suffered damage... his
> <boat> was rolled down only once, to 120 degrees...and flying tin cans
> cut his scalp...Wallace also reported that the night never darken.
> 'By nightfall in the middle of the gale, the stars were out, then the
> moon came up.' The only light that many Fastnet race crews saw
> was that from a flare..."
>
I am well aware of Mr. Wallace's contributions to the Yacht-L mailing
list, and he also lives in my neck of the woods. I've heard his personal
account of the events, I do not need Mr. Rousmaniere's opinions and
narrative inclusions.
Furthermore, I am well acquanted with Mr. Rousmaniere's book - I have a
well-thumbed copy at home. So I'm (not) surprised that you fail to
include Chris Bouzaid's account (p. 154) of how increasing the speed of
his boat Police Car helped to ease their discomfort and improve their
control, or how the crew of the Maitenes II (hardly an example of a
modern or even IOR-era racing yacht!) competing in the 1931 Fastnet race
feared their yacht would be pooped and sink, and required rescue (pp.
163-165). Nor did you make mention that many of the Fastnet "survivors"
believed it was crew (in)experience, rather than boat design, that led
to unfortunate occurences (pp. 226, 232, 236). Nor do you make mention
of the fact that a higher percentage of the Admiral's Cup yachts
(representing to most race-oriented, stripped out designs) finished than
the Fastnet fleet as a whole, nor that the subesequent inquiry did not
find a causal relationship between boat design and degree of casualties.
> John Rousmaniere
...snip...
is the editor of "Desirable and Undesirable
> Characteristics of Offshore Yachts"
and has also developed a cottage industry by preaching of the
"unseaworthiness" of modern yachts, equipment, and techniques, while
offering no evidence to support his claim. If your only experience with
modern racing yachts in diffcult conditions is that provide by Mr.
Rousamniere, you have a limited and subjective perspective, indeed.
> What some racers don't seem to understand is that there are many
> long-term offshore cruisers who dislike the influence of your sport
> (racing) on our sport (cruising).
And many crusiers who do, especially, as noted by ther posters, ball-
bearing blocks, self-tailing winches, improved roller furling systems,
modern low-stretch synthetic lines that replace dangerous wire-rope
halyards, hydraulic systems, etc.
If cruisers do not want to accept the "influences" of racing sailors on
"their" sport, they are free to support only those manufacturers and
vendors who do not utilize these influences. Apparently your views are
not shared by the majority of your bretheren, as manufacturers who do
incorporate modern, race-experience-based refinements to their products
seem to be quite successful.
Joe Ozelis
Sailboat Sales Co.
Performance Yacht Sales
www.sailboatsalesco.com
John Wilson
I've snipped quite a lot ......
But:
>many of the Fastnet "survivors" believed it was crew (in)experience,
>rather than boat design, that led to unfortunate occurences
I was skippering a Rival 34 in the English Channel during the Fastnet
storm. We were safely tucked away in Poole during the worst of it.
As the storm abated we headed west, and responded to red flares coming
from Portland Race (nasty tide rips off a headland, for those who
don't know the area).
We radioed Brixham Coastguard to keep them informed, and soon found
and towed in a Fastnet "racer", with intact rig, but broken-down
engine. The only thing stopping that boat from sailing the last few
miles into Weymouth or Portland was crew inexperience and general
exhaustion.
This was only a few months after I had been in a similar survival
storm, off Iceland. We had a much stronger crew, and despite quite
major damage and injuries sustained during an inversion and three more
knockdowns, sailed the boat home.
Crew strength is THE critical factor - but it's determination and
experience that matter more than physical strength. Most boats -
even light racers - will take an unbelievable hammering and still
survive. I see nothing wrong with taking modern light fast IMS
designs offshore - though your storm strategy may be very different to
a cruising boat's.
When I go off for a 600 mile race next week though, it will be on a
heavy 42-footer. At my age I'd rather not sit on the rail that long!
Despite my initial comments about crew experience being critical, I do
seem to remember that the enquiry found that some beamy designs were
inherently excessively stable upside down, though all eventually came
up again - unlike some recent Southern Ocean experiences. I've stood
on the headlining inside an inverted yacht, and swum alongside on the
end of my lifeline looking at a keel in the air. It's not nice. I
want a boat with a good stability curve. And yes - many IMS designs
have that.
John Wilson
Jim Manzari
John Wilson wrote:
>
<many excellent comments snipped>
> Crew strength is THE critical factor - but it's determination and
> experience that matter more than physical strength. Most boats -
> even light racers - will take an unbelievable hammering and still
> survive. I see nothing wrong with taking modern light fast IMS
> designs offshore - though your storm strategy may be very different to
> a cruising boat's.
I concur 100% regarding crew strength. Hence, the need for a boat
that will take good care of its crew in heavy going. IMO, it will
take a pretty strong crew to handle the modern racer/cruiser in heavy
weather. As you point out, the storm strategy will be different (more
work for the crew perhaps?) in light fast boats.
> Despite my initial comments about crew experience being critical, I do
> seem to remember that the enquiry found that some beamy designs were
> inherently excessively stable upside down, though all eventually came
> up again - unlike some recent Southern Ocean experiences. I've stood
> on the headlining inside an inverted yacht, and swum alongside on the
> end of my lifeline looking at a keel in the air. It's not nice. I
> want a boat with a good stability curve. And yes - many IMS designs
> have that.
It would be interesting to see the "average" or "median" angle of
vanishing stability and the ratio of areas under the positive and
negative stability curve for a group of comtemporary IMS designs (of
the same general length or size) compared to similar 1979 Fastnet
designs. I'd be willing to bet the numbers haven't changed much in
the intervening 19 years.
Garry Elmer
Jim Manzari
Joe Ozelis wrote:
>
> Very impressive - begin your reply by nit-picking a typo. Very mature.
It was a cheap shot! Please accept my apologies.
> ???? Now we know you really don't know what you are talking about
> as far as race boats are concerned.
Also true! But then this is the r.b.cruising newsgroup? I'm at home
here. Rightly or wrongly, I think of you as the guest here.
Furthermore, the other side of the coin could be that you don't know
anything about cruising. I wouldn't dream of questioning your (no
doubt considerable) ability to race in the r.b.racing forum.
> < irrelevant reference to sensational Economist article snipped>
Whether you or your industry likes it or not, the perception may be
more important than the reality regarding the seaworthiness of (some)
racing-influenced designs. One way or another your industry will
(sooner or later) have to deal with this (possibly erroneous)
perception. The Economist article is just the tip of the iceberg. I
could cite numerous similar magazine articles published over the past
year here in Europe in French, German, and British sources. As I only
see Cruising World (who has yet to say anything negative about a boat
in their entire history, as far as I can tell) I can't judge what the
situation is regarding this matter in the US.
> > I am sure you would never
> > recommend your Mumms for long-term world-wide offshore cruising.
>
> No - but for reasons other than safety.
All you need to do is backup your statements on this to convince me.
Show us the numbers and graphs and I will be singing praises about
your boats.
> ...I would never bas a reccomendation solely on a one-dimensional
> arbitrary formula that has not achieved general acceptance among the
> indsutry.
Actually, if you would look back through this thread you will see that
I have never advocating the use of a *isolated*, *singleton*, or
*singular* formula for anything. What I have said is: taking six (6)
ratios and factors (disp-lwl, bal-disp, sa-disp, Vmax, capsize-risk,
comfort-factor) *ALL TOGETHER* will provide a "short-list" of
potential candidates for long-term offshore cruising by a short-handed
crew.
For example, here are the 6 numbers for some of your Island Packet
product line...
Model disp-lwl bal-disp sa-disp Vmax cap-risk comfort
------------------- -------- -------- ------- ---- -------- -------
ISLAND PACKET 37 277.23 0.44 15.28 7.85 1.78 30.51
ISLAND PACKET 40 258.97 0.44 14.63 8.05 1.76 31.98
ISLAND PACKET 350 283.97 0.47 18.27 8.13 1.84 28.37
ISLAND PACKET 32 169.32 0.46 19.02 8.72 1.89 23.04
ISLAND PACKET 320 306.19 0.44 15.63 7.44 1.90 27.38
ISLAND PACKET 44 242.37 0.45 15.95 8.60 1.68 34.90
ISLAND PACKET 45 238.51 0.44 18.91 9.17 1.68 34.77
If I were looking for a "proper" long-term ocean cruising boat, I
would certainly want to "kick the tires" on these boats. With the
possible exception of the 32' model, which appears to be aimed at the
inshore, light-air market (disp-lwl rather low at 169, but good for
its intended purpose), any one of these boats appears, IMO, to be safe
(cap-risk well below 2, more than adequately ballasted at 0.4+), easy
for a short-handed crew to handle (sa-disp = 14-18), comfortable (at
or very close to the low to middle 30s), and capable of a good turn of
speed. All of these boats, as far as I know, have a long keel,
protected prop shaft, and fully supported rudder. These boats
epitomize the "middle-of-the-road" ideal that I have been advocating.
All, I would guess, can heave-to properly in Force 6 to Force 9
weather.
What, pray tell, could you find wrong with this list or the numbers
presented? Also, where do I send my bill for all this free
advertising I've done for you :-)?
> ...You might also find it surprising that many modern IMS designs are
> exceedingly stable (high LPS) and have high stablity curve ratios.
Again, backup your assertion with some data!
> ...performed in any meaningful way. The sailing industry is not, as
> a rule, blessed with high profit margins and excessive amounts of
> liquid (no pun intended) capital.
How come the private aviation industry can supply loads of data to
potential customers? Have you tried to purchase an aircraft recently?
The dealers will give you all sorts of technical information without
even asking. The aviation trade press is actually critical of some
designs.
Here in Europe, a French and a German boating magazine use an
interesting technique to review boats. They actually live on them for
the time it takes to sail overnight more than 100 nautical miles in
sometimes rough weather. Some really good reviews come out of this
(the beds are unusable, sheet leads are wrong, the galley is full of
sharp corners, there are not enough handholds, the head door is not
strong enough, the engine is underpowered for a boat this size, etc,
etc).
Nothing like the stuff that Cruising World publishes as part of their
"Best of 19xx" series. It is interesting to note in one recent "Best
of 19xx" the only real cruising sailor, Tom Neal, who has lived aboard
and cruised for 18 years, was overridden when he argued that a serious
risk existed due to the engine of one boat being buried in the
furniture. He argued in the event of engine failure or fire it might
be too difficult to get at quickly. THE RACERS ON THE PANEL DIDN'T
THINK THIS WAS A PROBLEM!! What could they have been thinking?
> Interstingly, much of the research on such topics that has been performed
> to date was under the auspices of Mr. Kirkman, the IMS Technical Committee,
> the ORC, local PHRF racing organizations, and the US Sailing Asociation -
> all racing organizations !
You forgot to mention that Karl Kirkman (also Fishmeal's favorite NA)
wrote parts of chapters titled "Avoiding Capsize, Research Work" and
"Avoiding Capsize, Practical Measures" in "Desirable and Undesirable
Characteristics of Offshore Yachts" by the Technical Committee of the
Cruising Club of America.
> > between, say Falmouth and Gibraltar or the Chesapeake and Bermuda, in
> > these same conditions do not have the luxury of "retiring" from the
> > cruise.
>
> But they do have the luxury of altering course or heaving-to in order to
> ameliorate the conditions on board - while the racer is constrained by the
> race course to proceed on a perhaps more unfavorable point of sail. Unless,
> of course, the cruiser finds himself having to beat off a leeward shore,
> in which case he will envy the racer's superlative VMG and pointing ability.
Superlative VMG and pointing ability will be greatly appreciated
---PROVIDED--- it does not wear down the short-handed crew. This
seems to be the sticking point in this debate: those who race for
limited periods of time with strong crews can afford to take risks
that no cruiser would contemplate. If the last 5% of performance
comes at the price of exhaustion, it simply is not worth the risk. If
easying off 10-degrees or going 0.5 knot slower means the crew can
eat, sleep, and function normally, most of the psychological pressure
is relieved. Too many crews call for assistance simply because they
are cold, wet, hungry, and frightened. Morale is a key ingredient to
survival in extreme conditions. There are far too many stories of
crews who have abandoned their boat only to have the boat continue
floating for days or weeks. Oft-times these crews have no injuries
and have months of food and water still aboard, and for whom rescue
comes 20-30 hours after the crisis has passed.
> I see nothing threatening or rude in my asking you to support your baseless
> allegations disparging the safety of a product.
Backup your claims and I will sing the praise of your products.
> > Why
> > are you so sensitive to open discussion of anything negative regarding
> > racing boats in the context of their application to cruising?
> As long as the discussion is rooted in fact and experience, not hearsay,
> the blind application of a not-universally-accepted first-order metric,
> or non-peer reviewed data and analysis, I'm sure we have no problem with
> it.
Let me get this right. In the rec.boats.cruising newsgroup I must
never question any claim made by people who CLEARLY have no expertise
in the chartered subject of the newsgroup. Furthermore, I must not
notice remarks like "bus with flat tires, slug, crab crusher, etc".
Strange concept that!! Unusual sense of fairness or sportsmanship
some of you racing fellows have!!
> You might find it interesting to note that, in agreement with what you
> have been told by Mssrs. Kamen and Schell, the work of Mr. Marchaj is
> not part of any foundation of naval architecture studies nor widely
> accepted or utilized by those in the profession. My source for this is two
> close friends of mine, both graduates of the Unversity of Michigan's
> Naval Architecture degree program, along with their classmates Bruce
> Nelson, John Reichel, and Bill Tripp.
This issue I really don't understand. I would really like to
understand this mindless prejudice by the same small group of people
in this newsgroup against this man. You state that his work is not
used in ONE university in the world!! On that basis almost every
professor in the world could be de-barred. You make a blanket
statement that implies ALL naval architects don't read or agree with
his work. Your statement is based on what real evidence of
incompetency in this man's work.
What is it that Marchaj has done to touch such a sensitive nerve in
fellows like you? Is this just "If it isn't American, it can't be any
good" parochialism? Is it a fear that if too many people read his
book on seaworthiness, they just might start asking embarrassing
questions of your industry? Is it just plain character-assassination
for some perverse pleasure?
By the way, whenever one of your favorite naval architects writes a
360 page book on the subject of seaworthiness, I will read it as
critically as I have read all of Marchaj's books. Please point me to
a book similar to Marchaj's on this same subject. I'd love to read
it.
Just for the record, for those who don't already know...Tony Marchaj
was a professor and research fellow in the Department of Aeronautics
and Astronautics at Southhampton University. He is now an independent
aerodynamics consultant. He was a national Finn champion in his
youth. His technical paper on "Design for Extreme Conditions" was
awarded the coveted Silver Metal by the Royal Institute of Naval
Architects. He has been involved in many different research projects
ranging from 12-meter rig design to third world fishing fleets. He
wrote, among others, "Sailing Performance: Theory and Practice" and
"Seaworthiness, The Forgotten Factor". His experience with tank and
wind tunnel testing plus his practical sailing experience makes him
well qualified to write on the subject of seaworthiness.
> I am well aware of Mr. Wallace's contributions to the Yacht-L mailing
> list, and he also lives in my neck of the woods. I've heard his personal
> account of the events, I do not need Mr. Rousmaniere's opinions and
> narrative inclusions.
Actually, if you would read the book, Rousmaniere took Wallace's
quotes from promotional material produced by the builder of the J-30.
> ....Nor do you make mention of the fact that a higher percentage of
> the Admiral's Cup yachts (representing to most race-oriented,
> stripped out designs) finished than the Fastnet fleet as a whole
As I understand the book, most (all) of the big boats were already
back, or nearly back, in the Channel when the worst of the storm hit.
It was the small (slower) boats still out in the Western Approaches,
that took a hammering. Hence, the concern thereafter for small racing
designs and now the offspring of these small racing designs, the
cruising/racer or so-called "performance cruiser".
> nor that the subesequent inquiry did not find a causal relationship
> between boat design and degree of casualties.
Another strange idea from you. As a result of the Fastnet Disaster
the subject of this thread "Capsize Screening Formula" was introduced.
> > John Rousmaniere is the editor of "Desirable and Undesirable
> > Characteristics of Offshore Yachts"
> and has also developed a cottage industry by preaching of the
> "unseaworthiness" of modern yachts, equipment, and techniques, while
> offering no evidence to support his claim. If your only experience with
> modern racing yachts in diffcult conditions is that provide by Mr.
> Rousamniere, you have a limited and subjective perspective, indeed.
>
Hummm...no evidence to support his (Rousmaniere's) claims. Boy, for
someone who has yet to offer any evidence for anything, that is quit a
statement!
The truth is he was only the *editor* of the book under the auspices
of the Technical Committee of the Cruising Club of America. The
actual authors were (in no special order):
Karl Kirkman - Capsize, Steering Control
Olin J. Stephens II - Trends in Yacht design, stability
Richard C. McCurdy - Capsize, yacht construction
Daniel D. Strohmeirer - The deck
William Lapworth - The cockpit
Lynn A. Williams - The cabin
Thomas R. Young - Ventilation
Roderick Stephens, Jr. - The sail plan, spars, standing rigging
Mitch Gibbons - Running rigging, sails for crusing, power
Clayton Ewing - Ground tackle
Stanley Livingston, Jr - Emergency equipment
George Griffith - Power plant
Designs presented by:
Ted Hood
Bill Lapworth
McCurdy & Rhodes
Bill Shaw
Sparkman & Stephens
BTW, did you see Fishmeal, Schell, or yourself anywhere in this
list of experts.
> And many crusiers who do, especially, as noted by ther posters, ball-
> bearing blocks, self-tailing winches, improved roller furling systems,
> modern low-stretch synthetic lines that replace dangerous wire-rope
> halyards, hydraulic systems, etc.
Please tell me when a circumnavigation *depended* on ball-bearing
blocks, self-tailing winches, or any of the other things you mention.
It is clear by your statement above that you haven't a clue about what
it actually takes to sail around the world.
I don't know how old you are, but thousands of boats have
circumnavigated without any of these items. In fact, some may have
had an easier time, simply because they were not burdened with high
tech, high failure items.
Slocum, nearly a hundred years ago, on the voyage lasting 72 days
between Juan Ferdandez Island and Samoa went without touching the
wheel for one whole month. Without roller bearings, self-tailing
winches, GPS, elliptical rudder, fin keel, open transoms,
roller-furling, etc, etc.
"I was en rapport now with my surroundings...", said he. Something, I
doubt, some racers on this newsgroup will ever be.
BTW, in my experience, some of the modern low-stretch synthetic lines
are wonderful, except for one thing: some are so prone to chaff or
abrasion damage that they last only a few months at sea.
I note you say "improved" roller furling. Could you please point out
who makes the so-called "improved" gear.
Another strange idea from you: Furling head sails as an offshoot of
racing. When was the last time you saw furling head sails on the
"serious" racer?
> If cruisers do not want to accept the "influences" of racing sailors on
> "their" sport, they are free to support only those manufacturers and
> vendors who do not utilize these influences. Apparently your views are
> not shared by the majority of your bretheren, as manufacturers who do
> incorporate modern, race-experience-based refinements to their products
> seem to be quite successful.
Once again, backup your statements with something we can check. Some
production statistics, like book to bill ratio, by builder would be
interesting.
Jim Manzari
John Wilson
On Sat, 28 Mar 1998 11:08:20 +0100, Jim Manzari <man...@bluewin.ch>
wrote:
( some snipped )
>It would be interesting to see the "average" or "median" angle of
>vanishing stability and the ratio of areas under the positive and
>negative stability curve for a group of comtemporary IMS designs (of
>the same general length or size) compared to similar 1979 Fastnet
>designs. I'd be willing to bet the numbers haven't changed much in
>the intervening 19 years.
>
I agree - it probably would not be that much different - but quite a
small change can have significant effects. Remember that in the 1979
Fastnet no boat that I know of stayed permanently inverted, though
some - the wider flatter ones - stayed the wrong way up much longer
than others. It's the length of time spent inverted that is the
danger.
The one conclusion from the Fastnet 79 enquiry that I remember was
that all the Contessa 32's - a boat I've sailed quite a lot - an
'old-fashioned' longish-keel narrow design, came through unscathed.
The beamier 'modern' OOD34s from the same manufacturer were singled
out for criticism for poor ultimate stability. They were beamy boats
without the very deep bulb-at-the-bottom keel of most current IMS
racers. I think most IMS racers would have better stability figures
than the OOD34, and would right faster.
Don't get me wrong - I don't much like IMS designs in general. I just
don't think anyone should bad-mouth them for seaworthiness. Most of
the ones I've been aboard are very well built, and are clearly
perfectly seaworthy - although uncomfortable !
John Wilson
kpk...@acpub.duke.edu
Boy, if this was a game show Jim Manzari would have gotten the buzzer
long ago. In all fairness, some his points in an earlier post were quite
right.
Jim Manzari wrote:
> ... Rightly or wrongly, I think of you as the guest here.
Are you the arbiter of "Who Belongs In A Public Newsgroup?" Your basic
problem is that you take yourself WAY too seriously.
> Furthermore, the other side of the coin could be that you don't know
> anything about cruising.
Once again, why should anyone have to submit their credentials to you? A
willingness to assume the other guy doesn't know what he's talking about
is the hallmark of a truly poor intellect.
> Whether you or your industry likes it or not, the perception may be
> more important than the reality regarding the seaworthiness of (some)
> racing-influenced designs.
Have you been reading MacLuhan? Perception is NEVER more important than
reality.
> ... Cruising World (who has yet to say anything negative about a boat
> in their entire history, as far as I can tell)
Yup- I agree with you here. But then, what do you expect? They pretty
much have to butter their bread to stay in business.
> Actually, if you would look back through this thread you will see that
> I have never advocating the use of a *isolated*, *singleton*, or
> *singular* formula for anything. What I have said is: taking six (6)
> ratios and factors (disp-lwl, bal-disp, sa-disp, Vmax, capsize-risk,
> comfort-factor) *ALL TOGETHER* will provide a "short-list" of
> potential candidates for long-term offshore cruising by a short-handed
> crew.
This is relatively sensible- but you need to look at a lot more than
numbers. Hull and rig type within a scalar range make a huge difference
to the suitablity of a given boat for a given use.
> How come the private aviation industry can supply loads of data to
> potential customers? Have you tried to purchase an aircraft recently?
> The dealers will give you all sorts of technical information without
> even asking. The aviation trade press is actually critical of some
> designs.
Engineering compaies vary widely here- some hand out sales BS, some give
hard specs, some quote specs that their equipment will not deliver. I
firmly believe in the old adage "Let the buyer beware," particularly
with boats.
> Nothing like the stuff that Cruising World publishes as part of their
> "Best of 19xx" series. It is interesting to note in one recent "Best
> of 19xx" the only real cruising sailor, Tom Neal, who has lived aboard
> and cruised for 18 years, was overridden when he argued that a serious
> risk existed due to the engine of one boat being buried in the
> furniture. He argued in the event of engine failure or fire it might
> be too difficult to get at quickly. THE RACERS ON THE PANEL DIDN'T
> THINK THIS WAS A PROBLEM!! What could they have been thinking?
The only person in that group whom I would categorize as a "racer" is
Bill Lee. However, engine access is certainly a much-overlooked point.
(long snip)
> Please tell me when a circumnavigation *depended* on ball-bearing
> blocks, self-tailing winches, or any of the other things you mention.
> It is clear by your statement above that you haven't a clue about what
> it actually takes to sail around the world.
Perhaps a circumnavigation might not *depend* on reliable, easy-to-work
gear (particularly runing rigging); but it's rather strange that you
claim a short-handed crew must be able to work a cruising boat easily,
and then disdain the value of these things. Surely rope clutches,
self-tailing winches, roller-bearing blocks, etc. all contribute to
making a boat easier to sail? And these were surely all developed
originally for racing boats?
> I don't know how old you are, but thousands of boats have
> circumnavigated without any of these items. In fact, some may have
> had an easier time, simply because they were not burdened with high
> tech, high failure items.
Yup- and anchorages weren't as crowded back then, either! You will get
no argument from me on the point "simpler is better." But people have
much higher expectations of comfort nowadays. Many of those boats were
much smaller, and so were much easier to sail simply as a matter of
scale.
>
> Slocum, nearly a hundred years ago, on the voyage lasting 72 days
> between Juan Ferdandez Island and Samoa went without touching the
> wheel for one whole month. Without roller bearings, self-tailing
> winches, GPS, elliptical rudder, fin keel, open transoms,
> roller-furling, etc, etc.
Even if these things had been available back then, Slocum couldn't have
afforded them. In fact, you might use Joshua Slocum and "Spray" as a
textbook case of an excellent sailor making passages successfully in a
totally inappropriate boat. Well, maybe not TOTALLY inappropriate- after
Slocum re-rigged her, she steered herself fairly well.
> "I was en rapport now with my surroundings...", said he. Something, I
> doubt, some racers on this newsgroup will ever be.
You obviously do not have even the tiniest clue about racing. To use the
wind with all it's variation, to read the tide or currents quickly and
accurately, and to feel the boat's smallest urges are the foundation of
any skill in racing. Look up "rapport" in the dictionary...
> BTW, in my experience, some of the modern low-stretch synthetic lines
> are wonderful, except for one thing: some are so prone to chaff or
> abrasion damage that they last only a few months at sea.
Uh huh. And manila would last how long??
>
> I note you say "improved" roller furling. Could you please point out
> who makes the so-called "improved" gear.
Schafer and Harken, to name only two. Roller furlers are immensely
stronger, easier to work, and more reliable than they were ten year ago.
>
> Another strange idea from you: Furling head sails as an offshoot of
> racing. When was the last time you saw furling head sails on the
> "serious" racer?
A whole lot- like the entire singlehanded and doublehanded fleets.
It appears Jim Mazari is beginning to show somewhat of a human side, and
has made a few good points. But he still jumps off the deep end with
absolutely no facts entirely too often.
Fresh Breezes- Doug King
t.r.mcloughlin
Jim Manzari wrote:
>
> Joe Ozelis wrote:
> > You might find it interesting to note that, in agreement with what you
> > have been told by Mssrs. Kamen and Schell, the work of Mr. Marchaj is
> > not part of any foundation of naval architecture studies nor widely
> > accepted or utilized by those in the profession.
> This issue I really don't understand. I would really like to
> understand this mindless prejudice by the same small group of people
> in this newsgroup against this man. You state that his work is not
> used in ONE university in the world!! On that basis almost every
> professor in the world could be de-barred. You make a blanket
> statement that implies ALL naval architects don't read or agree with
> his work.
I'd like to ask permission to include the prior exchange in
one of my upcoming peer-reviewed monographs (working title:
Reading or Comprehension: Effect Dynamic Roll Loading
Induced Selective Transocular Distinction on Semiomapping. )
There's tons of useful info being pressed out of this
conversation, but do us all a favor and stop diving
into boundary condition foxholes. . .
Remember "widely" does not mean the same as "ALL". And
"not part of any foundation" does not mean the same thing as
"his work is not used".
ObCruising: I won a trophy once, too.
trm
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
<snip>
>It would be interesting to see the "average" or "median" angle of
>vanishing stability and the ratio of areas under the positive and
>negative stability curve for a group of comtemporary IMS designs (of
>the same general length or size) compared to similar 1979 Fastnet
>designs. I'd be willing to bet the numbers haven't changed much in
>the intervening 19 years.
Well, I don't have the sampling data you are looking for, but I know
enough about the IOR and IMS rules to know what the outcome would be.
The IMS rule does not, in any way, offer unfair penalties for
increased ballast. There are a number of IMS boats with ballast/disp
ratios of around 45% (and the CG of that ballast is typically 6 feet
below the waterline!). This is both more and deeper ballast
than competitive IOR boats.
In fact, some racer/cruisers are offered in both "dual-purpose" and
"IMS" configuration. I think that Swan and J-boats both do this with
the larger boats. If you compare the two configurations (and
specify the same draft), the IMS boat will have the same or *more*
ballast than the boat that was not optimized to any rule. For the
J-160 I think this amounts to a couple thousand lbs of additional lead.
Given that the designer puts more lead in the IMS design compared to
the design without an reference to a measurment rules, I don't see
how you can claim that this rule is somehow causing boats that are
prone to capsize. There *are* light boats that are designed to IMS
rules; some of these are even competitive under the rule. However,
the IMS does not encourage a particularly light design. It does
encourage relatively deep ballast and huge sail area... but no one is
forcing you to carry those big sails when you are not racing.
Sincerely,
Terry
Jim Manzari
John Wilson wrote:
>
> The one conclusion from the Fastnet 79 enquiry that I remember was
> that all the Contessa 32's - a boat I've sailed quite a lot - an
> 'old-fashioned' longish-keel narrow design, came through unscathed.
An interesting coincidence is that David Sadler, the designer of the
Contessa 32, was involved in the 1994 Pacific Storm off New Zealand,
which I mention earlier in this thread. He hove-to in his boat Kiwi
Dream, "a steel 10.8 meter sloop, 7.5 tons, in 50-60 knots of wind in
very big swell with breaking crusts". The boat survived unscathed,
but he suffer 3 broken ribs.
> The beamier 'modern' OOD34s from the same manufacturer were singled
> out for criticism for poor ultimate stability. They were beamy boats
> without the very deep bulb-at-the-bottom keel of most current IMS
> racers. I think most IMS racers would have better stability figures
> than the OOD34, and would right faster.
I'm beginning to understand the reasons for the better IMS stability.
Still wouldn't mind seeing the actual data, however. It would be
easier to make some statistical comparisons.
> Don't get me wrong - I don't much like IMS designs in general. I just
> don't think anyone should bad-mouth them for seaworthiness. Most of
> the ones I've been aboard are very well built, and are clearly
> perfectly seaworthy - although uncomfortable !
I've never criticized a specific IMS design, as I have no interest in
racing except as it influences cruising designs. But I do think it
strange that the stability data for all IMS designs is restricted to
only those who will pay for it. Why this funny arrangement on basic
safety data?
Actually, my biggest complaints are reserved for the off shoots of
some of the current racing designs. Simply calling a racing boat a
"performance" cruiser does not magically endow it with increased
sea-worthiness or capable of long-term offshore cruising, IMO.
I wish one or more of the racing enthusiast on this ng would explain
the benefits to a cruiser of the following:
Spade rudder
Deep, narrow fin keel
Vertical foreward sections
Flat bottom
Wide, shallow aft sections
Low freeboard
Unbalanced or asymmetric heeled waterlines
Weak structure in the bow where anchor loads are concentrated
I'm afraid to ask about open transoms :-).
The context of your answer should be a 4-6 year circumnavigation by a
husband and wife with excursions out of the tropical regions to visit
Alaska, Chile, New Zealand, etc.
Regards,
Jim Manzari
Jim Manzari
Terry Schell wrote:
> Well, I don't have the sampling data you are looking for, but I know
> enough about the IOR and IMS rules to know what the outcome would be.
> The IMS rule does not, in any way, offer unfair penalties for
> increased ballast. There are a number of IMS boats with ballast/disp
> ratios of around 45% (and the CG of that ballast is typically 6 feet
> below the waterline!). This is both more and deeper ballast
> than competitive IOR boats.
Backup your statement. And what do you mean exactly by "a number of
IMS boats"? Does this mean 50%, 90%, or what?
> In fact, some racer/cruisers are offered in both "dual-purpose" and
> "IMS" configuration. I think that Swan and J-boats both do this with
> the larger boats. If you compare the two configurations (and
> specify the same draft), the IMS boat will have the same or *more*
> ballast than the boat that was not optimized to any rule. For the
> J-160 I think this amounts to a couple thousand lbs of additional lead.
Just curious, is this "dual-purpose" part of the IMS 1% allowance for
cruise-capable designs?
> ...I don't see how you can claim that this rule is somehow causing
> boats that are prone to capsize.
I don't think I've never explicitly claimed that any boat is "prone"
to capsize due to some racing rule. Those are your words, not mine.
What I have said is: when taken ALL TOGETHER the six (6) ratios and
factors (disp-lwl, bal-disp, sa-disp, Vmax, capsize-risk,
comfort-factor) form a pretty good *short-list* of candidate boats for
safe, comfortable, and fast long-term offshore cruising.
Terry Schell
>IMS boats"? Does this mean 50%, 90%, or what?
I don't have a representative sample of boats... and I told you that
before I mentioned this... so I cannot give you the information you
want. If you would take the time, you can get the specifications of
many of the current IMS boats off the web and check for yourself.
>> In fact, some racer/cruisers are offered in both "dual-purpose" and
>> "IMS" configuration. I think that Swan and J-boats both do this with
>> the larger boats. If you compare the two configurations (and
>> specify the same draft), the IMS boat will have the same or *more*
>> ballast than the boat that was not optimized to any rule. For the
>> J-160 I think this amounts to a couple thousand lbs of additional lead.
>Just curious, is this "dual-purpose" part of the IMS 1% allowance for
>cruise-capable designs?
No. Dual-purpose is for PHRF or cruising (or the round the
world rally, which is what hull #1 did). The IMS version does get the
1% allowance. For someone who talks so much about how racing rules
have polluted yacht design, you don't seem to know much about the
rules.
<snip>
>What I have said is: when taken ALL TOGETHER the six (6) ratios and
>factors (disp-lwl, bal-disp, sa-disp, Vmax, capsize-risk,
>comfort-factor) form a pretty good *short-list* of candidate boats for
>safe, comfortable, and fast long-term offshore cruising.
Because it can exclude some boats that make perfectly good cruisers
for some people. For instance, I would love a boat with a SA/D of 25.
According to your criteria that would indicate a boat that is
dangerous and uncomfortable, since it is way above the median.
However, no one forces you to carry more sail than is safe just because
you have the stick that can handle it. There isn't really any danger in
having the extra ability to carry sail when conditions and crew allow,
even if it means that on a single handed passage you leave a reef in the
whole time. For the kind of cruising I like to do, the median SA/D
boat would be a very bad choice.
In short, your method is a "pattern matcher" in the statistical sense.
It does not help you find the ideal offshore crusing boat... it helps
you rate boats relative to your predetermined ideal. It cannot
justify the original prejudices that led to you determining an ideal.
If someone questions those prejudices, you cannot get out of it by
including 6 indicators. I think there are good reasons to question
your prejudices, particularly when applied to all types of cruising.
Sincerely,
Terry
John Wilson
>Superlative VMG and pointing ability will be greatly appreciated
>---PROVIDED--- it does not wear down the short-handed crew. This
>seems to be the sticking point in this debate: those who race for
>limited periods of time with strong crews can afford to take risks
>that no cruiser would contemplate. If the last 5% of performance
>comes at the price of exhaustion, it simply is not worth the risk.
Two years ago I was offshore racing on a light fast Danish 37-footer (
definitely a racer ) that was close-reaching along flat-out under full
sail, going almost airborne at times, digging in the bow to take water
grren at times, and showing 10-11 knots on the dial (though actually
making a bit less!). After two days of this I was the only one not
sick, and the crew of six was down to about two and a half functioning
members.
OK - you say - this proves 'racers' aren't suitable as cruisers. But
does it. We reefed it down, put up a smaller jib, and we were still
showing 9 knots, but now we were dry and with a much easier motion.
Even slowed down the light boat was outperforming heavier boats of the
same length.
And though I race quite a lot, I cruise too ( defining cruising as
sailing for pleasure, interest and transportation to places you can't
get to otherwise ). I have not and probably never will circumnavigae
under sail, but I've logged a lot of miles, including blue-water
passages not racing. I see no reason why someone who coastal cruises
shouldn't be defined as 'cruising'. If we restrict this NG to
long-distance liveaboards with internet access there would be very few
correspondents!
John Wilson
John Wilson
>An interesting coincidence is that David Sadler, the designer of the
>Contessa 32, was involved in the 1994 Pacific Storm off New Zealand,
>which I mention earlier in this thread. He hove-to in his boat Kiwi
>Dream, "a steel 10.8 meter sloop, 7.5 tons, in 50-60 knots of wind in
>very big swell with breaking crusts". The boat survived unscathed,
>but he suffer 3 broken ribs.
I see he's reverting to his early training as
an army tank designer : )
( it's actually true ! )
And I like his boats ........
>Actually, my biggest complaints are reserved for the off shoots of
>some of the current racing designs. Simply calling a racing boat a
>"performance" cruiser does not magically endow it with increased
>sea-worthiness or capable of long-term offshore cruising, IMO.
>
>I wish one or more of the racing enthusiast on this ng would explain
>the benefits to a cruiser of the following:
>
>Spade rudder
>Deep, narrow fin keel
>Vertical foreward sections
>Flat bottom
>Wide, shallow aft sections
>Low freeboard
>Unbalanced or asymmetric heeled waterlines
>Weak structure in the bow where anchor loads are concentrated
>
>I'm afraid to ask about open transoms :-).
>
>The context of your answer should be a 4-6 year circumnavigation by a
>husband and wife with excursions out of the tropical regions to visit
>Alaska, Chile, New Zealand, etc.
>
>Regards,
>Jim Manzari
>
Can't see why anyone would want any of these features given the
long-distance and short-handed nature of the cruise. Except maybe the
open transom !!!!! Given THIS brief I'd go either very expensively
big cruising ultralight ( Sundeer style ) or a lot cheaper heavyish
displacement traditional cruiser - maybe Rival 38, Bowman 40 or 45, or
similar, or a steel hulled equivalent.
This is not to say that you can't coastal cruise safely and quickly in
a racing-derived boat, as long as it's strongly built. And coastal
cruising is cruising too, in my book.
John Wilson.
macnaughton.com
I have a feeling I should have been following this thread. We do have some
expertise in these areas. However, I just want to make the point that many
of the boating magazines cannot survive financially with their current
structure and the way advertising is handled if they criticize their
advertisers boats. That doesn't make it right. Also while an amateur may be
able to get away with saying "The Macho 35 is a poorly built boat." The
professional will be sued immediately and asked to face a highly paid legal
team in court.
I would also point out that roller furling gear was in use before the turn
of the century and people have been talking about how improved the latest
models are all my life. They still don't seem very great to me.
Tom MacNaughton
http://www.macnaughtongroup.com
macnaughton.com
As I have said I should have been following this thread. I am surprised that
anyone is criticizing Mr. Marchaj and would love to know on what basis. We
use his book "Seaworthiness" and his "Aero-Hydrodynamics of Sailing" in our
Yacht Design School and find them to be very highly regarded by the naval
architects we know. Mr. Marchaj's work has always been consulted by our
design firm and others that we know of. I find him very highly regarded in
the industry.
Tom MacNaughton
Naval Architect / Business Manager
http://www.macnaughtongroup.com
Robby Robinson
macnaughton.com wrote:
> I would also point out that roller furling gear was in use before the turn
> of the century and people have been talking about how improved the latest
> models are all my life. They still don't seem very great to me.
Tom what is it you don't like about roller furling (furling -- not
reefing)? My Harken system has been 100% trouble free on RS since it
was installed in 94 (to replace a previously trouble free Stearns
system). We use it every summer all summer over a lot of miles. In my
experience it is a rare cruising boat that does not have roller furling.
Most full time cruisers (e.g. more than 2 week vacation) are retired
couples where trips to the foredeck in the middle of the night are a
safety issue.
The real test of these systems has been the singlehanded races around
the world. To the best of my knowledge all the racers use them. I
believe the top choices are the Pro-furl, Harken and maybe Reichman
(sp-German).
--
Regards Robby [rob...@pacbell.net]
S/V Rolling Stone http://www.selfsteer.com/rolling-stone.jpg (currently
in Maine)
Visit home of MONITOR windvanes: http://www.selfsteer.com/
Paul Kamen
Jim Manzari <man...@bluewin.ch> writes:
>...I wish one or more of the racing enthusiast on this ng
>would explain the benefits to a cruiser of the following:
>Spade rudder
Speed under sail, especially in light air, reducing dependence on the
engine.
Maneuverability under sail, allowing sailing in and out of small
anchorages and berths.
>Deep, narrow fin keel
Stability and capsize resistance.
Speed under sail.
Maneuverability under sail.
The deep draft becomes a liability at most cruising destinations.
A well engineered retractable deep fin keel would be much better.
>Vertical foreward sections
(If you mean "U-shaped" sections, this is a consequence of light
displacement and maximizing waterline length.)
Light displacement contributes to speed and maneuverability under sail.
Light displacement reduces weight of gear, ground tackle, and size of
rig for easy handling by a short crew.
Allows a short crew to handle a larger boat for better seakeeping and
more comfortable motions.
Light displacement allows for positive flotation for a considerable
safety advantage.
(Subjective: light displacement boats are more fun to sail.)
>Flat bottom
Also a consequence of light displacement, along with waterline and
waterplane considerations.
(Downside: increased slamming under some conditions.)
>Wide, shallow aft sections
Improves downwind steering and control.
Contributes to downwind speed.
>Low freeboard
Another consequence of light weight.
Improves windward performance.
(downside: reduces cabin volume, sometimes increases water on deck.)
>Unbalanced or asymmetric heeled waterlines
A consequence of the wide shallow aft sections.
>Weak structure in the bow where anchor loads are concentrated
No advantage, only found on cheap boats.
>I'm afraid to ask about open transoms :-).
Fast cockpit draining, easy boarding, less weight, better looking ;-)
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Anders Svensson
Paul Kamen <fish...@netcom.com> wrote
> Jim Manzari <man...@bluewin.ch> writes:
>
> >...I wish one or more of the racing enthusiast on this ng
> >would explain the benefits to a cruiser of the following:
>
>
> >Flat bottom
>
> Also a consequence of light displacement, along with waterline and
> waterplane considerations.
>
> (Downside: increased slamming under some conditions.)
>
Another point: Sailboats usually heel when beating. If the hull is 'sharp',
say 30 degrees vee form, the slamming in the forward section will be
tremendous. A U formed bow section can therefore be designed to actually
be sharper when heeled than a deep built hull.
Then, I think it should be said that there are boats that look, feel and
sail well, even if they are very different in kind and type.
Where I live, we like the Nordic Folkboat - designed in the 40's and very
traditional. Compared to a J24 or a maybe a Merit 22 (a 'better' J24 if I
have understood correctly) it is a very different animal - yet they are
both 'nice boats' that sail well - or very well.
Sailors usually like both these boats because of the feel-good factor that
they both have. But if raced togeter, the J24 will win every time,
ofcourse.
Forced to choose between these two, I would have a hard time
Anders
Jim Manzari
John Wilson wrote:
>
> Two years ago I was offshore racing on a light fast Danish 37-footer (
> definitely a racer ) that was close-reaching along flat-out under full
> sail, going almost airborne at times, digging in the bow to take water
> grren at times, and showing 10-11 knots on the dial (though actually
> making a bit less!). After two days of this I was the only one not
> sick, and the crew of six was down to about two and a half functioning
> members.
Good story. I wonder what one would have done if it were just a
husband and wife for crew, thousands of miles from a safe harbor and
in much heavier weather than what you describe? I wonder if the boat
could have been stopped. Could you have hove-to? How would you feed
this crew if the trip had lasted two weeks?
> OK - you say - this proves 'racers' aren't suitable as cruisers.
I'm not sure what it proves. I think some bluewater cruising sailors
would reach the conclusion that what you describe would NOT be a "good
thing" while on a circumnavigation by a husband and wife or family.
> But does it. We reefed it down, put up a smaller jib, and we were
> still showing 9 knots, but now we were dry and with a much easier
> motion. Even slowed down the light boat was outperforming heavier
> boats of the same length.
I wonder what would have happened, in heavier weather, had the boat
fallen at 9 knots into a 30 foot hole or off the face of the 30 foot
wave. Would it have pitch-poled ass-end over tea-kettle?
Of course, this may be an acceptable risk when racing for few days
close to land and with rescue services on call a few minutes or hours
away, but I can't see the average husband and wife doing this while
circumnavigating. Two entirely different mind sets. One is to
complete the voyage at all cost and the other is to win at all cost.
> I see no reason why someone who coastal cruises shouldn't be defined
> as 'cruising'.
Nor do I. IMO, sailing in the middle of the ocean removes about 90%
of the dangers -- most dangers are found only near shore. I consider
anyone who cruises inshore to have a much more difficult problem, all
things considered. However, a thousand miles from a safe anchorage it
would be nice to have a boat that can survive any kind of heavy
weather. Inshore or offshore the boat should be able to "take care"
of the crew to avoid a crisis of exhaustion similar to what you have
described above. Crew strength and morale is a finite resource.
Notwithstanding these comments, unlike the coastal cruiser or the
racer, there is no possibility of a safe haven (a place to stop and
rest) for the offshore cruiser. To stop and rest requires a boat that
will properly heave-to in Force 6 to Force 9 conditions.
You might want to get a copy of Kim Taylor's 1994 Pacific Storm report
and read what Sadler has to say about this subject. Several of the
survivors, who survived with little injury or damage, mentioned the
need to eat and rest to insure they would have the strength needed to
handle a crisis. This would be extremely difficult, if not
impossible, to do in a boat such as you have described above, IMO.
Jim Manzari
Jim Manzari
Can anyone in this newsgroup explain what are the benefits to a
bluewater cruising yacht, and its skipper and crew, to have any or all
of the following features:
Spade rudder
Deep, narrow, thin fin keel
Vertical foreward hull sections
Flat bottom hull
Wide, shallow aft hull sections
Low freeboard
Unbalanced or asymmetrical heeled waterlines
Shallow or non-existent bilge space
Swept-back spreaders
Carbonfiber mast needing 3 or more spreaders
5 or more batten pockets in the main
Battens in the head sails
To put some scope around this question, please assume a husband and
wife crew on a circumnavigation of about 5 years duration with
excursions outside the tradewinds to regions such as New Zealand,
Alaska, Chile, Sweden, for example. Please assume 6 months supply of
fuel and food must be carried. 2 months supply of water. Please
assume a general boat length limited about 32 to 45 feet LOA.
I'll post a summary of replies, less names, for those who wish to
reply via private email.
Thanks in advance,
Jim Manzari
allen r. perrins
Help---
Trying to remove a Barient 19ST two speed Offshore
model.
I have removed the circular snap ring from the top and removed the
identificaton ring. I believe the stainless steel take-off arm for the
self-tailing feature and the whole drum should now lift off. Gentle
persuasion does not make the system budge. The drum assembly will lift
only about 1/32 of an inch. I am reasonably sure I remember that this
routine worked on a 32ST when i wanted to change the angle of the
pick-off arm. I hate like hell to saw thru the teak mounting plate.
I can't get at the nuts very easily and trying to keep the bolts from
spinning while doing so would be next to impossible. I would like to
reuse the winch in another location BUT----
Any help would be greatly appreciated
Al
Aerts
I must say this has been (so far) a very interesting Thread. Lots of valid
points have been made by a lot of experts in the field of both Cruising and
Racing. My question is am I the lone Man out here? I have a full keel
cruiser...and low and behold I race it a lot. I don't win a lot... that's
not why I race I think. I find that by entering races I can tune up my boat
to sail better and tune my skills as well. I don't know much about capsize
screens, ratios and comfort factors. I admit that I am usually the butt of
most jokes in my club's racing circle, but then again those single minded
racers don't have a crew of skimply dressed girls and the cockpit table
deployed while rounding the buoys. ( Comfort Factor?). I have won a couple
of races and usually place well in the fleet to the surprise of the "go
fasts". I can't justifiably use very much of the high tech stuff on my
boat... it's not practical. I do however gain a much better understanding of
the strong points of my boat while competing against the "sleds". I do
think that racing contributes a lot to the cruising fraternity, in so much
as gear, hull design and sail configurations are concerned. As far as using
racing designs for cruising .. I think it would be presumptuous to think
that anyone contemplating ocean passages does not have a set of parameters
regarding their vessel of choice. If someone decides to cruise in a racing
design.. I guess that's their choice. I have coastal cruised with friends in
racing boats and they have never had problems even in very bad weather. I
have come to the belief that good seamanship is the primary factor in boat
safety.
Guy Aerts - s.v.Overproof
Jim Manzari wrote in message <352248E2...@bluewin.ch>...
>John Wilson wrote:
*******************************************
>
>
Terry Schell
"Aerts" <jaa...@istar.ca> writes:
<snip>
>... I admit that I am usually the butt of
>most jokes in my club's racing circle, but then again those single minded
>racers don't have a crew of skimply dressed girls and the cockpit table
>deployed while rounding the buoys. ( Comfort Factor?).
I think you can safely assume that you are the butt of jokes only
because the others are jealous of your...um... vessel. All sailors can
get a bit green when they realize that aren't on the boat with the
"best" crew.
John Wilson
Well said!
John Wilson.
On Thu, 02 Apr 1998 17:46:31 GMT, "Aerts" <jaa...@istar.ca> wrote:
>I must say this has been (so far) a very interesting Thread. Lots of valid
>points have been made by a lot of experts in the field of both Cruising and
>Racing. My question is am I the lone Man out here? I have a full keel
>cruiser...and low and behold I race it a lot. I don't win a lot... that's
>not why I race I think. I find that by entering races I can tune up my boat
>to sail better and tune my skills as well. I don't know much about capsize
>screens, ratios and comfort factors. I admit that I am usually the butt of
>most jokes in my club's racing circle, but then again those single minded
>racers don't have a crew of skimply dressed girls and the cockpit table
John Wilson
>Good story. I wonder what one would have done if it were just a
>husband and wife for crew, thousands of miles from a safe harbor and
>in much heavier weather than what you describe? I wonder if the boat
>could have been stopped. Could you have hove-to? How would you feed
>this crew if the trip had lasted two weeks?
>
I agree - a light fractional rigged 37-footer would not be my first
choice for let us say a northern route Atlantic crossing, or any
voyage that included one of the three Capes. The boat in question
heaves to badly - it just does not want to stop.
>I'm not sure what it proves. I think some bluewater cruising sailors
>would reach the conclusion that what you describe would NOT be a "good
>thing" while on a circumnavigation by a husband and wife or family.
>
>> But does it. We reefed it down, put up a smaller jib, and we were
>> still showing 9 knots, but now we were dry and with a much easier
>> motion. Even slowed down the light boat was outperforming heavier
>> boats of the same length.
>
>I wonder what would have happened, in heavier weather, had the boat
>fallen at 9 knots into a 30 foot hole or off the face of the 30 foot
>wave. Would it have pitch-poled ass-end over tea-kettle?
>
If you'd gone downwind - probably. I've been there, pitchpoled, in
the very cold North Atlantic in May 1979, in another racing-derived
IOR design. But the boat could - just - go to windward, or at least
hold off a lee shore, in conditions that would wreck many a heavy
long-keeled boat. In fact, we got out of the situation - after three
more bad knockdowns - by getting the bows into the breakers under
storm jib alone. No heavy boat could have done this.
Please don't get me wrong. I'm not preaching that light boats are the
answer for ocean passages. I'm just saying that they shouldn't be
written off. If I had the money I'd be very tempted by a BIG
high-tech ultralight as a shorthanded - or singlehanded for that
matter - ocean cruiser. But the key is BIG. Without a lot of money
though I'd go heavyish-displacement, longish-fin-keel-and-skeg-hung
rudder etc. etc.
>IMO, sailing in the middle of the ocean removes about 90%
>of the dangers -- most dangers are found only near shore.
I know - isn't it nice!
>Crew strength and morale is a finite resource.
I agree entirely. In my opinion, the factors that control or affect
safety at sea are, in order of importance:
1. Knowledge and experience
2. Morale, mental strength or general bloody-minded refusal to give
up - call it what you like. Physical strength doesn't really factor
into this - the "fitties" are often the first to cave in.
3. Proper personal clothing/kit for the situation
4. More knowledge and experience
5. Lots of instant energy snacks
6. More morale and bloody-mindedness, etc. etc.....
7. Boat design and construction comes about here in the list. Apart
from the most dreadful errors in choice of boat for the trip, eg.
light glass boat for passage to Antactica, most boats will if properly
maintained outlast the crew in survival conditions. The illusion that
heavy boats will "protect" you is in my opinion an illusion. I
believe "Sandjefiord" - a very heavy wooden Scandinavian 70 foot
double-ender, was pitchpoled mid-Atlantic many years ago. I've seen
US Coastguard photographs of a 60' schooner being rolled. Certainly
"Tzu Hang", a classic 46 foot heavy displacement cruiser has been both
rolled and pitchpoled, on separate voyages, in the same waters (off
cape Horn). Once conditions reach a certain point, heaving to to
rest, or even running under bare poles, becomes unsafe, unless the
boat is VERY big.
Crew knowledge and experience can come in many ways. Some time ago we
had a thread about how best to learn to sail. 'Fishmeal' said learn
in as small a boat as you can - because a 14 foot boat in 20 knots
handles much like a 40 foot boat in 40 knots. I agree entirely. You
don't actually get much chance to sail 40 foot boats in 40+ knots, and
when it does happen the reflexes and instinctive skills you learn in
small boats pays off hands down.
A few months after being pitchpoled and rolled mid-Atlantic, I took
one of the same crew coastal dinghy sailing in about 25-30 knots wind,
reefed down. We had an hour's pure fun, blasting around on a series of
reaches, until I capsized. It was an old dinghy, and the buoyancy was
inflatable bags, two out of five of which broke their lashings. By
the time we'd righted it and baled enough to get sailing again the
tide had taken us a mile down-tide of the clubhouse. We sailed back,
nursing the half-filled boat through the wind-against-tide chop. When
we got back to the slipway, the crew said - "Now I know where you
learned to sail to windward in Force 10". The point is that in the
dinghy at no time were we in any danger. We had a club safety boat
around, and even if we hadn't I could have reached off under jib alone
and easily brought a swamped boat to a different club five miles
down-tide.
I'm off on a long race next week, but when I get back I'll be out on
my Laser again.
John Wilson.
Anders Svensson
John Wilson <jwi...@asiaonline.net> wrote...
> I agree entirely. In my opinion, the factors that control or affect
> safety at sea are, in order of importance:
>
> 1. Knowledge and experience
...
> 4. More knowledge and experience
...
> 7. Boat design and construction comes about here in the list. Apart
> from the most dreadful errors in choice of boat for the trip, eg.
> light glass boat for passage to Antactica, most boats will if properly
> maintained outlast the crew in survival conditions. The illusion that
> heavy boats will "protect" you is in my opinion an illusion.
I think this as a very good post on this particular issue.
The importance of knowledge and experience is clearly underrated by many.
There is (as I said in a post long ago) boats that only an idot will take
for a world cruise - but there is no boat that will guarantee the same
idiot a safe journey.
If you compare the skills of trained and knowledgeable "professionals" and
what they can achieve with the best material available (like golf, downhill
skiing or - sailing) with the average guy doing the same thing, you will
immediately understand where the real difference is.
So, when you have reached the levels of skill, knowledge and discretion
that is IMHO necessary for the happy outcome of a round the world tour in a
small boat (and all boats are small on the ocean) I think you can also be
trusted to choose the boat after your own mind. .
Anders
PrinceMyshkin
In article <6g0iob$q...@bgtnsc03.worldnet.att.net>, bar...@worldnet.att.net
says...
>
>Help---
>Trying to remove a Barient 19ST two speed Offshore
> model.
>I have removed the circular snap ring from the top and removed the
>identificaton ring. I believe the stainless steel take-off arm for the
>self-tailing feature and the whole drum should now lift off. Gentle
>persuasion does not make the system budge.
I had the same problem with one of my two 46STs. It would not come apart for
lubricating though the other one did so very easily. I suspect a burr on
something inside. Never did solve it so can't really help though I sure would
like to see a solution posted.
Anders Svensson
PrinceMyshkin <p...@pipeline.com> wrote...
This is a far shot, but...
On my Barient winches the drum is held by a small inhex bolt down in the
winch socket. Could this be the case here too? The kind I have is not ST,
BTW, but ordinary two speed. There was even a special tool delivered with
the winch, a hollow winch handle (sort of) to hold the winch drum
stationary while loosening the bolthead.
Anders
Brian Grant
PrinceMyshkin wrote:
>
> In article <6g0iob$q...@bgtnsc03.worldnet.att.net>, bar...@worldnet.att.net
> says...
> >
> >Help---
> >Trying to remove a Barient 19ST two speed Offshore
> > model.
> >I have removed the circular snap ring from the top and removed the
> >identificaton ring. I believe the stainless steel take-off arm for the
> >self-tailing feature and the whole drum should now lift off. Gentle
> >persuasion does not make the system budge.
>
> I had the same problem with one of my two 46STs. It would not come apart for
> lubricating though the other one did so very easily. I suspect a burr on
> something inside. Never did solve it so can't really help though I sure would
> like to see a solution posted.
My barients have two roller bearings beneath a bushing or spacer type of
bearing. the self tailers are connected via a spline at the top of the
shaft. They do not rotate and the spline could be frozen or the grease
on the bushing/spacer may have gotten really solid (If the drum rotates,
the bushing grease is probably OK). I would try WD40 while trying to
rock the self tailer. It won't really move but rocking it will allow
for better penetration. If it is frozen with corrosion or salt, the
WD40 should break that loose and allow you to lift the drum and tailer
off at the same time. Be careful, the bushing usually comes up with the
drum and falls out pretty quickly. If your grease is old and hard, it
may also lift out the roller bearings.
Paul Kamen
Anders Svensson <anders.-.ei...@swip.net> writes:
>...So, when you have reached the levels of skill, knowledge
>and discretion that is IMHO necessary for the happy
>outcome of a round the world tour in a small boat (and all
>boats are small on the ocean) I think you can also be
>trusted to choose the boat after your own mind. .
Right, but this should not be misinterpreted to mean that small boats are
more difficult to sail offshore than larger ones. Keep in mind that most
serious problems offshore seem to have more to do with auxilliary system
failures or other handling problems that only get more complex with
increased size. I submit that a relative beginner is far more likely to
complete a voyage successfully in a small boat than a big one - albeit
with a little less "comfort."
The current record-holder for sailing a small boat around the world is now
the manager of my yacht club. (Serge Testa, 11 ft. 10 inches length on
deck. Yes that's eleven feet ten inches.) While he's certainly a skilled
sailor, it's interesting to note that his book is relatively thin because
he really doesn't have that much of a sea story to tell. It's practically
a travellog, because the boat encountered few problems and he had time to
see the sights everywhere he went.
Anders Svensson
Paul Kamen <fish...@netcom.com> skrev i inlägg
<fishmeal...@netcom.com>...
> Anders Svensson <anders.-.ei...@swip.net> writes:
>
> >...So, when you have reached the levels of skill, knowledge
> >and discretion that is IMHO necessary for the happy
> >outcome of a round the world tour in a small boat (and all
> >boats are small on the ocean) I think you can also be
> >trusted to choose the boat after your own mind. .
>
> Right, but this should not be misinterpreted to mean that small boats are
> more difficult to sail offshore than larger ones.
The only more difficult thing may be to keep on going for as long as the
bigger boat will. The smaller boat will be slower because of its size, but
also because it will probably have a little less windward ability - given
that the boats are similar in kind.
> Keep in mind that most
> serious problems offshore seem to have more to do with auxilliary system
> failures or other handling problems that only get more complex with
> increased size. I submit that a relative beginner is far more likely to
> complete a voyage successfully in a small boat than a big one - albeit
> with a little less "comfort."
I have had the pleasure of meeting Sven Lundin. He has made the 'go small -
go cheap' to an way of life. He, too, advocates the small boat for its
simplicity. Most people would not like to go to these extremes but there
are lot of proof that many small boats are perfectly safe and adequate.
Certainly, structural loads are much less in small boats, and safety
margins for structural failure are usually greater in smaller boats - wich
may be a little counter intuitive. The subsystem reasoning is quite
correct. I have spent much more time working and servicing the engine, the
toilet and the electrical and water systems on my current boat than I have
spent on the rig or the hull.
I would prepare myself for being a bit more tossed about in a 11 foot boat
than in a 35 foot one, tho'. Thats a problem mostly on the actual voyage -
time spent in anchorages or harbours will not be much different in the
'tossing around' respect.
I spent some long summers cruising Scandinavia in a 16 foot plywood
sailboat, and I cannot remember having any less fun than I have today on 35
foot...
Anders
meuz...@mail.marc.utah.edu
fish...@netcom.com (Paul Kamen) wrote:
> Right, but this should not be misinterpreted to mean that small boats are
> more difficult to sail offshore than larger ones. Keep in mind that most
> serious problems offshore seem to have more to do with auxilliary system
> failures or other handling problems that only get more complex with
> increased size. I submit that a relative beginner is far more likely to
> complete a voyage successfully in a small boat than a big one - albeit
> with a little less "comfort."
As my co-skipper and I will be getting on in age and expect to do more
double-handed cruising, rather than with 2 or 3 additional crew members, we
eventually plan to downsize a bit from our current 43 footer to something
like a 35-38 ft pilothouse (as long as it's not a slug). In fact, we have
even admired and coveted smaller boats. However, two pieces of negative
information on offshore behavior of small boats stick into our mind and will
probably keep us from considering anything much smaller, namely:
(1) a table in the back of Rousmaniere's book on the fateful Fastnet Storm
shows (quoting from memory here, sorry for possible errors) that all boats
under 30 ft had to be abandoned, all boats between 30 and 40 ft got into
serious trouble (some abandoned), and only a few vessels over 40 ft had major
problems (none abandoned); and
(2) in Hilo we met the skipper of "Blow Me" (a beautiful Catalina-style 23
footer which he had just single-handed from the mainland in the heavy,
following tradewind seas) who complained that the trip had been one long
yawing ordeal where lying down in the center of the cabin floor was his only
chance of catnapping, let alone sleeping.
Presumably, if one wants to do some serious downwind sailing in a really
small vessel there is something to be said for heavy displacement and a
full keel. However, if the price for going small is going heavy, count me out!
Flying Dutchman
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Jim Manzari
John Wilson wrote:
>
> ....In fact, we got out of the situation - after three
> more bad knockdowns - by getting the bows into the breakers under
> storm jib alone. No heavy boat could have done this.
I am not sure what you mean by "heavy boat" (high disp-lwl?, heavy
weight?), but it is noteworthy that the much maligned (by some people)
Colin Archer type of boat (about the highest disp-lwl small sailing
boat I can think of), which was originally designed as a rescue boat,
had a remarkable record in very severe weather off the coast of Norway
(60N Lat). For instance, the Oskar Tybring, designed and built in
1895 by Colin Archer, was credited with assisting 102 craft and saving
329 men's lives. These vessels
"...when properly canvased and handled, have shown themselves
capable of beating off a lee shore in the strongest blow. One of their
remarkable features was the ability to tow four or five smaller
fishing boats off a lee shore under sail in bad weather."
--- J. Leather, Colin Archer and Seaworthy Double-Ender,
Stanford Maritime 1979--
> Please don't get me wrong. I'm not preaching that light boats are the
> answer for ocean passages. I'm just saying that they shouldn't be
> written off. If I had the money I'd be very tempted by a BIG
> high-tech ultralight as a shorthanded - or singlehanded for that
> matter - ocean cruiser. But the key is BIG. Without a lot of money
> though I'd go heavyish-displacement, longish-fin-keel-and-skeg-hung
> rudder etc. etc.
I think the choice might well be dictated by "where" you want to
travel. If I were headed for the Antarctic I would seriously consider
a steel boat of pretty strong (read heavy) construction.
If one were headed for a snow-bird anchorage in the Caribbean, one
might consider a Beneteua or Hunter.
If you planned to visit both places on your circumnavigation, which
would you select?
<good list of seamanship requirements snipped>
> ...The illusion that heavy boats will "protect" you is in my opinion
> an illusion. I believe "Sandjefiord" - a very heavy wooden
> Scandinavian 70 foot double-ender, was pitchpoled mid-Atlantic many
> years ago. I've seen US Coastguard photographs of a 60' schooner
> being rolled. Certainly "Tzu Hang", a classic 46 foot heavy
> displacement cruiser has been both rolled and pitchpoled, on
> separate voyages, in the same waters (off cape Horn).
Assuming we are both talking about the same photos, I would have to
disagree with your conclusions regarding the schooner event. The
schooner incident is actually the final throes of a old wooden ship
that has sprung its planks and is sinking. Capsize in this case
occurred due to flooding NOT wave forces *by themselves*. I think if
you look again at the photos you will see a USCG rigid-inflatable
coming into the picture. No RIB could ever be launched in hurricane
seas (or winds for that matter), without first suppressing the hugh
waves by maneuvering the CG cutter to create a calm within a circular
area around the schooner. In this instance, if we are thinking of the
same photos, your argument is not proven ("heavy is an illusion").
The size of the schooner proves nothing in this instance, except that
old wooden ships often spring their planks in heavy weather and
flounder.
I do agree that good seamanship can make a good job out of a bad
situation. If a skipper does not take action to slow the yacht when
running before large seas, there is a good chance that the boat will
fall into a hole or off the top of a very large wave. If my memory
serves, I think that is what happened in the first Tzu Hang
pitch-pole. I can't remember what happened in the second. In any
case the conditions were extreme. There may, sooner or later, come a
time when a cruiser may encounter a wave that it simply can't be
weathered.
A good example of the disastrous consequences of the inability to slow
or stop in heavy weather, is the experience of the yacht "Destiny", a
13.7m Norseman cutter designed at 12.5 tons, in the 1994 storm north
of New Zealand. The conditions were 75 knots (wave height not
specified in the account, but other boats reported 12-15m). They were
running under bare poles with "Sea Squid" drogue from stern keeping
speed at 6-8 knots(!!). Pitch-poled and rolled when boat fell off the
top of a wave. I wonder if the results would have been the same if
the boat had hove-to under try-sail and storm jib making a slick to
windward.
Jim Manzari
kpk...@acpub.duke.edu
By now many people following this newsgroup realize that Jim Manzari is
posting a lot of stuff that simply isn't true. This is not to say that
ALL of his viewpoints are utter rubbish, however he should be less
pompous and more honest.
Last week he posted, twice over, a list of boat characteristics and
challenged anybody to explain any benefits. He offered to post any
responses emailed to him. Well, I emailed an answer and I don't see it
posted, Jim! Guess this offer was just more of your bluster.
Jim Manzari wrote:
> Can anyone in this newsgroup explain what are the benefits to a
> bluewater cruising yacht, and its skipper and crew, to have any or all
> of the following features:
>
> Spade rudder
Reduces steering loads, thus saving wear and tear on gears, chains,
sprockets, sheaves; and epecially self-steerers. Those using
autopilots save electricity.
> Deep, narrow, thin fin keel
More efficient going to windward.
Increases stability.
> Vertical foreward hull sections- no intrinsic benefit
> Flat bottom hull
Increased initial stability
Reduced draft.
> Wide, shallow aft hull sections
Increased reserve buoyany aft.
Improved off-wind steering.
> Low freeboard
Reduced windage.
Increased strength of hull.
Easier access to/from dinghy and/or docks.
> Unbalanced or asymmetrical heeled waterlines
Huh?? Every boat has this characteristic. Where do you think form
stability comes from, the stork??
> Shallow or non-existent bilge space
Increased headroom for given hull dimensions.
Reduced chance of unobserved flooding.
> Swept-back spreaders- no intrinsic benefit, however a marconi rig
could be designed to benefit from needing less standing rigging
by use of this feature.
> Carbonfiber mast needing 3 or more spreaders- no intrinsic benefit
> 5 or more batten pockets in the main
Reduced wear and increased efficiency of mainsail- better performance
when reefed particularly.
Greater longevity of sail.
-Note- these benefits are maximized with full-batten sails.
> Battens in the head sails
See above. Is this supposed to be hypothetical? I don't see very many
boats *at all* with battened jibs.
>
> To put some scope around this question, please assume a husband and
> wife crew on a circumnavigation of about 5 years duration with
> excursions outside the tradewinds to regions such as New Zealand,
> Alaska, Chile, Sweden, for example. Please assume 6 months supply of
> fuel and food must be carried. 2 months supply of water. Please
> assume a general boat length limited about 32 to 45 feet LOA.
Glad you've set up some parameters. Should we expect less of your
rhetorical smartaleckry for this?
And wot's the deal with 6 months food/fuel and 2 months water? Do we not
shower? Are we carrying a watermaker? Or are we living in a Hornblower
novel again? "Mr. Bush, tell off a boat crew and swing out the casks..."
>
> I'll post a summary of replies, less names, for those who wish to
> reply via private email.
I gave you five days, and you did no such thing. Meanwhile you posted
more soapboxing. Hmmm... Does anybody *not* see a pattern here?
Fresh Breezes- Doug King
Joe Ozelis
While not a complete summary, I have tabulated all of the stability data
from every IMS certificate in my possesion - IMS, IOR, and CCA designs
are in this sample.
Anyone wanting to perform a more complete analysis is welcome to spend
some of their own money to back up their positions, by getting the info
from US sailing.
Design Year LPOS POS/NEG Remarks
(deg.) Stab. Ratio
------------------------------------------------------------------------
J/N 1-Ton (IOR) 1984 111.5 1.988 frac IOR design
Cook 41 (IOR) 1984 117.3 2.636 MH IOR
Block Island 40 1958 112.1 1.874 CCA design
Swan 391 SD 1987 112.4 2.186 Shoal-Draft
Nassau 45 1980's 113.0 2.284 Bob Perry design
Rhodes Reliant 41 yawl 1950's ? 122.8 ?
Rhodes 37 1950's 116 ? full-keel w/ CB
Frers 38 (Carroll Mar.) 1989 124.0 4.027 Early IMS w/8+' keel
IMX-38 (X-Yachts) 1992 115.6 2.392 IMS racer/cruiser
Schumacher 40 1994 122.5 3.753 IMS cruiser/racer
Tripp 36 1990 122.9 3.510 IMS R/C w/bulb keel
I think it is clear from this data sample (which is essentialy random, as I
used all of the data available to me, without making any cuts), that modern IMS
designs do indeed have favorable, and in fact, often superior stability numbers
than many "solid, conservative, classical" CCA-era yachts. I have little doubt
that the latest IMS design, with deep bulb keel and moderate beam, will
have LOPSes in the 122-128 range, adn rations of POS/NEG sability around 4-5.
Any blanket statement that modern racing designs exhibit poor stability as
witnessed by LPOS or POS/NEG is simply false.
Joe Ozelis
Sailboat Sales Co.
Performance Yacht Sales
www.sailboatsalesco.com
jktho...@earthlink.net
Excuse me, but the only pattern I see here is your steady stream of rude
posts in the past months. A couple of points about this one -
1. Spade rudders - "Reduces steering loads, thus saving wear and tear" you
said - spade rudders are often less robust and certainly more easily fouled
by lines and mooring cables. They will reduce the steering loads, however,
when they break off. See Hunter rudder stories -
http://home.earthlink.net/~jkthompson/Hunter.htm
2. Shallow bilges - "Reduced chance of unobserved flooding" you said - you
must be a yacht salesman to come up with an answer like this one. What's the
matter with a bilge and a bilge alarm? Have you even been on a bilge-less
boat that takes in a gallon of water - it's everywhere you don't want it to
be.
Don't bother telling me I don't have to read your posts. I only read them
when it looks like you're berating someone who knows more about cruising
than you do.
John
This newsgroup settles down and gets MUCH more rewarding to visit if you
employ your filters to weed out the megalomaniacs, office chair sailors,
wannabe naval architects, racers and everyone with an address ending in
"edu". It shrunk by 40% when I did that, and most of the remaining posts
are about matters actually related to cruising.
Paul Kamen
Joe Ozelis <joz...@enteract.com> writes:
>While not a complete summary, I have tabulated all of the stability
>data from every IMS certificate in my possesion - IMS, IOR, and CCA
>designs are in this sample.
--
Paul Kamen
Joe Ozelis <joz...@enteract.com> writes:
While not a complete summary...
Good work! Thanx for that compilation. Too bad we couldn't ask Jim about
the relative stability of the Block Island 40 v. the Schumacher 40 before
tipping the cards...
Anders Svensson
kpk...@acpub.duke.edu wrote
> Jim Manzari wrote:
> > Can anyone in this newsgroup explain what are the benefits to a
> > bluewater cruising yacht, and its skipper and crew, to have any or all
> > of the following features:
> >
> > Spade rudder
>
> Reduces steering loads, thus saving wear and tear on gears, chains,
> sprockets, sheaves; and epecially self-steerers. Those using
> autopilots save electricity.
This is not completely correct, Doug. You are referring to the advantages
of a *balanced* rudder - wich is quite achievable on skeg hung rudders as
well.
A spade rudder (as I see it) is a rudder mounted only in its own axle, and
have no attachments on any form of skeg or the keel itself. Properly
designed, it can be strong enough, but bending loads and dynamic axle
deformation cause sometimes stiffness - the opposite of what you propose.
Another quote:
> Should we expect less of your
> rhetorical smartaleckry for this?
>
> And wot's the deal with 6 months food/fuel and 2 months water? Do we not
> shower? Are we carrying a watermaker? Or are we living in a Hornblower
> novel again? "Mr. Bush, tell off a boat crew and swing out the casks..."
Please, Doug... Sometimes it rains, sometimes there is water available
ashore.
Even watermakers are part of the inventory these days. A ratio of water to
food/fuel of 1 to 3 may be completely reasonable. You may find or make
water - but you cannot find or make fuel or food as easy... BTW, if you
have a water maker, it need fuel (or food <g> ) to create freshwater...
Anders
kpk...@acpub.duke.edu
It's true that not all balanced rudders are spade rudders, and that it's
possible to have an unbalanced spade rudder, but I've never seen the
latter nor even drawings of one. However, I freely admit that I haven't
seen every boat in the world....
> > Jim Manzari wrote:
> > > Can anyone in this newsgroup explain what are the benefits to a
> > > bluewater cruising yacht, and its skipper and crew, to have any or all
> > > of the following features:
> > >
> > > Spade rudder
> kpk...@acpub.duke.edu wrote
> > Reduces steering loads, thus saving wear and tear on gears, chains,
> > sprockets, sheaves; and epecially self-steerers. Those using
> > autopilots save electricity.
> Anders Svensson wrote:
> This is not completely correct, Doug. You are referring to the advantages
> of a *balanced* rudder - which is quite achievable on skeg hung rudders as
> well.
Not entirely- a rudder on a skeg will not produce the same turning force
as efficiently, since it has to push the skeg sideways through the
water. A *well-designed* spade rudder produces more turning force for
less drag and helm effort. They typically work better throughout a wider
range of speeds and heeling angles, as well.
>
> A spade rudder (as I see it) is a rudder mounted only in its own axle, and
> have no attachments on any form of skeg or the keel itself.
Quite right.
> .... Properly
> designed, it can be strong enough, but bending loads and dynamic axle
> deformation cause sometimes stiffness - the opposite of what you propose.
I made the assumption that the rudder post and bearings would be
properly sized. The question never stated that poor design and shoddy
construction were a given.
Anders, there is a world of difference between your posts and Jim
Manzaris. He is condemning a whole class of boats (and the people who
sail them) simply on the grounds of prejudice. I have learned a lot from
this newsgroup, and hope to continue. This will be difficult if it
becomes a ballyhooing ground for a few would-be gurus of a specific type
of "cruising" in a specific type of boat.
Fresh Breezes- Doug King
kpk...@acpub.duke.edu
jktho...@earthlink.net wrote:
>
> Excuse me, but the only pattern I see here is your steady stream of rude
> posts in the past months.
I fail to see where I have been rude. Is there any profanity in my
posts? Personal attacks? Please give a definite example, or quit making
these false accusations. In either case, please stop emailing me about
it.
I have also never resorted to falsely crediting others with saying
things they never said.
> Don't bother telling me I don't have to read your posts. I only read them
> when it looks like you're berating someone who knows more about cruising
> than you do.
So how do you know if I'm berating someone without reading my posts?
BTW- I've actually been pretty kind to poor Jim. You obviously have
never seen REAL berating...
And on what basis do you conclude that you, or Jim Manzari, "knows more
about cruising" than I do? Do you need some sort of pedestal for your
self esteem, or for his?
Jim Manzari certainly knows a good bit less than he thinks he does. His
improper use of technical terms is a constant. Oh, yes, and when are we
going to see an answer from HIM on this? And on the 150-year-old frame
templates? And on the stability curves for his favorite cruising vessels
versus recent "racing" types?
Ah, well, at least I enjoy sailing...
Fresh Breezes- Doug King
Terry Schell
"Anders Svensson" <anders.-.ei...@swip.net> writes:
>kpk...@acpub.duke.edu wrote
<snip>
>This is not completely correct, Doug. You are referring to the advantages
>of a *balanced* rudder - wich is quite achievable on skeg hung rudders as
>well.
<snip>
I haven't seen any designs that have any significant balance area with
a skeg design. This could just be a lack of experience on my part,
but they do seem somewhat rare.
What designs are you thinking of?
Balanced rudders are, IMHO, a very good thing. They allow you to
increase the amount of boat control and rudder feel without increasing
the forces.
Terry
John S. Ward
kpk...@acpub.duke.edu wrote:
>
> It's true that not all balanced rudders are spade rudders, and that it's
OK, someone is going to have to explain this one to me. It's easy to
see
how to balance a spade rudder, but I can't for the life of me figure out
how you would do it with a skeg.
I've sailed some well-designed balanced spade rudders on lightweight
boats,
and they were a joy to steer. I've also sailed at least one boat with
an
unbalanced skeg rudder, and, being a heavy boat to begin with, the
forces
were just too large to handle comfortably. My wife couldn't drive at
all,
lacking sufficient body weight and upper body strength. And no, it had
nothing to do with sail trim. Just a badly designed boat, I guess.
-John
Anders Svensson
kpk...@acpub.duke.edu skrev i inlägg <352A23...@acpub.duke.edu>...
> It's true that not all balanced rudders are spade rudders, and that it's
> possible to have an unbalanced spade rudder, but I've never seen the
> latter nor even drawings of one. However, I freely admit that I haven't
> seen every boat in the world....
You may not have to look very far to se one... Check out a stern hung
dinghy rudder, and you will most probably se a "unbalanced spade rudder"...
> > Anders Svensson wrote:
> > This is not completely correct, Doug. You are referring to the
advantages
> > of a *balanced* rudder - which is quite achievable on skeg hung rudders
as
> > well.
>
> Not entirely- a rudder on a skeg will not produce the same turning force
> as efficiently, since it has to push the skeg sideways through the
> water. A *well-designed* spade rudder produces more turning force for
> less drag and helm effort. They typically work better throughout a wider
> range of speeds and heeling angles, as well.
As I have understood it there are virtues with both kinds.
The spade rudder has less wetted area for the same turning force and can
keep a effecient flow better at large angles (that is because the aft end
of the boat describes a circle when turning, and spade rudder can be turned
in its entirety into the water flow.
The skeg (or keel) hung rudder may have a better flow and stall less at
acute angles due to the "lead in" of the water flow by the skeg. It is also
true that the skeg is hindering the turn, but that is OTOH probably a part
of total course stability. The skeg protects the rudder, wich is important
- the rudder being a crucial piece of equipment.
> I made the assumption that the rudder post and bearings would be
> properly sized. The question never stated that poor design and shoddy
> construction were a given.
I accept that. I think that for a meaningful comparison real world
experience can be valued too. There are a lot of boats that have tried out
performance enhancing design features witout getting them right. We have a
few over here, I have heard "hunter" being said with weary voices at your
place...
It is also a question not only of proper design but also what can be made
consistly well and easy to maintain. A rudder supported by a skeg is easier
to make strong and durable, and also less prone to be destroyed or wedged
stuck by flotsam.
Both setups have virtues, as have both the Land Rover and the Porsche.
Anders
Anders Svensson
Terry Schell <tsc...@s.psych.uiuc.edu> wrote
>
> I haven't seen any designs that have any significant balance area with
> a skeg design. This could just be a lack of experience on my part,
> but they do seem somewhat rare.
>
> What designs are you thinking of?
I have one on my boat, a Björn Jensen design, Compass. The balance area is
not much, but it helps. After a short walk around the lay up area of our
marina, I saw at least 5 boats, among them a Rassy that has similar setups.
The rudder blade goes below the skeg and the balance area is put under and
in front of the foot (heel?) bearing
I suspect that you have seen this setup at your place too - maybe
"significant" is the operative word here. I am under the assumption that
you only need 5 % balance area (or so) to make a big difference to steering
forces.
Anders
Terry Schell
<snip>
>I have one on my boat, a Bjvrn Jensen design, Compass. The balance area is
>not much, but it helps. After a short walk around the lay up area of our
>marina, I saw at least 5 boats, among them a Rassy that has similar setups.
>The rudder blade goes below the skeg and the balance area is put under and
>in front of the foot (heel?) bearing
>I suspect that you have seen this setup at your place too - maybe
>"significant" is the operative word here. I am under the assumption that
>you only need 5 % balance area (or so) to make a big difference to steering
>forces.
I have to admit I haven't looked that carefully at the precise
placement of the bearings. They just always look like they are as far
forward as possible. I will check it out.
5% is certainly noticable... perhaps not quite significant because it
won't allow you to reduce the mechanical advantage needed to control
the boat. Of course, the skeg reduces the balance area in another way;
It is, in effect, the leading edge of the foil. This reduces
the Cl on the forward portion of the actual rudder, resulting in less
"balance" even if the area forward of the axis of rotation is the same
as a foil in an undisturbed flow.
BTW... I saw someone with a thin cable running from the bottom of a
spade rudder to a spot on the hull a couple feet in front of the
rudder. The owner got tired of cutting kelp off of the rudder and
thought this would solve the problem. I wonder if it would also
serve the collision protection function of a normal skeg? Anyone with
some experience?
Sincerely,
Terry
Lauri Tarkkonen
In <352A5773...@socrates.caltech.edu> "John S. Ward" <ward+...@socrates.caltech.edu> writes:
>kpk...@acpub.duke.edu wrote:
>>
>> It's true that not all balanced rudders are spade rudders, and that it's
>OK, someone is going to have to explain this one to me. It's easy to
>see how to balance a spade rudder, but I can't for the life of me
>figure out how you would do it with a skeg.
It is easy:
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB bottom of the boat
SSSSSSSSSSSSSSSSSS RRRRRRRR R = Rudder
SSSSSSSSSSSSSSSS RRRRRRRRR S = Skeg
SSSSSSSSSSSSS RRRRRRRRRR
SSSSSSSSSS RRRRRRRRRRR
SSSSSSSS RRRRRRRRRRRR
RRRRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRRRR
RRRRRRRRRRRRRRR
RRRRRRRRRRRRR
RRRRRRRRRR
RRRRRR
A part of the rudder, below the skeg is ahead of the rudderpost.
Of course you do not get a "perfect" balance this way, and you do not
have a skeg that is coming all the way down to the bottom of the
rudder, but you have skeg and some balancing in the rudder.
This does not mean, that I am supporting the idea of prefering
a skeg over a spade rudder without one.
>I've sailed some well-designed balanced spade rudders on lightweight
>boats, and they were a joy to steer. I've also sailed at least one
>boat with an unbalanced skeg rudder, and, being a heavy boat to begin
>with, the forces were just too large to handle comfortably.
>My wife couldn't drive at all, lacking sufficient body weight and
>upper body strength. And no, it had nothing to do with sail trim.
>Just a badly designed boat, I guess.
When discussing the differences and comparing the performance, we
should not compare bad spade rudders to good skeg hung rudders.
If the rudderstock is too light or the boat bends so that loadings
twist the bearings this is bad design. Those who tell that the skeg
hung rudders are strong and protect the rudder from breaking, should
go to some bigger repair yard and ask how many skegs and skeg hung
rudder bearings they repair every year. I have been following the
work on one of those, and there are plenty of them. Couple of years
ago, the Yaching World was sending a boat to the Atlantic Rally for
Cruisers and they had to withdraw the boat, because it was leaking
as the skeg was bending and opened a gap between the skeg and hull
when the boat was sailing on the other tack.
I have a spade rudder and tiller steering in my present boat and
after a small modification to the rudder I can turn it around 360
degrees and when I reverse, I turn it around 180 degrees and I can
motor backwards and have very good controll of my steering. It is
very usefull if I have to come backwards out from my berth and there
is a strong wind form either side, I have much better controll and
can steer the boat in reverse much easier. Of course real blue water
cruisers, who visit a harbour only once in three months and even
then prefer to stay out in anchor see no use of the improved manou-
verability of the boat. If they come to the dock once a year, they
can always get some small motor launch to help them in. :-)
- Lauri Tarkkonen
Jim Manzari
Just curious, why have I never seen a spade rudder on an airplane
(other than exotic military stuff)? In fact, most commercial aircraft
seem to favor skeg rudder with a fair amount of dorsal in front of the
skeg. Why?
One (potential) hazard of a tiller-controlled balanced rudder: When
backing down it is not unheard of for someone to be hurt by the
considerable force transmitted to the tiller. I would also guess that
heaving-to on a balanced rudder might expose the rudder shaft and
tiller or wheel setup to these same considerable forces when the boat
is thrown backwards. I remember participating in a rescue of someone
with broken ribs when I was in the Coast Guard for just this reason.
Jim Manzari
Anders Svensson wrote:
<snip>
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
>Just curious, why have I never seen a spade rudder on an airplane
>(other than exotic military stuff)? In fact, most commercial aircraft
>seem to favor skeg rudder with a fair amount of dorsal in front of the
>skeg. Why?
I don't want to get too much into stability and flight dynamics... but
an airplane rudder is not really similar in function to a boat rudder
(outside of the fact that they boat can create a yaw moment). Unless
something has gone horribly wrong the "leeway" of a plane should be
very, very, very small. Under normal flight regimes, the rudder could
actually be replaced with a larger static vertical stabilizer (but it
would have more drag due to larger size). In other words, the
vertical stab and rudder's primary purpose is to provide static and
dynamic stability not control.
The airplane elevator is more similar to the boat rudder in terms of
stability and control. Most aircraft do have all-moving horizontal
stabs (elevators)... although there are notable exceptions.
>One (potential) hazard of a tiller-controlled balanced rudder: When
>backing down it is not unheard of for someone to be hurt by the
>considerable force transmitted to the tiller.
Of course, this force would be *reduced* in a balanced design relative
to an unbalanced design. :-) This is an argument for a balanced
rudder.
I would also guess that
>heaving-to on a balanced rudder might expose the rudder shaft and
>tiller or wheel setup to these same considerable forces when the boat
>is thrown backwards. I remember participating in a rescue of someone
>with broken ribs when I was in the Coast Guard for just this reason.
Once again, work through the forces. You will find the *moment* about
the axis of rotation is reduced (in both forward and reverse) as the
shaft is moved back from the leading edge of the foil (at least until
it is around 28% aft for forward motion and 72% aft for forces in
reverse). Only this moment is transfered to the helm.
People can get overpowered by the tiller/wheel, particularly in
reverse. However, these forces are substantially reduced in a
balanced design. They are reduced even more in high-aspect ratio
designs... but I suppose that's another thread.
Sincerely,
Terry
Lauri Tarkkonen
>Just curious, why have I never seen a spade rudder on an airplane
>(other than exotic military stuff)? In fact, most commercial aircraft
>seem to favor skeg rudder with a fair amount of dorsal in front of the
>skeg. Why?
If you have the idea that all structural and aero-hydrodynamical
aspects should be similar in airplanes and sailing boats, you
are a bit lost. What is good or necessary for airplanes is not
necessary good or necessary for sailing yachts. If this is your
argument for a skeg hung rudder, you must be joking.
>One (potential) hazard of a tiller-controlled balanced rudder: When
>backing down it is not unheard of for someone to be hurt by the
>considerable force transmitted to the tiller. I would also guess that
>heaving-to on a balanced rudder might expose the rudder shaft and
>tiller or wheel setup to these same considerable forces when the boat
>is thrown backwards. I remember participating in a rescue of someone
>with broken ribs when I was in the Coast Guard for just this reason.
I already explained in my previous post, that I can flip my rudder
180 degrees around when reversing. I have a curved tiller and by
hoisting it in vertical position I can turn the rudder around 360
degrees and steer in the backward position.
Even if you have the skeg, there is the danger of the rudder being
slammed over 90 degrees and the tiller can hurt you. There is danger
that you break your bearings in the process as well.
After I modified my rudder so that I can turn it around I have
noticed that it is a veri usefull feature. Even if I only pull
the boat out from the dock with the buoyo line or the anchor rode
it is much easier to let the rudder rest in the reversed position.
When the foil is in the proper direction in regard to the movement
of the boat it steers the boat much more effectively.
In manouverability the spade rudder that can be turned around wins
hands down.
- Lauri Tarkkonen
Jean Somerhausen
Jim Manzari wrote:
>
> Just curious, why have I never seen a spade rudder on an airplane
> (other than exotic military stuff)? In fact, most commercial aircraft
> seem to favor skeg rudder with a fair amount of dorsal in front of the
> skeg. Why?
>
> backing down it is not unheard of for someone to be hurt by the
> considerable force transmitted to the tiller. I would also guess that
> heaving-to on a balanced rudder might expose the rudder shaft and
> tiller or wheel setup to these same considerable forces when the boat
> is thrown backwards. I remember participating in a rescue of someone
> with broken ribs when I was in the Coast Guard for just this reason.
>
>
> Anders Svensson wrote:
>
> <snip>
>
> > you only need 5 % balance area (or so) to make a big difference to
> > steering forces.
"half-skeg"), the force as much less when backing up than on the Tor 36
(steel version of the Little harbor 36). Once, tied up the wrong way (ie
facing upstream) at the dock in the river that leads to Rye in Sussex (I
have forgotten the name), where the flood comes in a 3-4 knots, the
force of the current that came in with a rush was such that it broke the
tiller of the Tor 36 (fortunately, I had a spare...)
John
Brian Grant
John Hapgood wrote:
>
<< snip >>
>
> But your correct that good nomenclature is a GREAT help. (as long as it's not
> taken too far :-)
>
Just watched a program on the History Channel about old schooners. The
largest had 7 masts and apparently there was great discussion on the
names of the masts. The crew called them 1,2,3,4,5,6,7 until the
captain decided to call them Monday, Tuesday ... Sunday.
Greg Jackson
Thomas Ling wrote:
>
> Recently I was at a meeting where the esteem naval architect, Mr. Bob
> Perry spoke of spade rudder. All his recent boats were spade rudders,
> light weight, D/L BELOW 200, fin keels with bulbs. His design of rudder
> and bearing support are so strong that he claimed the transom will tear
> out long before the rudder will break. What Lauri said was very much
> shared by Perry's opinion of the characteristic of spade rudder.
> IMHO not all spade rudders are built the same, in our 39ft. boat,the
> rudder stock is 5-1/2 inch. in diameter ( overkilled ); 3 inch of solid SS
> and 2-1/2 sheath of woven fiberglass. Going upwind is a dream, with sails
> properly trimmed the boat can track untouched for hours, that I believe
> is defined as balanced.
>
> cheers,Thomas Ling
> s/v SaiLing
>
Your posting has stimulated me to think about design issues in a much
different manner and brings to mind a number of design details I have
heard in the past. People criticize spade rudders because they are
weak. What Bob Perry is apparently saying is, OK, so we'll make a spade
rudder that is not weak. In other forums I have also heard proposals of
making the lower quarter of the rudder weaker so that, if grounding or
overloading breaks the rudder, it will break it in the middle and not at
the shaft, thereby retaining some steering potential to limp home.
Regarding the criticism of wrapping the rudder with line, I have also
heard proposals of running a small bar or pipe horizontal from the end
of the keel to the bottom of the spade rudder. This provides much of
the geometry advantages of a skeg, although none of the strength issues.
The bottom line here is that criticisms from the "Old Fart's" school of
thought should not lead us to all be sailing Captain Slocum's Spray, but
rather we should recognize the valid issues of the criticisms and look
to modern materials and methods to resolve the issues.
G. Jackson
s/v Compass Rose
Thomas Ling
OTNMBRD
In reading through this thread on rudders, as usual, I am finding some useful
information, but also as usual, I am finding myself occasionally confused due
to some of the terminology being used, when trying to draw a mental picture.
Mayhaps, we all need to be sure we are talking about the same thing, and with
that in mind, could someone define the following.....
Spade rudder, balanced rudder, unbalanced rudder, semi balanced rudder, skeg,
and bearings (gudgeons and pintles?).....hmmmm best through in ...rudder post.
I for one, have found thru experience, that I need be careful, when answering a
post, as sometimes my definition, is not always the modern or group definition.
For instance, when talking about mooring lines, the line leading from the
forward part of the boat, aft, to a cleat on the dock. Is this the:
A. Foreward, after/back spring
B. Foreward spring
C. After spring
D. Back spring
E. All of the above
<BG> OTNMBRD
John Hapgood
On 8 Apr 1998 01:46:34 GMT, otn...@aol.com (OTNMBRD) wrote:
>For instance, when talking about mooring lines, the line leading from the
>forward part of the boat, aft, to a cleat on the dock. Is this the:
>A. Foreward, after/back spring
>B. Foreward spring
>C. After spring
>D. Back spring
>E. All of the above
>
><BG> OTNMBRD
F. None of the above :-)
I pick "after bow spring" or just "bow spring" if you only have two springs
And then there's bow line, forward bow spring, forward bow breast, after bow
spring (mentioned), forward quarter spring, after quarter breast, after quarter
spring and last but not least, stern line.
But your correct that good nomenclature is a GREAT help. (as long as it's not
taken too far :-)
-
My Real Address is:
____ _
| __\_\_o____/_|
<[___\_\_-----<----------<jhap...@ix.netcom.com><
| o'
Paul Kamen
Jim Manzari <man...@bluewin.ch> writes:
>Just curious, why have I never seen a spade rudder on an
>airplane (other than exotic military stuff)? ...
Probably because airplanes don't user their rudders to turn. The primary
function of the vertical fin is directional stability. A small moveable
rudder element is adequate to balance yaw forces to maintain coordinated
flight. Also there is never a requirement to operate in local flow at a
large yaw angle, except during an intentional slip, in which case high
drag is usually the objective.
Note that many aircraft, including relatively low-tech light aircraft that
even I have flown (Cessna 177), have "spade" elevators. Unlike the rudder,
the elevator does have to operate over a wide range of local flow angles,
especially during takeoff rotation and landing flare.
>One (potential) hazard of a tiller-controlled balanced
>rudder: When backing down it is not unheard of for someone to
>be hurt by the considerable force transmitted to the tiller...
This is a hazard associated with any tiller-controlled rudder. The balance
area reduces this hazard somewhat, by moving the center of pressure (in
reverse) closer to the stock axis. It's reduced further with the very
deep, high-aspect rudders associated with modern race boats.
Jim Manzari
I'm reposting this, because it has somehow gotten mixed up with
several other threads which have nothing to do with the original
questions. Those who have replied to the original post need not
respond to this repost...
Can anyone in this newsgroup explain what are the benefits to a
bluewater cruising yacht, and its skipper and crew, to have any or all
of the following features:
Spade rudder
Deep, narrow, thin fin keel
Vertical foreward hull sections
Flat bottom hull
Wide, shallow aft hull sections
Low freeboard
Unbalanced or asymmetrical heeled waterlines
Shallow or non-existent bilge space
Swept-back spreaders
Carbonfiber mast needing 3 or more spreaders
5 or more batten pockets in the main
Battens in the head sails
To put some scope around this question, please assume a husband and
wife crew on a circumnavigation of about 5 years duration with
excursions outside the tradewinds to regions such as New Zealand,
Alaska, Chile, Sweden, for example. Please assume 6 months supply of
fuel and food must be carried. 2 months supply of water. Please
assume a general boat length limited about 32 to 45 feet LOA.
I'll post a summary of replies, less names, for those who wish to
reply via private email.
Thanks in advance,
Jim Manzari
Anders Svensson
He he he...
OTNMBRD <otn...@aol.com> wrote
> In reading through this thread on rudders, as usual, I am finding some
useful
> information, but also as usual, I am finding myself occasionally confused
due
> to some of the terminology being used, when trying to draw a mental
picture.
> Mayhaps, we all need to be sure we are talking about the same thing, and
with
> that in mind, could someone define the following.....
Spade rudders
Unbalanced
Balanced
Semi balanced
Fully balanced
Skeg hung rudders
Full skeg
Half/part skeg
Unbalanced
Balanced
Semi balanced
Fully balanced
Dont forget keel hung rudders...
Anders
JBChalais
kpk...@acpub.duke.edu wrote:
>
> It's true that not all balanced rudders are spade rudders, and that it's
> latter nor even drawings of one. However, I freely admit that I haven't
> seen every boat in the world....
A couple that might fit in the un-balanced catagory are the old early
80's Perason 37 IOR. Drove like a truck without power steering. And
the Catalina 36. Although I don't think the rudder is a spade...more an
eliptical...it isn't skeg hung and you need lots of umph to move them.
--
mailto:jcha...@ns.net Sacramento,Ca.
SV:Hind Sight doc#691808 PORT:San Francisco
HAM:KD6UOT, SSB:WAO4699, LAT38 36'658"N LON121 19'474"W
"water is very hard at 32deg and 150mph so stay warm and go slow"
Anders Svensson
Greg Jackson <jac...@itis.com> wrote:
> /Tomas Ling post snipped/
> Your posting has stimulated me to think about design issues in a much
> different manner and brings to mind a number of design details I have
> heard in the past. People criticize spade rudders because they are
> weak. What Bob Perry is apparently saying is, OK, so we'll make a spade
> rudder that is not weak.
Well, he is not the first one to say so, I assure you. No boat designer is
probably making a 'weak' part of their design free willing, so to say. What
amazes me is that even in this day designers/naval architects have so very
hard to get things right the first time - strengthwise. Some mean onlookers
may even say "second" or "third" time... Going for overbuilt and oversized
is *one* answer, but really, we should be able to take advantage of the
evolution even if we are cruisers...
Why is lacking strength such a problem? Do we not know and understand
enough of boat mechanics to make it right, first time? This is not
unthinkable at all - automotive manufacturers still do structal misdesigns
sometimes, in spite of very thorough calculations.
It still seem that some boat designers are just 'designers' - they build
boats by designing their shape, and not so much by determining loads and
puttting reinforcements in the right place. Sailboat construction seem also
to be an area where form is much more important than structure - not only
designers but also builders and customers share the responsibility for
this.
Now, this is an issue where I would like to hear what Paul has to say. I
hope that he can tell us that this is not necessary to "build by trial and
error" - and maybe also make some good arguments for going to a proper
engineer/naval architect for boat design.
> In other forums I have also heard proposals of
> making the lower quarter of the rudder weaker so that, if grounding or
> overloading breaks the rudder, it will break it in the middle and not at
> the shaft, thereby retaining some steering potential to limp home.
Right. Thats giving in to the thougt that there is no way to dimension them
correctly. The idea is not bad, but how on earth would anyone want to trust
this ploy if the designer cannot find a way of building his rudder
correctly in the first place...
> Regarding the criticism of wrapping the rudder with line, I have also
> heard proposals of running a small bar or pipe horizontal from the end
> of the keel to the bottom of the spade rudder. This provides much of
> the geometry advantages of a skeg, although none of the strength issues.
The idea is not bad, and it would help with some strength too. But the idea
with a proper constructed skeg is to add to the strength of the hull by
adding a tiny bilge all the way aft to rudder , not only to be a bearing
point for the rudder blade is quite correct. The skeg (or half-skeg) is
part of a hull design concept and should not be thought of only as a way to
hang the rudder - so to say.
One of the good sides with the spade rudder is (if it can be rotated 360
degrees) is that weed and stuff can fairly easy be freed, just by turning
the rudder around. It also have superior hydrodynamic propertys, and can be
shaped more optimally for its function and destrouing some of those
advantages by adding a drag inducing rod makes not much sense. That rod,
BTW can be a big problem for the rudder too, if you bend it.
> The bottom line here is that criticisms from the "Old Fart's" school of
> thought should not lead us to all be sailing Captain Slocum's Spray, but
> rather we should recognize the valid issues of the criticisms and look
> to modern materials and methods to resolve the issues.
Quite right!
So, let us all not forget that most OF's in fact are sailing yesterdays
state of the art boats - so to say... Skeg hung rudders, short or fin
keels, aluminium masts - all were highly suspect for cruising 30-40 years
ago.
>
> G. Jackson
>
> s/v Compass Rose
Anders
Terry Schell
"Anders Svensson" <anders.-.ei...@swip.net> writes:
<snip>
>Why is lacking strength such a problem? Do we not know and understand
>enough of boat mechanics to make it right, first time? This is not
>unthinkable at all - automotive manufacturers still do structal misdesigns
>sometimes, in spite of very thorough calculations.
In any mechanical engineering course you will deal with this problem.
Your calculations can be "spot on" but you you still need test to
destruction (i.e., trial and error) methods. There are two main
reasons for this a) off-design usage and b) variance in
manufacturing/materials quality.
You might find the hull "oil-canning" and conclude that the hull was
not built strong enough... what is not mentioned is that someone
rammed a dock with the boat 3 years ago and damaged the hull. It is
impractical to design a hull to withstand all collisions without
damage. The hull was designed right, the usage was not as designed.
Alternatively, the hull oil-cans and what was not mentioned is that
the builder did the layup at the "wrong" tempature. Good design, but
the designer didn't expect that much variance in the actaully building
method.
Terry
OTNMBRD
>
>F. None of the above :-)
>
>I pick "after bow spring" or just "bow spring" if you only have two springs
>
>
>And then there's bow line, forward bow spring, forward bow breast, after bow
>spring (mentioned), forward quarter spring, after quarter breast, after
>quarter
>s
<G> You prove my point........actually, in my area, the answer is "E", with "A"
being the most technically correct, for whatever reasons.........no matter, as
long as those on your boat are aware of the terminology you use, and you know
that others may use different terms.
But I digress....One term I'm not sure of in this thread, is SKEG.
For me, this refers to the after part of the keel, extending under the
propellor, supporting the sternpost.........something you don't find on too
many " modern" designs, and knowing this term is still in use, with possibly
expanded meaning, I admit to scratching my head, at times when hearing it used
and not fully understanding what someone may be trying to say.
This post is not meant to nit-pick, or criticize........I'm still working on my
learning curve, looking for information.
OTNMBRD
Paul Kamen
Anders Svensson <anders.-.ei...@swip.net> writes:
>...Now, this is an issue where I would like to hear what Paul
>has to say. I hope that he can tell us that this is not
>necessary to "build by trial and error" - and maybe also make
>some good arguments for going to a proper engineer/naval
>architect for boat design...
Rudders are a special problem because the standard design methodology
contains a serious error.
The basic design procedure is to check the maximum possible lift
coefficient before stall (usually obtained from a book of airfoil data),
multipy by area, speed squared and density, and divide by 2 to get
maximum lift force. That becomes the design load.
The trouble is, that book of standard airfoil data only gives forces for
steady-state conditions. It shows a maximum Cl of maybe 1.2 at most. BUT -
if the rudder is pumped hard, it's possible to create much higher
transients. I've seen data indicating a Cl as high as 3.0 is possible
from a rudder blade of normal porportions.
The effect of pumping is probably much more severe with spade rudders
than with skeg or keel-mounted. Oscillationg flow around a locked rudder
might also produce a similar effect.
Anders Svensson
Thanks Terry - this is about as far I am able to come by myself too.
Paul also gave me a reasonable and plausible (to me, at least) explanation
why conventional design methods can make a rudder (any rudder)
underengineered - wich in a way was enlightening.
I also can understand that designing a rudder to withstand hitting a log
(tree trunk) in 8+ knots will be tricky, at best and that no guarantee can
be given - still we know that this may happen and may feel uneasy about it.
I also knew that fluctuating (oscillating) loads can lead to stress
fatigue, and that stainless steel (as used for rudder stocks) is fairly
easy stressed.
Would I be completely obnoxious to want a *proper naval architect* to know
about these matters in detail and design my (or your, or anybodys) boat
correctly ? I dont want to be the one 'testing to destruction" (gee, I am
beginning to sound like Jim, don't I...) - but I can probably be trusted
to mot misuse it - that is, if misuse is defined in some sensible or
understandable way - like bumping my new Sleek45 into concrete pontoons...
Terry Schell <tsc...@s.psych.uiuc.edu> skrev i inlägg
<6gg8qh$17l$1...@vixen.cso.uiuc.edu>...
david
Greg Jackson wrote:
> Thomas Ling wrote:
> >
> > Recently I was at a meeting where the esteem naval architect, Mr. Bob
> > Perry spoke of spade rudder. All his recent boats were spade rudders,
> > light weight, D/L BELOW 200, fin keels with bulbs. His design of
> Your posting has stimulated me to think about design issues in a much
> different manner and brings to mind a number of design details I have
> heard in the past.
> The bottom line here is that criticisms from the "Old Fart's" school of
> thought should not lead us to all be sailing Captain Slocum's Spray, but
> rather we should recognize the valid issues of the criticisms and look
> to modern materials and methods to resolve the issues.
>
>
> s/v Compass Rose
Very well said !!
David Lomas
SV Aegis ( 28' Aloha)
Rodney Myrvaagnes
On Tue, 07 Apr 1998 22:41:43 -0500, Greg Jackson <jac...@itis.com>
wrote:
t. People criticize spade rudders because they are
>weak. What Bob Perry is apparently saying is, OK, so we'll make a spade
>rudder that is not weak.
Actually, that is what most good production boats do. How many
production boats have a spade rudder break? Let's worry about real
problemms. THere are plenty of those.
Jim Manzari
Joe Ozelis wrote:
>
> While not a complete summary, I have tabulated all of the stability data
> from every IMS certificate in my possesion - IMS, IOR, and CCA designs
> are in this sample.
I'm glad you have brought up this issue again. You have forced me to
look deeper than I might otherwise have done. Your data and the
numbers that I have been able to locate myself, have resolved any
doubts that I might have had in this matter. Thanks to you, I am now
strongly convinced that *I* (speaking only for myself) will never
consider, for ocean-crossing, long-term, blue-water cruising, any IMS
rated racing design or any boat that is a derivative of an IMS design,
ie, the so-called cruiser/racer, racer/cruising or "performance"
cruiser.
I am aware, from the stand point of capsize risk, there exists a wide
range of stability values among the IMS fleet, some very low and some
very high. The "average" IMS boat, however, is not very resistant to
capsize (see below for verification of this statement). Of course, I
do not begrudge those who wish to go to sea in this "average" IMS boat
for either cruising or racing. That is entirely their own personal
decision and responsibility.
I am aware that the size of a boat is important when considering risk
of capsize. The context of what follows is limited to boats in the
30-50 foot LOA range. The context is further limited to a husband and
wife team. Not the strong, large, semi-professional or professional
racing crews typically present when IMS fleet boats are raced in the
ocean or around the buoys. My comments are to be taken in the context
of oceanic sailing in remote areas of the world where weather reports
are unavailable and where rescue is not an available option. I am
assuming that the husband and wife crew will rely entirely on their
own resources and experience.
----
Turning to the numbers you have provided...
First of all, I'm puzzled about one thing: As a dealer for Island
Packet and Mumm boats, why did you not show us the stability numbers
and curves for these boats? In an earlier post to this newsgroup you
stated that this kind of stability data is readily available from the
manufacturer. It should have been easy for you, a dealer in these
boats, to obtain the necessary information. Why did you chose not to
show the numbers for these boats?
The issue of cruising design stability vs racing design stability
could easily be resolved if you had shown us the stability numbers and
curves for these diametrically opposed boat types.
Why this obvious omission of comparative data between Mumm and Island
Packet designs?
Joe Ozelis wrote:
>
> Anyone wanting to perform a more complete analysis is welcome to spend
> some of their own money to back up their positions, by getting the info
> from US sailing.
I think I've said this before: One has to wonder why fundamental
safety information has to be purchased by the consumer/sailor. It
seems obvious that this kind of information is important for
consumer/sailors to know and understand, in advance of the purchase of
an individual boat, or prior to the acquisition of an instance of a
particular class of boats.
In this age of easy data dissemination, this kind of safety data
should be on the Internet for all to look at.
Who could argue with this idea?
----
Joe Ozelis wrote:
>
> Design Year LPOS POS/NEG Remarks
> (deg.) Stab. Ratio
> ------------------------------------------------------------------------
> J/N 1-Ton (IOR) 1984 111.5 1.988 frac IOR design
> Cook 41 (IOR) 1984 117.3 2.636 MH IOR
> Block Island 40 1958 112.1 1.874 CCA design
> Swan 391 SD 1987 112.4 2.186 Shoal-Draft
> Nassau 45 1980's 113.0 2.284 Bob Perry design
> Rhodes Reliant 41 yawl 1950's ? 122.8 ?
> Rhodes 37 1950's 116 ? full-keel w/ CB
> Frers 38 (Carroll Mar.) 1989 124.0 4.027 Early IMS w/8+' keel
> IMX-38 (X-Yachts) 1992 115.6 2.392 IMS racer/cruiser
> Schumacher 40 1994 122.5 3.753 IMS cruiser/racer
> Tripp 36 1990 122.9 3.510 IMS R/C w/bulb keel
>
> I think it is clear from this data sample (which is essentialy
> random, as I used all of the data available to me, without making
> any cuts), that modern IMS designs do indeed have favorable, and in
> fact, often superior stability numbers than many "solid,
> conservative, classical" CCA-era yachts.
Your assertion regarding modern IMS designs is certainly not "proven"
by this very small "random" sample. It may be preferable for a
prospective buyer to follow the advice of a qualified expert in this
matter:
"As for the stability range, several yachts in the IMS fleet had a
positive righting moment up to 180-deg while there were some other
yachts which developed negative stability at 100-deg of heel. The
average was 122-degrees, which, as we have seen above, must be
considered a relatively low value from a safety point of view."
---Prof. Lars Larsson, page 52
"Principles of Yacht Design",
1994, Adlard Coles Nautical--
Note: "The average <of IMS FLEET> was 122-degrees...considered a
relatively LOW value from a SAFETY point of view."
Prof. Larsson is, apparently, one of Terry Schell's favorite nautical
architects. He gave the following testimonial:
"I have no disagreement with Larsson. The Larsson and Eliasson
text is probably one of the best primers for Yacht Design every
written.
---Terry Schell, rec.boats.cruising, 5 April 1998---
The Schumacher 40 (one of Paul Kamen's (fishmeal's) oft-recommended
designers) and IMX-38, which are listed above as cruiser/racer and
racer/cruiser (what's the difference?), seem to be prototypical of
Prof. Larsson's "relatively low value from a safety point of view".
I should like, also, to point out that your sample is contaminated by
several center-board or shoal-draft boats (Block Island 40, Swan 391
Shoal Draft, Rhodes 37 CB, and possibly the Rhodes Reliant 41 and
Nassau 45). Knowledgeable sailors know that center-board and
shoal-draft boats carry their ballast much higher up than fin or long
keel boats and are, therefore, generally more "tender".
Your conclusions are very much weakened by the use of these types of
boats.
----
Joe Orelis wrote:
>
> I have little doubt that the latest IMS design, with deep bulb keel
> and moderate beam, will have LOPSes in the 122-128 range, adn
> rations of POS/NEG sability around 4-5.
Although slight variations in angle of vanishing stability are
probably meaningless, it needs to be pointed out that the average of
the your "random" sample of the four (4) IMS boats is 121 degrees
(slightly below Prof. Larsson's low safety value), not your "wishful"
122-128 degrees. Also the average of the ratios of stability areas is
3.4, not your "wishful" 4-5 range.
For those who may have been following this thread an explanation is in
order regarding angle of vanishing stability. The following is a
reasonable description extracted for Yachting Monthly. This
description is included with each rare display of the stability curves
accompanying some boat reviews.
"Every boat has a range of positive stability, when she will right
herself when heeled; also a range of negative stability, over which
she will remain upside down until external forces (a wave) cause her
to come upright. The so-called GZ curve plots these ranges and
indicates the angles of maximum and vanishing stability, the point at
which the boat inverts (capsizes, rolls).
The GZ curve is not the whole story though. It is a static
calculation which gives us some idea of how likely a boat is to be
knocked down but cannot tell us how she will perform at sea. Other
factors influence stability, among them beam, ballast ratio, topside
height, superstructure volume, rate of water intake into a submerged
hollow mast, and center of gravity.
And always be aware that any boat can be capsized in the severe
conditions. Also bear in mind that the weight of stores and where and
how securely they are stowed can affect the stability of the boat."
Keep in mind for the remainder of the discussion:
- Higher LPOS (angle of vanishing stability) is better (safer).
- Higher POS/NEG (positive to negative stability) is better (safer).
----
Here is my contribution to this debate. The numbers in brackets in
the remarks column indicate the source of this information. I believe
this information is true, but can not, of course, guarantee it.
LPOS POS/NEG
Design Year (deg) Stab. Ratio Remarks
-------------------- ---- ----- ------------ ----------------------------
Contessa 32 1979 155 77.0 Fastnet survivor case study [1]
Grimalkin 1979 115 3.2 Fastnet disaster case study [1]
Running Tide 1970 139 13.0 Built before IOR intro [2]
IR 12-meter 197? 180 n/m Inter. Rule 12-meter [2]
Westerly Ocean 33 1997 143 20.6 Purpose-designed cruiser [4]
J-42 1997 133 8.6 Fast Offshore cruiser [5]
Navy 44 199? 129 6.7 Training Yacht [6]
Beneteua Oceanis 351 1994 118 3.1 Modern racer/cruiser [7]
Alden 43/45 1994 120 3.2 Modern shoal draft cruiser [8]
Dufour 30 Cl. 199? 115 2.9 Modern racer/cruiser [3]
Forgus 37 1998 130 21.0 Modern purpose-designed cruiser [9]
--------------------------------------------------------------------------
Now let's look at the consolidation of the two tables sorted by FPOS
(angle of vanishing stability).
Please note the important break point at Joe's "wished-for" high end
of FPOS (angle of vanishing stability) of 128. Please note the only
likely cruising yachts below FPOS = 128 are shoal draft boats, a
single Perry design, and the Rhodes Reliant 41. My guess is the Perry
and Rhodes are also both center-board boats. I've marked the known
center-board and shoal draft boats with (*).
Please note the similarity of POS/NEG values between the Grimalkin (a
well studied failure in the Fastnet race) and the current IMS-inspired
designs. Note, in particular, the number of modern racer/cruiser
designs that have similar (or worse) values compared to Grimalkin.
Please note that only when you get to the Frers 38 or Navy 44 do the
values for area ratio get anywhere close to Joe's "wished-for" 4-5.
It is apparent from this arguably small sample of stability data that
purpose-designed cruising boats are much better in terms of minimal
risk of capsize than current IMS or cruiser/racer designs.
Boats derived from racing designs and marketed as "cruiser/racer",
"racer/cruising", or "performance cruiser" may not be what you want in
terms of stability for long-term blue-water cruising.
LPOS POS/NEG
Design Year (deg) Stab. Ratio Remarks
-------------------- ---- ----- ------------ ----------------------------
J/N 1-Ton (IOR) 1984 111 2.0 frac IOR design
Block Island 40 1958 112 1.9* CCA design
Swan 391 SD 1987 112 2.2* Shoal-Draft
Nassau 45 198? 113 2.3 Bob Perry design
Grimalkin 1979 115 3.2 Fastnet disaster case study [1]
Dufour 30 Cl. 1997 115 2.9 Modern racer/cruiser [3]
Rhodes 37 1950 116 ?* full-keel w/ CB
IMX-38 (X-Yachts) 1992 116 2.4 IMS racer/cruiser
Cook 41 (IOR) 1984 117 2.6 MH IOR
Beneteua Oceanis 351 1994 118 3.1 Modern racer/cruiser [7]
Alden 43/45 1994 120 3.2* Modern shoal draft cruiser [8]
Schumacher 40 1994 123 3.8 IMS cruiser/racer
Tripp 36 1990 123 3.5 IMS racer/cruiser w/bulb keel
Rhodes Reliant 41 195? 123 ?
Frers 38 (Carroll M) 1989 124 4.0 Early IMS w/8+' keel
Navy 44 199? 129 6.7 Training Yacht [6]
Forgus 37 1998 130 21.0 Purpose-designed cruiser [9]
J-42 1997 133 8.6 Purpose-designed cruiser [5]
Running Tide 1970 139 13.0 Built before IOR intro [2]
Westerly Ocean 33 1997 143 20.6 Purpose-designed cruiser [4]
Contessa 32 1979 155 77.0 Fastnet survivor case study [1]
IR 12-meter 197? 180 n/m Inter. Rule 12-meter [2]
-------------------------------------------------------------------------
Notes:
n/m = not meaningful, no negative curve.
[1] "Seaworthiness, The Forgotten Factor", Prof. C. A. Marchaj, 1996,
Revised Edition, Adlard Coles Nautical, original source RORC and RYA
Fastnet Report.
[2] "Desirable and Undesirable Characteristics of Offshore Yachts",
Chapter 3, Avoiding Capsize: Research Work, Kark L. Kirkman and
Richard C. McCurdy, Technical Committee of the Cruising Club
of American, 1987, Norton Publishing
[3] "Yachting Monthly", December 1997, page 85
[4] "Yachting Monthly", January 1997, page 61
[5] "Cruising World", January 1997, page 37, see this page
for an exemplary description of an offshore yacht.
All builders should emulate this style of advertising, IMO.
[6] "Cruising World", January 1997, page 37
[7] "Cruising World", August 1994, page 80
[8] "Cruising World", July 1994, page 74
[9] "Yachting Monthly", March 1998, page 89
----
Joe Ozalis wrote:
>
> and in fact, often superior stability numbers than many "solid,
> conservative, classical" CCA-era yachts
It is pure nonsense to believe that a Block Island 40 (a center-board
boat with its ballast located much higher than in normal keel boats)
is representative of "solid, conservative, classical" CCA-era boats?
Same problem with using the Swan shoal draft boat to make your case.
Probably the same problem with Nassua 45 and Rhodes Reliant.
----
Joe Ozalis wrote:
>
> Any blanket statement that modern racing designs exhibit poor stability as
> witnessed by LPOS or POS/NEG is simply false.
>
> Joe Ozelis
>
> Sailboat Sales Co.
> Performance Yacht Sales
> www.sailboatsalesco.com
Here's a blanket statement for you...
"Some modern ocean racers, and the cruising boats derived from
them, are dangerous to their crews."
---Olin J. Stephens II of Sparkman & Stephens,
"Desirable and Undesirable Characteristics of
Offshore Yachts", The Technical Committee of the
Cruising Club of America", 1987, Norton Publishing---
And another blanket statement...
"Admittedly, sensible, sober and prudent cruising owners have been
alerted that this fashion <of racing design> may contaminate yacht
design in general; as a result many boat buyers nowadays
'...cannot properly distinguish an honest, sturdy, and
long-lasting cruising boat from a flimsy, unseaworthy and
short-lived racer'."
---Prof. C. A. Marchaj, "Seaworthiness, The Forgotten
Factor", Revised Edition, 1996, Adlard Coles Nautical---
Speaking of blankets, Joe, I hope you don't mind if this child
continues to observe that the Emperor is still naked and seriously in
need of said blanket!
Jim Manzari
Anders Svensson
I think that te easiest way to convince you that this extremely simplifed
evaluation model is simply not working by pointing out that the "best boat"
according to these numbers will be a International 12 meter racing yacht.
What all this boils down to, is that with the right set of measurements,
almost any boat can be proved a true cruiser. Correlation between some
singled out measurements and cruising ability can easily be achieved, and
this is one of the most common statistical traps to fall in.
If I suggest that good cruising sailboats can be chosen by using fore stay
diameter, rudder area, propeller axle diameter and pulpit tube thickness as
criteria, I would possibly not go much wrong either. Throw in toilet seat
diameter and the size and number of frying pans carried too - and it will
be a sure-fire formula... :-)
But I am quite sure Jim will find a good, strong and nice boat with his set
of criteria - some of them even to my taste. But the operative word is
taste, I think.
Anders
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
<snip>
>doubts that I might have had in this matter. Thanks to you, I am now
>strongly convinced that *I* (speaking only for myself) will never
>consider, for ocean-crossing, long-term, blue-water cruising, any IMS
>rated racing design or any boat that is a derivative of an IMS design,
>ie, the so-called cruiser/racer, racer/cruising or "performance"
>cruiser.
> "As for the stability range, several yachts in the IMS fleet had a
> positive righting moment up to 180-deg while there were some other
> yachts which developed negative stability at 100-deg of heel. The
> average was 122-degrees, which, as we have seen above, must be
> considered a relatively low value from a safety point of view."
By your own statement you not would consider any IMS rated boat for
cruising because of stability concerns... even one of the designs with
180-deg stabilty? You make no sense. No one forces you to use the
median IMS boat.
It is also worth mentioning that in 1990 when Larsson collected this
data many of the boats with certificates were *not* designed to the
IMS rule. Many were designed to the IOR rule which (as everyone has
mentioned) created boats with lower than ideal stability. Larsson knows
better than to make the error of concluding something about the IMS
rule from this data. I suggest you follow his lead.
You should also remember that later IMS designs are generally more stable
than earier designs. The fact remains that IMS does not, in any way,
encourage low stability boats.
<snip>
> LPOS POS/NEG
>Design Year (deg) Stab. Ratio Remarks
>-------------------- ---- ----- ------------ ----------------------------
>Contessa 32 1979 155 77.0 Fastnet survivor case study [1]
>Grimalkin 1979 115 3.2 Fastnet disaster case study [1]
>Running Tide 1970 139 13.0 Built before IOR intro [2]
>IR 12-meter 197? 180 n/m Inter. Rule 12-meter [2]
>Westerly Ocean 33 1997 143 20.6 Purpose-designed cruiser [4]
>J-42 1997 133 8.6 Fast Offshore cruiser [5]
<snip>
I love the fact that you call the J-42 a fast offshore cruiser. That
is pretty damn funny. It is a very slightly adapted version of a
racing design, marketed as a cruiser. I think you must be making
your "remarks" after looking at the LPOS since the J-42 is as much
a "racer/cruiser" as the Oceanis.
BTW... You are really screwing up the stability ratio. For some of
these boats you are reporting the "ratio of areas" and for other you
are reporting the "ratio of maximums". These are on very difference
scales.
<snip>
>It is apparent from this arguably small sample of stability data that
>purpose-designed cruising boats are much better in terms of minimal
>risk of capsize than current IMS or cruiser/racer designs.
...Especially when you get to label anything with high stability as a
"purpose-designed cruiser" and re-label boats that are marketed as
cruisers (Oceanis is the cruising version of the Bent. designs). If
that isn't biased enough, you throw out any "racers" that don't fit
your hypothesis (e.g., 12 meter).
You might choose to avoid a boat because of a 122 degree LPS.
That is your choice. However, you should mention that the oceans
(including the southern ocean) are safely sailed everyday by boats
with an LPS of 122 or less. I agree that, all other things being
equal, a larger angle of LPS is better, however, prudent seamen
have safely sailed these "unsafe" boats all around the world. Of all
the things that could kill you at sea, a LPS of 122 in a 45 foot boat
is way, way down on the list. For instance, I would take a boat with
an LPS of 122 with a wx fax over a boat with an LPS of 150 without the
weather info. I would rather sailing in a boat I find fun to sail,
even if it means that I feel I should avoid hurricane areas. There
are multiple ways to reduce risk to a level that is 'safe enough.'
If you don't think so, then we should only drive tanks... or perhaps
we should just stay at home where it is really safe.
Sincerely,
Terry Schell
Jim Manzari
Terry Schell wrote:
>
> vertical stab and rudder's primary purpose is to provide static and
> dynamic stability not control.
This looks like a good argument for a skeg and rudder combination on a
cruising boat. Cruising skippers tend to like going in a straight
line for thousands of miles while being pushed about by waves without
wearing down the crew or burning out the autopilot.
> Once again, work through the forces. You will find the *moment* about
> the axis of rotation is reduced (in both forward and reverse) as the
> shaft is moved back from the leading edge of the foil (at least until
> it is around 28% aft for forward motion and 72% aft for forces in
> reverse). Only this moment is transfered to the helm.
Sounds good theoretically. Why don't you work out and tell us about
the comparative level of forces experienced by both spade and skeg
rudders while hove-to in a 45-knot gale. Assume the boat is
periodically thrown backwards on its rudder a distance equal to 1/10
wave length, its full-load displacement is 30,000 pounds, significant
wave is height of 30 feet, hove-to angle 50-degrees off the wind and
sea. Then with your analysis in hand, bluewater skippers can select
the rudder style that minimizes cost and maximizes reliability and
maintainability.
Jim Manzari
Jim Manzari
Paul Kamen wrote:
>
> Probably because airplanes don't user their rudders to turn. The primary
> function of the vertical fin is directional stability.
I gather that you are giving a good reason for the lack of directional
stability that frequently leads to a broach in so many spade rudder
boats. Sounds like a skipper who wants to minimize the possibility of
a steering disaster in his cruising boat would want to follow the lead
of aircraft design and make sure a skeg is part of the rudder
assembly.
Jim Manzari
Jim Manzari
Lauri Tarkkonen wrote:
>
> If you have the idea that all structural and aero-hydrodynamical
> aspects should be similar in airplanes and sailing boats, you
> are a bit lost. What is good or necessary for airplanes is not
> necessary good or necessary for sailing yachts. If this is your
> argument for a skeg hung rudder, you must be joking.
Am I missing something here? Have you never heard of NACA/NASA wing
sections. I've seen them all over in boats yards for the past 25
years. You might want to get a copy of "Theory of Wing Sections", Ira
Abbot, Dover Publications, and browse the various <air> foil sections
that are currently used in yacht design -- mightily bored you will be!
No, I was not joking!
> After I modified my rudder so that I can turn it around I have
> noticed that it is a veri usefull feature. Even if I only pull
> the boat out from the dock with the buoyo line or the anchor rode
> it is much easier to let the rudder rest in the reversed position.
> When the foil is in the proper direction in regard to the movement
> of the boat it steers the boat much more effectively.
Very interesting, but not, I'm afraid, very high on the list of
priorities for a bluewater cruiser (subject of this thread). Also, I
can't think of a single cruiser that I met during my last 4 year
voyage that had this feature. Only a very few boats had tillers and
these were much too long to clear the backstay, if my memory serves.
> In manouverability the spade rudder that can be turned around wins
> hands down.
You might find it fun and satisfying to learn how to handle your boat
in all conditions with any kind of rudder -- it's part of that
accumulation of experience called seamanship. Good dockings are
called "one-bell" landings by Navy and Coast Guard skippers and are
the mark of a superb skipper. Military skippers pride themselves on
their ability to make unassisted "one-bell" landings (among many other
things, of course).
So far, maneuverability and lower wetted surface area for improvement
in light wind speed seems to be the consensus advantages for having a
spade rudder. I can understand why racers will want this ability for
rounding buoys without losing a second. I can also understand why
some weekend sailors might like this, if they are have trouble getting
in and out of their dock. All valid reasons in these applications, in
my opinion.
Could we move on to the other items in the list...I seriously would
like to hear the pros and cons of these items, please.
Deep, narrow, thin fin keel
Vertical foreward hull sections
Flat bottom hull
Wide, shallow aft hull sections
Low freeboard
Unbalanced or asymmetrical heeled waterlines
Shallow or non-existent bilge space
Swept-back spreaders
Carbonfiber mast needing 3 or more spreaders
5 or more batten pockets in the main
Battens in the head sails
Jim Manzari
Paul Kamen
Jim Manzari <man...@bluewin.ch> writes:
>...The Schumacher 40 (one of Paul Kamen's (fishmeal's)
>oft-recommended designers) and IMX-38, which are listed above as
>cruiser/racer and racer/cruiser (what's the difference?), seem to
>be prototypical of Prof. Larsson's "relatively low value from a
>safety point of view"...
Waitaminute, the Schumacher 40 is 123/3.8 and the J-42 is 133/8.6. These
are the two boats in your tabulation that come closest to the type of
ultralight cruiser that I advocate. If you claim that they have
insufficient capsize resistance, then I think you are on very shaky
ground.
Don't know anything about the IMX-38, but it's the only IMS boat
that doesn't look pretty good in your table, and it goes back to '92.
I keep re-reading your post, and fail to see how the data you present can
support your conclusions.
Jim Manzari
Here are two additions to the original consolidated list of LPOS
(vanishing point of stability) and POS/NEG ratio of stability curve
areas.
The two boats are Victoria 38 (Morris 38 in US) and Bowman 42. Both
medium fin keel with skeg rudders. Solid bluewater cruising boats.
[10] Data for these 2 additions taken from "Yachting World", January
1998.
LPOS POS/NEG
Design Year (deg) Stab. Ratio Remarks
-------------------- ---- ----- ------------ ----------------------------
J/N 1-Ton (IOR) 1984 111 2.0 frac IOR design
Block Island 40 1958 112 1.9* CCA design
Swan 391 SD 1987 112 2.2* Shoal-Draft
Nassau 45 198? 113 2.3 Bob Perry design
Grimalkin 1979 115 3.2 Fastnet disaster case study [1]
Dufour 30 Cl. 1997 115 2.9 Modern racer/cruiser [3]
Rhodes 37 1950 116 ?* full-keel w/ CB
IMX-38 (X-Yachts) 1992 116 2.4 IMS racer/cruiser
Cook 41 (IOR) 1984 117 2.6 MH IOR
Beneteua Oceanis 351 1994 118 3.1 Modern racer/cruiser [7]
Alden 43/45 1994 120 3.2* Modern shoal draft cruiser [8]
Schumacher 40 1994 123 3.8 IMS cruiser/racer
Tripp 36 1990 123 3.5 IMS racer/cruiser w/bulb keel
Rhodes Reliant 41 195? 123 ?
Frers 38 (Carroll M) 1989 124 4.0 Early IMS w/8+' keel
Navy 44 199? 129 6.7 Training Yacht [6]
Forgus 37 1998 130 21.0 Purpose-designed cruiser [9]
Bowman 42 1998 130 9.5 Purpose-designed cruiser [10]
J-42 1997 133 8.6 Purpose-designed cruiser [5]
Running Tide 1970 139 13.0 Built before IOR intro [2]
Westerly Ocean 33 1997 143 20.6 Purpose-designed cruiser [4]
Victoria/Morris 38 1998 145 32.0 Purpose-designed cruiser [10]
Contessa 32 1979 155 77.0 Fastnet survivor case study [1]
IR 12-meter 197? 180 n/m Inter. Rule 12-meter [2]
-------------------------------------------------------------------------
Jim Manzari
Lauri Tarkkonen
I think that it is better to try to create the directional stability
by desinging proper hull lines, than to rely on the skeg. In the case
of a near broach the spade rudder is much more helpfull than the rudder
and skeg combination. So a skipper who wants to minimize the possibility
of a steering disaster wants a boat with nice lines to give the hull
directional stability and in the case the sreering power is needed,
he will have a more efficient spade rudder to bail him out.
- Lauri Tarkkonen
Lauri Tarkkonen
In <352CD6E7...@bluewin.ch> Jim Manzari <man...@bluewin.ch>
writes:
>Lauri Tarkkonen wrote:
>>
>> If you have the idea that all structural and aero-hydrodynamical
>> aspects should be similar in airplanes and sailing boats, you
>> are a bit lost. What is good or necessary for airplanes is not
>> necessary good or necessary for sailing yachts. If this is your
>> argument for a skeg hung rudder, you must be joking.
>Am I missing something here? Have you never heard of NACA/NASA wing
>sections. I've seen them all over in boats yards for the past 25
>years. You might want to get a copy of "Theory of Wing Sections", Ira
>Abbot, Dover Publications, and browse the various <air> foil sections
>that are currently used in yacht design -- mightily bored you will be!
>No, I was not joking!
While reading that book did you pay any attention to the fact
that for different purposes different foil sections were recommended.
One factor was the speed and the other was laminar flow or no laminar
flow. Even if someone kindly collected a number of sections in the
same book, there was some advice how to choose proper sections for
different kind of use. Sailing some 2 to 20 knots in water is
placing different demands to the foils than fluying 100 to 200
and up to 1000 knots in air. I hope this fact did not escape
your curious mind.
>> After I modified my rudder so that I can turn it around I have
>> noticed that it is a veri usefull feature. Even if I only pull
>> the boat out from the dock with the buoyo line or the anchor rode
>> it is much easier to let the rudder rest in the reversed position.
>> When the foil is in the proper direction in regard to the movement
>> of the boat it steers the boat much more effectively.
>Very interesting, but not, I'm afraid, very high on the list of
>priorities for a bluewater cruiser (subject of this thread). Also, I
>can't think of a single cruiser that I met during my last 4 year
>voyage that had this feature. Only a very few boats had tillers and
>these were much too long to clear the backstay, if my memory serves.
I nvere said it would be high on your priorities, I just told you
about one usefull feature about the spade rudder if it is planned
to suit this. If your comment about the backstay was a genuine
concern about the usefullnes of the feature or if it was only
one way you try to annihilate my comment is something I can not
know. Judging about the tone of your post I do not think you
really are interested to know.
>> In manouverability the spade rudder that can be turned around wins
>> hands down.
>You might find it fun and satisfying to learn how to handle your
>boat in all conditions with any kind of rudder -- it's part of that
>accumulation of experience called seamanship.
My previous boats have all had skeg hung rudders so I am familiar
with them and know how to manouver them. Contrary to your belief
that you are the only one capable of docking a boat. I just tell
you that manouvering in reverse is much more effiecient with a
rudder that can be turned around.
>Good dockings are called "one-bell" landings by Navy and Coast
>Guard skippers and are the mark of a superb skipper. Military
>skippers pride themselves on their ability to make unassisted
>"one-bell" landings (among many other things, of course).
Of course to get extra points for the landing it must be done
with a boat that manouvers like a big, the other hand bound
behind your bäg and blindfolded.
>So far, maneuverability and lower wetted surface area for improvement
>in light wind speed seems to be the consensus advantages for having a
>spade rudder. I can understand why racers will want this ability for
>rounding buoys without losing a second. I can also understand why
>some weekend sailors might like this, if they are have trouble getting
>in and out of their dock. All valid reasons in these applications, in
>my opinion.
Of course true cruisers although they dock only once a year have
never met any difficulties in manouvering. Of course if someone
has ever had a problem, he is by your defintion not a member of
the fraternity.
>Could we move on to the other items in the list...I seriously would
>like to hear the pros and cons of these items, please.
Sorry, you have given me the proof you do not want to hear anything.
You just like to have an excuse to tell everybody how great you and
your wisdom and abilit is and how poor the rest of us are.
>Deep, narrow, thin fin keel
In most cases all extremes are doubtfull. You can have a moderate
fin keel.
>Vertical foreward hull sections
Moderate overhangs look nice and are usefull. Any extreme is even
here doubtfull.
>Flat bottom hull
I do not understand why you are interestd in a flat bottom hull,
but I am not sure that a very deep V-section is a holy solution
either.
>Wide, shallow aft hull sections
What you mean by wide. Most cruising boats have wide and flat
hull sections compared with our Scandinavian tradition.
>Low freeboard (extreme)
is as bad as extreme high freeboards.
>Unbalanced or asymmetrical heeled waterlines
If you do not accept asummetrical waterlines when heeled, you
must go the Ljunstrom school of boat design, there every cross-
cut section was elliptical and symmentric. Leaves you fery few
options though.
>Shallow or non-existent bilge space
is as useles as a three feet deep well that nobody can get clean.
>Swept-back spreaders
You do not know mucy about fractional rigs. They are actually
quite convenient allowing for self tacking jibs and much smaller
rig loads than masthead rigs and even better mainsail trimming
options. Of course true cruiser newer trim their sails, as it
might affect the performance of the boats and this is of course
a no no for true cruisers.
Swept back spreaders allow you to have a fractional rig without
running backstays in light to moderate air. You can then start
to use the runners after you reef your main.
>Carbonfiber mast needing 3 or more spreaders
I think many cruisers swear by carbon fibre unstayed mast.
>5 or more batten pockets in the main
Full lenght battens are very good even for a cruising mainsail.
>Battens in the head sails
I guess you have never had full lenght battens in your foresail.
They are very usefull.
You have any idea why the chinese developed their junk rig, using
full lenght battens. I know cruisers that swear by them.
- Lauri Tarkkonen
Anders Svensson
Jim Manzari <man...@bluewin.ch> skrev i inlägg
<352CD6E7...@bluewin.ch>...
> Could we move on to the other items in the list...I seriously would
> like to hear the pros and cons of these items, please.
I think your list is interesting. Just like you said in another post, your
questions have made me think deeper on these issues. Let me have a try at
it...
> Deep, narrow, thin fin keel
Is a shallow, thick full keel any better? Clearly, no - and I do not
suggest that you, Jim is proposing that. But where on the scale between
these extremes do you want to be. I would suggest: It depends - on the
rest of the boat and its configuration.
> Vertical foreward hull sections
Opposite: Horisontal forward sections - would you prefer flared sections,
rounded sections or what ? I may just as well confess that I do not
understand completely but I suspect that you mean flat bottom sections in
the foremost part of the hull. Or do you mean almost straight hull sides ?
> Flat bottom hull
Well two other 'opposites would be very deep hull or rounded hull. A flat
bottomed hull will give stability and a big waterplane area, wich reflects
load carrying capacity fairly well. A rounded hull will have less initial
(form-) stability, a very deep hull will be sensitive to load changes.
> Wide, shallow aft hull sections
Good downwind safety and extra reserve deplacement in the aft end.
> Low freeboard
Whats low, relative or absolute ? Low freeboard diminishes the wind
resistance and you may sail able to sail upwind (off a lee shore) in
heavier wind strenghts. The bigger the boat, the lower the relative
freeboard - absolute freeboard height may be governed by wish for standing
height (example).
> Unbalanced or asymmetrical heeled waterlines
Almost all small boats will get assymetrical heeled waterlines to some
degree. Long narrow boats will get less distorded lines, like some of those
sleek light cruisers.
> Shallow or non-existent bilge space
Hm... You must be thinking about boats with a keel bolted directly on the
hull. This is something I don't like either. I cannot find any benefit
with it... Wait! If the boat starts to leak, you will see it immediately -
yes - there's a reason for'ya... (Just joking)
> Swept-back spreaders
If you assume that all seagoing craft should have masthead rig, I'll
understand you. But if a big mainsail and relatively small (e.g not
masthead) headsails is considered a cruising virtue the simpler and more
easily set up rig with swept back spreaders instead of diamond stays may be
quite OK. With this setup you can also tune the rig easier to the wind
strenght.
> Carbonfiber mast needing 3 or more spreaders
Don't really understand this. Number of spreaders is basically a function
of boat width vs mast length, and with a narrow boat and a long mast you
may need 3 spreaders. It will cost you a lot of windage and weight aloft to
redesign the rig to be as strong with 1/3 as long unsupported columns.
Carbon spars are optional, ofcourse. Racing rules ban them, because they
are made of 'exotic material' - or at least that was the case some years
ago.
> 5 or more batten pockets in the main
I think this also is a function of how long unsupported leech you can (or
want) to have and as such dictated by the lenght of the mainsail in
relation to the material used. It is definetely adding to the lifelength of
the sail, the shape and the longevity.
> Battens in the head sails
This is also a longevity item. On narrow (blade) jibs, (IMO, a very useful
cruising sail) the aft leach starts to move (flap?) fairly quick (one hour
or so after taking delivery from the sailmaker) and a battened aft leech
will help tremendously in his respect. (There are even battens that are
formed like a steel measuring tape, and can be rolled on a furler).
So, even the most ugly storm cloud can have a silver lining...
BTW, witch boat *do* you prefer yourself. You have been telling a lot about
what's wrong with other peoples boats (or those proposed as cruisers) -
how about your ideal ?
Anders
Paul Kamen
Jim Manzari <man...@bluewin.ch> writes:
>Terry Schell wrote:
>>
>> vertical stab and rudder's primary purpose is to
>>provide static and dynamic stability not control.
>This looks like a good argument for a skeg and rudder
>combination on a cruising boat. Cruising skippers tend to
>like going in a straight line for thousands of miles while
>being pushed about by waves without wearing down the
>crew or burning out the autopilot.
Yes, if all that cruising boat ever do is go thousands of miles in
straight lines. However most offshore cruising boats are called upon to
maneuver a bit at each end of the voyage. (Oh, I forgot - *real* cruisers
always use their engines inside small anchorages and harbors.)
And this is news to me that autopilot loads are higher with a spade
rudder. Data or analysis, please?
>...Why don't you work out and tell us about the comparative
>level of forces experienced by both spade and skeg
>rudders while hove-to in a 45-knot gale....
The wind speed and wave height don't change the physics. Balance area
still subtracts from rudder torque when going astern.
Paul Kamen
Jim Manzari <man...@bluewin.ch> writes:
>I gather that you are giving a good reason for the lack of
>directional stability that frequently leads to a broach in so
>many spade rudder boats.
[sigh...] Back to directional stability 101.
A locked (or autopilot controlled) spade rudder is exactly equivalent to a
skeg/rudder combination of the same area as far as directional stability is
concerned.
>Sounds like a skipper who wants to minimize the possibility of
>a steering disaster in his cruising boat would want to follow
>the lead of aircraft design and make sure a skeg is part of
>the rudder assembly.
The skeg helps prevent broaching only if you're in the habit of letting go
of the tiller without locking it or engaging the autopilot first. If
that's what you do while sailing in broaching conditions, then you are
correct.
Jordan Bigel
Jim Manzari wrote:
>Slocum, nearly a hundred years ago, on the voyage lasting 72 days
>between Juan Ferdandez Island and Samoa went without touching the
>wheel for one whole month.
So he claimed. As has been noted here previously, he did exaggerate
freely with the intent of selling his story.
I'd bet he was exagerating when he said this.
J.
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
>Terry Schell wrote:
>>
>> vertical stab and rudder's primary purpose is to provide static and
>> dynamic stability not control.
>This looks like a good argument for a skeg and rudder combination on a
>cruising boat. Cruising skippers tend to like going in a straight
>line for thousands of miles while being pushed about by waves without
>wearing down the crew or burning out the autopilot.
You don't understand. The vert stab on an airplane is there to keep
the rear of the plane aligned with the local flow at all times. (or to
create massive drag under the conditions in which it is deliberately
misaligned with the flow) They are trying to achieve stablity around
AOA = 0. This is *not* the same as keeping the plane on a constant heading.
If you keep the stern of your boat aligned with the local flow
you *will* go in a straight line. Unfortunately, you will only be
able to go in a straight line directly downwind. It would be like
have a sailboat with truely *massive* lee-helm. The only way to get
the local flow at the rear of the boat to be aligned with the skeg is to
eliminate all side force on the boat... it would turn you downwind to
achieve that goal. Is this the "straight line for thousands of miles"
that you had in mind?
Repeat to yourself: The rudder on a plane functions like the
elevator/horizontal stab. in an airplane.
>> Once again, work through the forces. You will find the *moment* about
>> the axis of rotation is reduced (in both forward and reverse) as the
>> shaft is moved back from the leading edge of the foil (at least until
>> it is around 28% aft for forward motion and 72% aft for forces in
>> reverse). Only this moment is transfered to the helm.
>Sounds good theoretically. Why don't you work out and tell us about
>the comparative level of forces experienced by both spade and skeg
>rudders while hove-to in a 45-knot gale. Assume the boat is
>periodically thrown backwards on its rudder a distance equal to 1/10
>wave length, its full-load displacement is 30,000 pounds, significant
>wave is height of 30 feet, hove-to angle 50-degrees off the wind and
>sea. Then with your analysis in hand, bluewater skippers can select
>the rudder style that minimizes cost and maximizes reliability and
>maintainability.
I didn't offer to do boat design on the internet; I didn't claim that
spade rudders are uniformly better than skeg hung rudders. I just
posted a correction to your claims. You claimed that forces on the helm
of a balanced rudder were greater than an unbalanced one when the boat
is driven backward. This can be show to be false with a cursory inspection
of the engineering. Regardless of boat, the balanced rudder produces
less moment about the axis of rotation in forward and reverse. That does
*not* mean that it is a better rudder for a particular purpose... it just
means that your claim was 180 degrees out of phase with the truth.
Sincerely,
Terry
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
>Paul Kamen wrote:
>>
>> Probably because airplanes don't user their rudders to turn. The primary
>> function of the vertical fin is directional stability.
>I gather that you are giving a good reason for the lack of directional
>stability that frequently leads to a broach in so many spade rudder
>boats. Sounds like a skipper who wants to minimize the possibility of
>a steering disaster in his cruising boat would want to follow the lead
>of aircraft design and make sure a skeg is part of the rudder
>assembly.
You don't understand the difference between the different types of
stability. The Vert stab/rudder is there to always provide stabilty
about local AoA=0. The horizontal stab/elevator is there to provide
stability about a local AOA that is variable. For some conditions you
want that AOA to be +3 degrees for others -10 degrees.
The directional stability of a sailboat is analogous to the later.
You sometimes want leeway to port, sometimes leeway to starboard, but
once you have that angle set... you want it to return to it when the
boat's course is disturbed. If you want a leeway angle always equal
to zero, put a big vert fin on the back of your boat and she will
always turn downwind to insure no leeway.
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
>Lauri Tarkkonen wrote:
>>
>> If you have the idea that all structural and aero-hydrodynamical
>> aspects should be similar in airplanes and sailing boats, you
>> are a bit lost. What is good or necessary for airplanes is not
>> necessary good or necessary for sailing yachts. If this is your
>> argument for a skeg hung rudder, you must be joking.
>Am I missing something here? Have you never heard of NACA/NASA wing
>sections. I've seen them all over in boats yards for the past 25
>years. You might want to get a copy of "Theory of Wing Sections", Ira
>Abbot, Dover Publications, and browse the various <air> foil sections
>that are currently used in yacht design -- mightily bored you will be!
>No, I was not joking!
Note that Lauri said "you have the idea that all structural and
aero-hydrodynamic aspects should be similar". You cannot validate this
claim by pointing out that we often share one thing (foil sections).
You argued that since airplanes have "skegs" boats should have skegs.
This basically means you don't undersand why stabilty and control of
aircraft is fundamentally different that stabilty and control of
sailboats.
Sincerely,
Terry
Terry Schell
Jim Manzari <man...@bluewin.ch> writes:
>Here are two additions to the original consolidated list of LPOS
>(vanishing point of stability) and POS/NEG ratio of stability curve
>areas.
<snip>
Jim... can you please figure out the difference between the ratio
of pos to neg *areas* and the ratio of max pos to max neg RM ???
You mix the two numbers interchangable as it fits your purposes, in
spite of the fact that one number is approximately equal to the
*square* of the other.
kpk...@acpub.duke.edu
Now we're starting to see some REALLY interesting stuff!
> Lauri Tarkkonen wrote:
> > In manouverability the spade rudder that can be turned around wins
> > hands down.
>Jim Manzari wrote:
> You might find it fun and satisfying to learn how to handle your boat
> in all conditions with any kind of rudder --
Hmm- how many of you out there change the type of rudder on your boat
just to have fun learning how to handle it?
> ..... it's part of that
> accumulation of experience called seamanship. Good dockings are
> called "one-bell" landings by Navy and Coast Guard skippers and are
> the mark of a superb skipper. Military skippers pride themselves on
> their ability to make unassisted "one-bell" landings (among many other
> things, of course).
Funny, I never heard of this "one-bell" stuff. And you would need at
least two bells, "Reverse" (at whatever power deemed appropriate) and
then "Stop." It's usually also customary to ring up "Finished With
Engines" when you get a few docklines across...
> So far, maneuverability and lower wetted surface area for improvement
> in light wind speed seems to be the consensus advantages for having a
> spade rudder. I can understand why racers will want this ability for
> rounding buoys without losing a second. I can also understand why
> some weekend sailors might like this, if they are have trouble getting
> in and out of their dock. All valid reasons in these applications, in
> my opinion.
You forgot lower loads on the helm. See Anders' posts.
> Could we move on to the other items in the list...I seriously would
> like to hear the pros and cons of these items, please.
Well, I'm only going to repeat myself because you evidently didn't pay
attention last time.
> Deep, narrow, thin fin keel
More efficient going to windward.
Increases stability.
> Vertical foreward hull sections- no intrinsic benefit
> Flat bottom hull
Increased initial stability
Reduced draft.
> Wide, shallow aft hull sections
Increased reserve buoyany aft.
Improved off-wind steering.
> Low freeboard
Reduced windage.
Increased strength of hull.
Easier access to/from dinghy and/or docks.
> Unbalanced or asymmetrical heeled waterlines
Huh?? Every boat has this characteristic. Where do you think form
stability comes from?
> Shallow or non-existent bilge space
Increased headroom for given hull dimensions.
Reduced chance of unobserved flooding.
> Swept-back spreaders- no intrinsic benefit, however a marconi rig
could be designed to benefit from needing less standing rigging
by use of this feature.
> 5 or more batten pockets in the main
Reduced wear and increased efficiency of mainsail- better performance
when reefed particularly.
Greater longevity of sail.
-Note- these benefits are maximized with full-batten sails.
Fresh Breezes- Doug King
John S. Ward
Jim,
"There is no reason why any reasonable cruiser would ever want any of
these things." There, you got the answer you've been fishing for all
week. Feel better?
Jim, I don't think you'll ever convince the sailing community, no
matter how hard you try, that your way of cruising is the only
way of cruising, or even that it is the best way of cruising.
You sail the boats you love, the way you love to do it. Isn't
this one of the greatest attractions of sailing? Being the
captain of your own boat, doing things the way YOU like best,
not the way your boss or your landlord or your mother or your
local zoning board tell you you have to?
Jim Manzari wrote:
> Can anyone in this newsgroup explain what are the benefits to a
> bluewater cruising yacht, and its skipper and crew, to have any or all
> of the following features:
>
> Spade rudder
Without a skeg, the rudder can be balanced to reduce forces in the
tiller, making it easier for a light-weight sailor (especially the wife)
to drive, reducing crew fatigue, and reducing the forces needed by an
autopilot. Reduced wetted surface area will increase light-air
speed.
> Deep, narrow, thin fin keel
A deeper keel will in general have more righting moment
than a shallow keel. The fin keel will have less drag
than a bulb keel. It will have less surface area than
a full keel. The ruduced wetted surface will impove
light-air performance. The fin keel will provide better
lift, minimizing leeway and making dead reckoning easier
and more accurate.
A deeper keel needs less weight to provide a given righting
moment. Reducing weight has many advantages, such as
reducing needed sail area (and associated forces) and
reducing ground tackle weight.
> Low freeboard
Low freeboard reduces windage, and, by keeping weight low,
improves stability. You will point higher, sail faster, and
make less leeway when on the wind. Low freeboard is especially
helpful in heavy weather. When deeply reefed in a blow, I have
found that boats with high freeboard make huge leeway because
the area of the hull is comparable to the area of the sails.
Making progress to weather in these conditions is difficult.
In low freeboard boats, on the other hand, I have found that
it's easy to make progress to weather in high winds under
deeply reefed sails. This might be especially important if
your short-handed crew is trying to claw off of a rocky coast
in high winds. In fact, it could be a matter of life and
death.
The reduced weight above means higher stability. It also
implies that you need less ballast below. The reduction
in weight and windage implies lighter ground tackle. There
could be big advantages, both practical and safety-oriented,
in lighter ground tackle that the wife can raise without
the aid of her husband.
Reduction of windage leads to a reduction of leeway, improving
accuracy of dead reckoning, especially in heavy weather.
> Battens in the head sails
Battens in the headsail can improve the efficiency of the sail
and increase its lifespan.
Deep fin keels, spade rudders, and low freeboard can reduce
weight and improve performance. The side effect is that many
other pieces of boat equipment also become smaller, simpler,
and easier, ranging from smaller sails, to smaller winches,
to lighter ground tackle, to a smaller, more fuel efficient
engine, with, of course, less fuel. For many, this implies
faster, more fun passages, as well as reduced forces that
generally speaking make life easier for the short handed crew.
John S. Ward
Jim Manzari wrote:
> Sounds good theoretically. Why don't you work out and tell us about
> the comparative level of forces experienced by both spade and skeg
> rudders while hove-to in a 45-knot gale. Assume the boat is
> periodically thrown backwards on its rudder a distance equal to 1/10
> wave length, its full-load displacement is 30,000 pounds, significant
> wave is height of 30 feet, hove-to angle 50-degrees off the wind and
> sea. Then with your analysis in hand, bluewater skippers can select
> the rudder style that minimizes cost and maximizes reliability and
> maintainability.
The whole point of balancing rudders is that it reduces, not
increases, forces in the tiller.
If heaving to in a 45 knot gale in your 30,000# boat is such a
problem, how about trying a different tactic?
Iain Hibbert
Terry Schell <tsc...@s.psych.uiuc.edu> writes:
> You don't understand. The vert stab on an airplane is there to keep
> the rear of the plane aligned with the local flow at all times. (or to
> create massive drag under the conditions in which it is deliberately
> misaligned with the flow) They are trying to achieve stablity around
> AOA = 0. This is *not* the same as keeping the plane on a constant
> heading.
> If you keep the stern of your boat aligned with the local flow
> you *will* go in a straight line. Unfortunately, you will only be
> able to go in a straight line directly downwind.
Surely this is wrong? If a boat had a large fixed fin at the back in the
air, the tendency would be to round up into the wind. If a boat has a large
fin at the back in the water, the tendency would be to round up into the
current (or, only go forwards). Both tendencies could be defeated with
careful piloting at slow speeds (ie, you could go backwards)
I don't know about the rest of the argument.
iain
t.r.mcloughlin
Iain Hibbert wrote:
> Terry Schell <tsc...@s.psych.uiuc.edu> writes:
> > If you keep the stern of your boat aligned with the local flow
> > you *will* go in a straight line. Unfortunately, you will only be
> > able to go in a straight line directly downwind.
> Surely this is wrong? If a boat had a large fixed fin at the back in the
> air, the tendency would be to round up into the wind. If a boat has a large
> fin at the back in the water, the tendency would be to round up into the
> current (or, only go forwards). Both tendencies could be defeated with
> careful piloting at slow speeds (ie, you could go backwards)
Let me try: The flow over the fin in the stern of the boat
has two components: from ahead due to forward motion and
from leeward due to leeway. The forward component is always
aligned with the local flow (apparent wind/water flow), and
therefore imparts no tendency to turn the boat. The leeward
component tends to yaw the bow to leeward. The more the bow
turns to leeward, the greater the leeward component becomes
(more boat exposed to wind, more leeway), turning the boat
until DDW and the leeway component and the forward component
are parallel and in the same direction.
If you wanted the leeway of the boat to generate a weather
helm, it would have to be forward of the boat's center of
(what: gravity? effort?) whatever.
You are right if there is no leeway. Without leeway you
only have the forward aligning force. But add leeway
(which is present in all sailboats except heavy long-term,
family or couple bluewater cruisers) and you start to have
the lee helm tendency.
trm
Terry Schell
plu...@skate.demon.co.uk (Iain Hibbert) writes:
<snip>
>Surely this is wrong? If a boat had a large fixed fin at the back in the
>air, the tendency would be to round up into the wind.
Indeed. This is correct.
>If a boat has a large
>fin at the back in the water, the tendency would be to round up into the
>current (or, only go forwards). Both tendencies could be defeated with
>careful piloting at slow speeds (ie, you could go backwards)
Nope. If there is any lateral force at all from the sails. The
boat has some lateral motion through the water. A large fin in the
rear of the boat (large skeg for instance) will resist this leeway
trying to get the angle to zero. The front of the boat/plane lacks a
horizontal stab so it would get pushed further by the same lateral
force of the sails. This process leads, inevitably, to the boat
heading directly downwind regardless of how much forward force or
speed there may be.
In a plane you want that stabilty around zero AOA for the vert stab.
In a boat you would not.
PrestonMAP
I cannot fathom the reason for your questions. As I read your list I looked
for anything there that would be in anyway helpful to a bluewater cruiser, and
I didn't find it. You need a "bullet proof", uncomplicated, stable, heavy
cruiser that will protect you with the maximum degree of dryness and safety
that you can afford. You certainly don't need a deep fin, and spade rudder
catching on everything submerged, etc etc.
My frame of reference is 10 years of blue water cruising in a very heavy 38'
ketch that could balance and sail itself if needed. Seriously, Bill Crealock
designs have been such vessels for years. He's the architecht for the Tiburon,
my boat, the Cabo Rico, and others. I've raced before 20 ft. breaking seas for
three days and the bulkheads didn't even loosen. I'm alive and convinced.
Re. the 2 mo. of water needed,. get the manual water maker desalinator system.
Avoid anything electrical that could be manually done. Water conservation is
an art form. Food storage is also but there's lots written re. this.
Have fun. Marl Anne Preston
Steve Weingart
Let's put aside all of the aero/hydro dynamic stuff for a second...(I'll even
concede that fin keeled/spade ruddered boats potentially steer more
efficiently). OTOH balanced sail selection and trim often render this moot.
We are supposedly talking cruising boats here. We are talking about going far
away and making landfalls in strange places, where help might not be nearby...
So, I don't care how strong your spade rudder is, a keel hung rudder is likely
to be stronger. On top of that it is better protected, since the keel can sit
hard on the bottom with the rudder still hanging free. That ends the argument
for me.
I see too many so called cruising boats with the rudder hanging *LOWER* than
the keel (just go walking around boat yards...). Even if the rudder correctly
hangs a little higher than the keel, the bottom is not always flat.
Now maybe this is all because I do most of my sailing in FL, the Keys and the
Bahamas, but the bottom is always nearby, when you are not crossing something
to get where you are going (a small part of the time). The fact that my
rudder is likely to survive most encounters with the bottom is really
important to me (especailly when depths in the Keys make 12 ft on the sounder
feel like the Marianas Trench :-)
Just a thought...
(still sticking with a full keel with an attached rudder)
Steve (remove anti spam XYX in return address for correct email)
Lauri Tarkkonen
>Just a thought...
So far I can read, most of the discussion of rudders have been between
the suitability of skeg hung and spade rudders. If you do not call your
keel a skeg, this has nothing to do with the earlier rudder discussion.
Of course the keel hung rudder is better protected than a rudder with
divided lateral plan and to compare this to rudders that are deeper
than the keel is comparing oranges to elephants. I have earlier tried
to make a point that to compare a stupid and poor example of another
type to a reasonable and good example of another does not proove any-
thing. If you take a keel hung rudder that goes deeper than your keel,
though I have not seen any, they are as vulnerable as the spades and
skeg hung ones.
It is interesting than a (true) cruiser pays some attention to the
minor fact that he has to aproach the shore in the end of the cruise.
You take the safety aspect, I take the manouverability aspect. I have
seen many boats with keel hung rudders break them as they are not able
to turn or they let even the wind to press them to the side when they
manouver on reverse. To me it is better to be able to avoid the ground
than to build the boat so sturdy that I believe it will tolerate the
grounding. Prevention of the breagage is always the best way to go in
my book.
But what do I know, I have never crossed the Atlantic or the Pacific.
- Lauri Tarkkonen
Jim Manzari
Anders Svensson wrote:
>
> I think that te easiest way to convince you that this extremely simplifed
> evaluation model is simply not working by pointing out that the "best boat"
> according to these numbers will be a International 12 meter racing yacht.
Of course, a couple of numbers will not tell you much in absolute
terms. In relative terms, however, you must admit that there seems to
be a great difference between purpose-designed cruising boats and Joe
Ozelis' IMS examples.
It needs to be pointed out to you that Joe Ozelis (a dealer for Mumm
and Island Packet) (re-)raised this issue -- not me. At least he made
an effort to present us with some numbers that he believes are
correct, although I wished he had shown us the comparative numbers for
Island Packet types vs Mumm 30/36. Joe's efforts are a big
improvement over what most of the others who are pushing their racing
agenda in this newsgroup have done. They want us to believe they are
"experts" in all facets of cruising, marine engineering,
hydrodynamics, etc, yet they have nothing to offer with respect to
cruising. Very strange! I would think they would have data to refute
any argument at their finger tips. So far that has not been the case.
They have yet to make a meaningful contribution to this discussion.
So far all I've seen is wishful propaganda pushing racing designs for
bluewater cruising.
Any complaints regarding simplistic analysis should be taken it up
with those who have yet to present a single provable fact, or set of
comparative numbers, or meaningful personal cruising experience.
In the context of capsize (the subject of this thread), the 12-meter
is definitely the "best". However, as a bluewater cruising boat it
might leave something to be desired! :-).
As you probably know, but failed to point out, the area under the
positive and negative curves represents the amount of work required to
capsize or reverse the capsize respectively. The 12-meter requires no
work to bring it back upright. If one wanted a "self-righting"
lifeboat, for example, this is just this characteristic of area ratios
that you would want.
For long-term bluewater cruising, I think most experienced skippers
would agree, a boat with a high ratio of areas would be best. As in
all things, it would be a compromise and would probably require some
trade-offs with other characteristics of the boat. You will have to
admit there are many boats available with area ratios better than the
IMS average of about 3 and 122-degrees for angle of vanishing
stability. Unfortunately, in my view, the pernicious influence of
racing design is rapidly reducing the number of boats with good
bluewater cruising characteristics.
> What all this boils down to, is that with the right set of measurements,
> almost any boat can be proved a true cruiser. Correlation between some
> singled out measurements and cruising ability can easily be achieved, and
> this is one of the most common statistical traps to fall in.
Please note again that I did not raise this issue (see Joe Ozelis'
post). I am responding to the propaganda of some racing enthusiasts
in a newsgroup chartered to discuss cruising -- not racing. I would
much rather listen to a discussion of the relative merits of various
real bluewater cruising boats. Recommendations of ULDB, Santa Cruz
50, Merit 25, Express 27, Schumacher 40, etc. for long-term bluewater
cruising is flat wrong in my view.
Certainly a single number or two will not tell you much about a boat.
However, many numbers taken all together paint a pretty good picture
of a boat. Also comparing a set of numbers, as we have done here for
vanishing point of stability and ratio of positive and negative
stability curves, indicates very large differences between boats
designed specifically for racing and those designed specifically for
bluewater cruising.
> If I suggest that good cruising sailboats can be chosen by using fore stay
> diameter, rudder area, propeller axle diameter and pulpit tube thickness as
> criteria, I would possibly not go much wrong either. Throw in toilet seat
> diameter and the size and number of frying pans carried too - and it will
> be a sure-fire formula... :-)
Smily noted!
Might I suggest selecting a cruising sailboat on the basis of safety
criteria (disp-lwl around 275 or above, ballast ratio around 0.35 to
0.45, capsize risk less than 2, high angle of vanishing stability,
high ratio positive to negative stability, high lwl-beam ratio),
comfort criteria (comfort factor around low to middle 30s), and speed
criteria (Vmax). All these numbers taken ALL together, in maximum
proportion, should produce a pretty good boat from a standpoint of
safety, comfort, and speed.
Add to this your personal requirements of habitability, engine power,
water, fuel, and food requirements, rig type, anchor and mooring
arrangement, etc, etc.
> But I am quite sure Jim will find a good, strong and nice boat with
> his set of criteria - some of them even to my taste. But the
> operative word is taste, I think.
I keep having to repeat: safe, comfortable, and fast -- not speed by
itself!
Jim Manzari
Jim Manzari
Paul Kamen wrote:
>
> Waitaminute, the Schumacher 40 is 123/3.8 and the J-42 is 133/8.6. These
> are the two boats in your tabulation that come closest to the type of
> ultralight cruiser that I advocate. If you claim that they have
> insufficient capsize resistance, then I think you are on very shaky
> ground.
I have searched DejaNews to see if your name and J-42 can be
retrieved. Apparently you have never mentioned a J-42 or, as far as I
can find, any boat with a vanishing point of stability greater than
about 123 or an stability area ratio greater than 3.8.
Nice trick to try to combine the Schumacher 40 with the J-42. Given
that their respective resistance to turning "turtle" are 126%
different, why don't you give us all the numbers for both boats and we
can judge for ourselves.
> Yes, if all that cruising boat ever do is go thousands of miles in
> straight lines. However most offshore cruising boats are called upon to
> maneuver a bit at each end of the voyage. (Oh, I forgot - *real* cruisers
> always use their engines inside small anchorages and harbors.)
Again you are showing your ignorance of all things to do with
bluewater cruising. I would very much like to watch while you sail
into a strange Mediterranean harbor in August, at the height of the
crowded holiday season, drop your anchor, and moor stern-to the quai.
Remember if you ding someone, you might be there for a few days
sorting out the insurance headache with the owner and the port
capitan.
It would also be fun to watch you "sail" through a strange cut in the
reef into an atoll in the Pacific against the 5 knot current with
coral teeth on both sides.
Oh, and how many strange and dangerous river bars have you crossed
under sail only?
> And this is news to me that autopilot loads are higher with a spade
> rudder. Data or analysis, please?
My source for this assertion comes from Fishmeal's vanity Web site
account of the trouble he had with autopilots. I gather the problem
is that his Merit 25 doesn't track very well in reaching or running
conditions. It could, I suppose, have something to do with the racing
fin and spade rudder setup.
Jim Manzari
Jim Manzari
Terry Schell wrote:
> ...I think you must be making your "remarks" after looking at the
> LPOS since the J-42 is as much a "racer/cruiser" as the Oceanis.
Once again you are wrong! The characterization of racer,
cruiser/racer, or cruiser has been taken directly from each of the
references given in the original post. These characterization
(cruiser, cruiser/racer, etc.) are the reviewers or the copywriters,
not mine.
In the J-42 advert in Cruising World, you will note it does mention
racing only once and then only in reference to other boats ("...J-24
is rated faster in 'cruise-mode'...than others in 'race-mode'...").
The advert goes on to mention the word "cruise" numerous times. In
fact, it seems to pretty well focus on bluewater cruising by a husband
and wife couple:
"...thinking in terms of manageability by a cruising
couple...cruises upwind a 7+ knots...is rated faster for all around
speed...ranks first on an important indicator for
offshore sailors...length to beam ratio..."
This is not to say this boat couldn't be raced rather successfully,
but the emphasis by the designer is apparently on cruising. Most of
Johnstone's other designs seem to be flat-out racing machines. This
one is apparently not. It demonstrates that a safe, comfortable, and
fast bluewater boat can be designed. There may be other reasons why
this boat and others like it are not suitable for long-term bluewater
cruising, but capsize risk (the subject of this thread), comfort, and
speed are achievable in bluewater designs.
In my view, bluewater cruising boat design is a specialty and one
would be wise to look to designers who work in this specialized field
rather than those who specialize in racing. It won't do to simply
throw some flimsy furniture into a racing hull and reprint the sales
brochures to call it a "performance" cruiser -- something Johnstone
has clearly refrained from doing in the case of his J-42. This looks
like a boat designed from ground up to be a bluewater cruiser.
BTW, I don't endorse this or any other specific boat. I do, however,
like the honesty that JBoats shows in this advertisement. It is a
refreshing change from the usual hype.
Since you've raised the issue, let's look at the J-42 and the Oceanis
351 side-by-side:
% difference
J-42 Oceanis 351 rel. to J-42
--------- ----------- ------------
Disp-lwl 203.37 178.10
Ballast ratio 0.36 0.31
sa-disp 17.33 16.06
Vmax 8.69 8.09 -7.25% (worse)
cap-risk 1.74 2.11 21.26% (worse)
comfort 29.03 19.72 -32.07% (worse)
lwl-beam 3.40 2.49 -26.76% (worse)
FPOS 133.00 118.00 -11.28% (worse)
Area ratios 8.60 3.10 -63.95% (worse)
To be fair to the smaller Oceanis 351, we need to point out what you
should have known, Terry, a smaller boat will always be more prone to
capsize, less comfortable, and slower, all things considered, than a
larger boat.
> BTW... You are really screwing up the stability ratio. For some of
> these boats you are reporting the "ratio of areas" and for other you
> are reporting the "ratio of maximums". These are on very difference
> scales.
Don't you wish I were screwing up! No, Terry, once again you are
wrong. We do know the difference between area under the curve and
linear length of righting arm maximums. In order to insure fairly
good accuracy when we measured the areas under the curve, we ask two
of our colleagues to re-measure the areas. What you see is the
average of three area measurements.
Nice try at muddying the water.
> ...Especially when you get to label anything with high stability as a
> "purpose-designed cruiser" and re-label boats that are marketed as
> cruisers (Oceanis is the cruising version of the Bent. designs).
All the characterizations of type were taken from the review or
advertisement.
> You might choose to avoid a boat because of a 122 degree LPS.
> That is your choice. However, you should mention that the oceans
> (including the southern ocean) are safely sailed everyday by boats
> with an LPS of 122 or less.
Would you mind telling us where we can check this assertion in the
context of cruising NOT racing.
> ...For instance, I would take a boat with an LPS of 122 with a wx
> fax over a boat with an LPS of 150 without the weather info. I
> would rather sailing in a boat I find fun to sail, even if it means
> that I feel I should avoid hurricane areas. There are multiple ways
> to reduce risk to a level that is 'safe enough.' If you don't think
> so, then we should only drive tanks... or perhaps we should just
> stay at home where it is really safe.
Once again, Terry, you are showing your complete ignorance regarding
the details or nuances of bluewater cruising. You will find precious
little WFAX info available for the Indian Ocean, South Atlantic, or
Southeastern Pacific Ocean. And what bluewater skipper would depend
on a single critical piece of electronic equipment to keep them out of
trouble. Even if the equipment were 100% reliable, propagation
effects can block WFAX reception for hours or days. Very unrealistic
concept to rely totally on FWAX to stay out of trouble. It is a
useful aid (when it works), but nothing more, in my view.
Your strange theory which trades off fundamental seaworthiness for
dependence on an electronic gadget begs the question: How would you
have avoided the "bomb" storm of 1994 north of New Zealand. This
storm developed too quickly to show up on WFAX charts for many hours
after it had become a danger to the boats. Seven boats were lost, one
with all hands. The boat lost with all hands was a "performance"
cruiser.
These "bomb" storms, which are NOT cyclones or hurricanes, just
rapidly deepening depressions, occur several times a year in both the
northern and southern hemispheres. How, pray tell, would your
WFAX-equipped unseaworthy boat handle this survival situation? I can
see you having "fun" in your "safe enough" racing boat right to the
last minute before knockdown, capsize, and disaster.
Jim Manzari
Jim Manzari
Terry Schell wrote:
>
> ... can you please figure out the difference between the ratio
> of pos to neg *areas* and the ratio of max pos to max neg RM ???
> You mix the two numbers interchangable as it fits your purposes, in
> spite of the fact that one number is approximately equal to the
> *square* of the other.
Nice try at muddying the water.
Don't you wish I were screwing up! No, Terry, once again you are
wrong. We do know the difference between area under the curve and the
maximum value of righting moment. In order to insure fairly good
accuracy when we measured the areas under the curve, we ask two of our
colleagues to re-measure the areas. What you see is the average of
three area measurements.
If you have a problem with a particular number, would you like to tell
us which one and where you found alternative information for the boat
in question.
This is a good place to add two more boats to Joe Ozelis' list:
The two boats are the Sabre 402 and the Centurion 37S. Both appear to
be reviewed as cruiser/racers. Both have very short fin keels and
deep narrow spade rudders. The Centurion 37S seems to achieve its
stability by means of a narrow beam (11' 3'') vs (13' 4'') for the
Sabre 402. This is very similar to the technique used by Johnstone in
the J-42.
Reference source: [11] Yachting World, December 1997.
Design Year (deg) Stab. Ratio Remarks
-------------------- ---- ----- ------------ ----------------------------
J/N 1-Ton (IOR) 1984 111 2.0 frac IOR design
Block Island 40 1958 112 1.9* CCA design
Swan 391 SD 1987 112 2.2* Shoal-Draft
Nassau 45 198? 113 2.3 Bob Perry design
Grimalkin 1979 115 3.2 Fastnet disaster case study [1]
Dufour 30 Cl. 1997 115 2.9 Modern racer/cruiser [3]
Sabre 402 1997 115 3.0 Modern cruiser/racer [11]
Rhodes 37 1950 116 ?* full-keel w/ CB
IMX-38 (X-Yachts) 1992 116 2.4 IMS racer/cruiser
Cook 41 (IOR) 1984 117 2.6 MH IOR
Beneteua Oceanis 351 1994 118 3.1 Modern racer/cruiser [7]
Alden 43/45 1994 120 3.2* Modern shoal draft cruiser [8]
Schumacher 40 1994 123 3.8 IMS cruiser/racer
Tripp 36 1990 123 3.5 IMS racer/cruiser w/bulb keel
Rhodes Reliant 41 195? 123 ?
Frers 38 (Carroll M) 1989 124 4.0 Early IMS w/8+' keel
Navy 44 199? 129 6.7 Training Yacht [6]
Forgus 37 1998 130 21.0 Purpose-designed cruiser [9]
Bowman 42 1998 130 9.5 Purpose-designed cruiser [10]
J-42 1997 133 8.6 Purpose-designed cruiser [5]
Running Tide 1970 139 13.0 Built before IOR intro [2]
Westerly Ocean 33 1997 143 20.6 Purpose-designed cruiser [4]
Victoria/Morris 38 1998 145 32.0 Purpose-designed cruiser [10]
Centurion 37S 1997 150 27.4 Modern cruiser/racer [11]