Optimal Sail Quivers
Janusz Mrozek
for the newer, wider-range sails?
For that matter, should sail sizes increase in constant proportion (as many
sail models do) or should they increase in fixed increments (as some do)?
Is there some connection to some law of physics? I remember from my days in
trucking that the air resistance of the truck increased with the square of
the speed, but I can't relate this rule to sail sizes (probably because sails
do not face the wind flat, but form a foil at a small angle of attack).
Why do I ask?
I sail on a mix of older Gaastra intermediate sails (as opposed to racing),
and my sizes go 4.5, 5.0, 5.7, 6.4, and 8.4. Aside from the big sail the gaps
increase proportionally at about 13 percent bigger than the next smaller.
I like Gaastra and I've been considering buying a quiver of CS II's, but
that sail line has the same sizes. I would like to be able to buy fewer sails,
but going every other sail in the line seems too much: 4.4, 5.7, 7.2. These
jumps are about 28 percent.
So why hasn't the benefit of wider wind range sails hit Gaastra's intermediate
sail lines? Is there another intermediate sail line (very loose definition:
not more than one internal camber or two external cambers) that allows me to
buy fewer sails?
Here is my optimal quiver. Until someone convinces me otherwise I assume that
sail sizes should increase in fixed proportion. As my base sail size I
arbitrarily choose a 7.5 so that I can get an IYRU sail for course racing.
After thinking about many combinations I have settled on 21% jumps in size,
which are larger jumps than in the sails I have now, but not as large as going
every other sail. The resulting quiver: 3.5 4.2 5.1 6.2 7.5 9.0 11.0
For my immediate needs here in the SFBay area I have a 3-sail quiver 4.2-6.2
instead of the 4-sail 4.5-6.4 quiver I have now. Give me some time and I'll
move up to 3.5 wind conditions eventually, but not yet.
I can approximate this quiver with Gaastra Slalomfoil Pro 4.2 5.2 6.2 but I
don't want the racing sails. Maybe I need to switch to Neil Pryde Street
Racer 4WD (?correct sail line, or is it the V8) 4.0 5.0 6.0 .
Anyway, I'd love to read what people think about sail ranges, proportionality,
ideal quivers, etc.
Janusz Mrozek
jan...@leland.stanford.edu
Payman Khalili
>
>For that matter, should sail sizes increase in constant proportion (as many
>sail models do) or should they increase in fixed increments (as some do)?
In my opinion, you should get the smaller size sails closer together
(i.e. smaller intervals) and the larger ones further. In high winds,
.3m^2 of sail makes a big difference.
It seems like you're sailing mostly in the Bay area. If I were you,
I'd just buy a really good sail in the 5.3 to 5.7 range since it seems
like 90% or more of the time that's the sail to use in the bay.
There's no point in really shelling out a lot for other sizes if you
never really use them that much.
So, instead of having 3 mediocre sails, you may prefer to get one top
of the line sail (which you use 90% of the time) and 4 cheapo sails
for the other days.
Essentially, by doing this, you're getting more sailing pleasure for
the dollar spent.
-Payman
Bo Farley
I have a 6.2 that I can hold onto pretty well even when people have rigged
down to their 4.5's. I also have a 5.2 that I sail when the 6.2 is overpowering.
I can sail these 2 gaastra in complete control in some very overpowering conditions just by adjusting the downhaul....
Richard Engelbrecht-Wiggans
>for the newer, wider-range sails?
>
>For that matter, should sail sizes increase in constant proportion (as many
>sail models do) or should they increase in fixed increments (as some do)?
>Is there some connection to some law of physics?
my 3.3, or up to my 4.5 on occasions. But, I would never dream of switching
from my 10.0 to a size only 0.5 or so bigger or smaller. (My next size
smaller is 8.5, and I have never felt there to be a gap in my sail sizes.)
So, at least in the extremes, constant steps seem not to make sense. Since
I believe physics at this level to be continuous, I suspect one wouldn't
want constant steps in the intermediate sizes either (although, for a small
number of sails, proportional steps and constant steps become hard to
distinguish.)
Now for some conjectures. Force is proportional to change in momentum
(physics). So, force on a sail depends on how much air is intercepted
by the sail (this depends on sail area), and how much the air's velocity
is changed (this depends on where in the sail the air hits, with the
greatest changes occuring near the mast.) This makes me guess that the
force on the sail (for a given wind, angle of attack, etc.) is propotional
to something between the first and second power of sail area. (For
similarly shaped sails, the area goes as the square of the mast length.)
Ok, now I am guessing that the amount of sail you can control depends on
the forces on it. Say you want to stay within a fixed percentage of some
maximum force. Then you want to choose sail sizes so that the xth power
of their size varies proportionally. If x=1, then vary sizes proportionally.
If x=2, then the sizes should vary by very nearly a constant increment
(For small y, (1+y)(1+y) = almost exactly 1 + 2y).
BTW. My sails go from 3.2 to 10.0 in roughly 15% jumps.
Roger Christal
>What do you think are the best size intervals for a sail quiver, especially
>for the newer, wider-range sails?
>
>Here is my optimal quiver...3.5 4.2 5.1 6.2 7.5 9.0 11.0
>
>For my immediate needs here in the SFBay area I have a 3-sail quiver 4.2-6.2
>instead of the 4-sail 4.5-6.4 quiver I have now.
My $0.02.
There is no doubt that the wind range of sails has increased
significantly with loose-leach, twisty sails.
iOn the other hand, board manufacturers and custom board builders have
focused on lighter and lighter boards for a variety of reasons. This
has significantly decreased the usable wind range of these boards.
Once on a plane and fully powered up, light and heavy doesn't really
matter that much. The top end speed of each will be very close.
You mention a SFBay quiver of 4.2, 5.1 and 6.2. This is great IF you
have the boards to support the quiver.
As an example, what happens when you're sailing the 6.2 and the wind
picks up, but not quite enough to rig down to the 5.1? You really
want to be able to go to a smaller board so that you don't get totally
blown away. The problem is, this smaller board also has to support a
wide range of sailing conditions; ie, fully powered 4.2. That is
quite a wide range of conditions, isn't it?
Of course, you eventually want to get into 3.5 conditions, right?
Well, will that smaller board support those conditions also, or are
you going to need a third board?
The point is, you should try to have the optimal equipment for the
current conditions. I feel this means having a quiver of sails spaced
by about 0.4 sqm apart in small sails, 0.5 sqm apart in the medium
range and 0.6 sqm in the larger sails.
Think about a day on SFBay when it is blowing a perfect 5.5. Which
sail are you going to rig? The 6.2? What if the wind picks up
significantly? Or, how about the 5.1? Are you willing do to the hula
for a few hours? What happens if the wind dies? In either case, how
far offshore are you willing to go when you know the sail you rigged
isn't really right for the conditions?
My quiver is 6 sails from 3.5 to 6.2. With this quiver, I don't have
to sail totally overpowered and I don't hula.
--
>>=- Roger Christal rog...@techbook.com rog...@ssd.intel.com -=<<
K.H.GOODRICH@.larc.nasa.gov
Christal) writes:
>
>The point is, you should try to have the optimal equipment for the
>current conditions. I feel this means having a quiver of sails spaced
>by about 0.4 sqm apart in small sails, 0.5 sqm apart in the medium
>range and 0.6 sqm in the larger sails.
>
>Think about a day on SFBay when it is blowing a perfect 5.5. Which
>sail are you going to rig? The 6.2? What if the wind picks up
>significantly? Or, how about the 5.1? Are you willing do to the hula
>for a few hours? What happens if the wind dies? In either case, how
>far offshore are you willing to go when you know the sail you rigged
>isn't really right for the conditions?
>
>My quiver is 6 sails from 3.5 to 6.2. With this quiver, I don't have
>to sail totally overpowered and I don't hula.
>
>--
>
>>>=- Roger Christal rog...@techbook.com rog...@ssd.intel.com -=<<
>
wind is always gusting and its going up and down. The point being that know
matter how many sails you've got in your quirver, you're going to hula some,
and you're going to slog some. So rather than rack my brain trying to decide
which of a half dozen + sails to use, I carry a 6.0, 5.0 and 4.2 -- that more
then satisfies my needs as a high-performance recreational salior.
Jim Munro x2497
4.2 Waddel Surf Slalom (single camber convertible)
4.7 NP Wave RAF
5.0 NorthWave Trilite XL (single camber convertible)
5.5 NP Surf Slalom (Two Camber Converible)
Personally I think my quiver sucks, mainly because I buy about one sail per year.
If I could start again, I'd probably get something like the following:
3.5 Wave
4.0 Wave
4.5 Single Camber Wave Slalom (mono)
5.0 Single Camber Wave Slalom (mono)
5.5 Slalom/Race fully cambered
6.0 Ditto
I know it makes sense to increase each sail size by a percentage rather than by
a fixed amount. However, I feel I am more sensitive in the 5.0- 6.0 range
and can tell the difference between a half meter ior so. When it's really
raging, I'm always overpowered and wouldn't be able to pick the right sail if
thay were too close together. Make sense?.... it does to me.
Jim Munro
Jim Munro x2497
single cam surf/slalom sail? I forgot to ask.
Jim Munro
Juri Munkki
2% Infinity 3.6 (1989) I use it without the camber
5% Infinity 4.3 (1990) 1 camber (optional, but I use it) x 1.19
8% Infinity 5.0 (1991) 1 camber (optional, but I use it) x 1.16
75% Gamma 5.5 (1991) 3 cambers, same as Prisma, but no monofilm x 1.10
10% Gamma 6.5 (1991) 3 cambers, same as Prisma, but no monofilm x 1.18
I wouldn't make any changes even if I could start over again. The percentages
are estimates of how often I used each of the sails this summer. (I have
exact statistics, but this is just a rough estimate.) If I had to manage with
just 4 sails, I would replace the 3.6/4.3/5.0 subquiver with a 3.9 and 4.6.
In the last column, the 4.3 is 1.19 times bigger than the 3.6 and so on.
This summer has been abnormal...usually I would expect to use the 6.5 as
much as the 5.5. We had an excellent summer up until two weeks ago, when
the weather changed...there has only been maybe 4 windy days in September
so far.
I weigh 65 kg and for each 10 kg more, I suggest adding 6% to the sail sizes.
--
Juri Munkki Windsurf: fast sailing
jmu...@hut.fi Macintosh: fast software
Kirk Lindstrom
>>For that matter, should sail sizes increase in constant proportion (as many
>>sail models do) or should they increase in fixed increments (as some do)?
>
>I'd just buy a really good sail in the 5.3 to 5.7 range since it seems
>like 90% or more of the time that's the sail to use in the bay.
>There's no point in really shelling out a lot for other sizes if you
>never really use them that much.
>
>So, instead of having 3 mediocre sails, you may prefer to get one top
>of the line sail (which you use 90% of the time) and 4 cheapo sails
>for the other days.
>
>Essentially, by doing this, you're getting more sailing pleasure for
>the dollar spent.
>
>-Payman
Hmmmm. I sort of agree with Payman, except that I'd get two used RACE sails.
I had a Gaastra Speed Slalom and Upgraded to a Gaastra/Rushwind Gorge Slalom
LE (1991, monofilm, tube battens, etc.) and there was no comparison in
top end or low end performance. For learning to jibe, I once removed
one of the camber inducers (It is a convertable sail) and it was ALOT
easier to flip the sail, but not as fast. For me, a 5.7 and a 5.0 race
sail would get me on the water for a few hours most days I sail.
I like the good race sails as they seem to have a good, wide range (but then
I haven't sailed the other sails ). I am not an expert but have sailed
Race sails for quite some time.
Kirk (BTW, my 5.7 is for sale if interested - $275/b.o.) out
Will Howard
sail is used.
It would also be useful to post what board is being used with each sail. Also
for wind conditions if possible say what the winds are in terms of knots or
Beaufort number of meters/second, but not in terms of sail size, since this
will vary according to sailor's weight, board size, wave conditions, sail
design, point of sail, and other factors besides wind speed itself.
Simon Tait
This is my sail/board quiver, which has evolved to a state which I'm pretty
happy with.
sea sailing, mostly Portland harbour, Weymouth
% sailing sail size battens board comment
30% 6.5 5 3.65m 175l non-planing
35% 6.5 5 2.77m 98l planing
20% 5.7 5 " " " "
10% 5.2 5 " " " "
5% 4.2 4 " " " "
lake sailing, mostly Cotswold water park
% sailing sail size battens board comment
50% 6.5 5 3.65m 175l non-planing
35% 6.5 5 2.95m 125l planing on and off
10% 5.7 5 2.77m 98l planing mostly
5% 5.2 5 2.77m 98l " "
1% 4.2 4 2.77m 98l " "
I spend most money on the larger sail sizes (paticularly the 6.5!) and
these are also closely spaced because this is where most of my sailing
happens and its nice to get the right size.
My 4.2 is a load of crap, and every time I have to use it I vow to get
a better one.. But when it comes down to it, there really is little point.
My wife and I share equipment. She weighs 126lb and I weigh 154lb.
This works well for sails, since we are one sail size apart over the range.
I used to own a 7.5, but found it too big and heavy to be fun, particularly
when the wind is variable. My wife finds a 6.5 too heavy.
Our sailing is "recreational" and so we tend to buy rotational 5 batten
non-induced sails.
Hope this is of interest..
Simon Tait
Bath, England
Kirk Lindstrom
>4.0 Wave
>4.5 Single Camber Wave Slalom (mono)
>5.0 Single Camber Wave Slalom (mono)
>5.5 Slalom/Race fully cambered
>6.0 Ditto
>
>I know it makes sense to increase each sail size by a percentage rather than by
>a fixed amount. However, I feel I am more sensitive in the 5.0- 6.0 range
>and can tell the difference between a half meter ior so. When it's really
>raging, I'm always overpowered and wouldn't be able to pick the right sail if
>thay were too close together. Make sense?.... it does to me.
>
>Jim Munro
Hmmmmm. Not really. With the newer Race and Slalom sails, you have MUCH
more range. For your list, I'd replace the 5.5 and 6.0 with a 5.7 and a
6.4. It is too bad that many sail companies want our money so bad that
they only offer sails in 0.5 meter increments above 5.0.
My quiver:
Main Back-up/for sale
3.9 Gaastra Wave Slalom (removable half and full battens)
4.5 Rushwind GS LE (2 CIs - one tube batten for the gusts)
5.1 Sailworks Race (mono on order) 5.1 Rushwind GS LE & 5.0 Gaastra Racefoil
5.6 SW Race (mono) 5.7 RW GS LE (mono)
6.1 SW Race (mono)
6.7 SW Race (mono)
7.5 North TCC (old) (don't use much so I'd sell for a good offer)
If I were to do it again, I'd get a 3.7 and a 4.1 rather than the 3.9, but I
got a good deal on the 3.9 and didn't feel like spending alot of $ for 2 sails
I'd hardly use..
The only good thing about having 0.5 meter increments, is I can rig for
the conditions and then go down a full meter once I'm too powered to sail
in control. With 0.7 meter increments, going down 1.4 meters is more
difficult and one sail size may not last long enough if the wind is
building. When sailing the 5.6 or 5.7 when the wind builds, I switch
boards from my 8'11" to my 8'8" then rig my 4.5 when and if it is still
too much power.
Also, my Rushwinds are convertable so I guess I could use them for
waves though I'd not try this with the 5.7 since it is monofilm.
Kirk out
8'8" Challange Flex, 8'11" & 9'3" ASD epoxy, 9'9" Velocity & 11'6" Malibu
Wt 213#, Ht. 6'0", Usually sail on SF Bay, Cailf. (ki...@hpocia.sj.hp.com)
Kirk Lindstrom
conditions" one can be.
>Regarding: From: ki...@hpcc01.corp.hp.com (Kirk Lindstrom)
>
>> I like the good race sails as they seem to have a good, wide range (but then
>> I haven't sailed the other sails ). I am not an expert but have sailed
>> Race sails for quite some time.
>
>So I'm confused. I thought that race sails have a narrower, not a wider,
>wind range than intermediate sails, and that's why one needs more of them. Am
>I just wrong?
>
I believe that intermediate sails are easier to handle and allow one to have
fun while keeping bad habits. I've sailed my 3 Cam 5.6 Sailworks Race sail
in 4.5 conditions while I couldn't do anything but plow with a friend's
5.0 single cam intermediate sail. After the experiment, I rigged my 4.5
race sail and went out and had alot more fun. I think one can get away with
1 meter increments with good race sails and alot of pumping ability PLUS
good rigging knowledge.
Having 0.5 meter increments allows you to more closely rig for the
conditions.
Kirk
Tom Albertz
> ... that they just want to make more bucks? When the trade show hits
> San Francisco in October, I will ask them directly.
You may not find the people you're looking for at the trade show.
Neosport is the Tiga/Neil Pryde distributor and they will be there
to display the 1993 line. Whether Neil and his designers will be
there is questionable. I don't believe they have been in the past.
Maybe Bjorn will be there!!!
> Regarding: From: ki...@hpcc01.corp.hp.com (Kirk Lindstrom)
> > I like the good race sails as they seem to have a good, wide range ...
>
> So I'm confused. I thought that race sails have a narrower, not a wider,
> wind range than intermediate sails, and that's why one needs more of them. Am
> I just wrong?
I'm afraid you are wrong. Race sails handle a wider wind range than
rec sails. They hold their shape better; don't deform in the gusts,
etc.
> I don't really agree. I sail my current board (Mike's Lab 120l 9'3")
> from 8.4 to 5.0 conditions (I'm 145 lbs). I tried it once at 4.5,...
I once sailed a 9'-0", 115 l. board in 4.3 conditions and hurt
myself bad enough that I won't do that again. I pearled the nose
(I guess that comes from pearl diving...) and was catapulted onto
the rig. My shoulder hit the mast hard. Now the Tiga 260 comes
out when the 4.6 comes out. I know you said you can't afford a
shorter board, but can you afford a broken shoulder?
> Say I get a 4.5 and a 5.5 (22% bigger). Do I need a sail in between?
No. Get an 8'-6" board first.
tom.
Ken Poulton
> wind range than intermediate sails, and that's why one needs more of them. Am
> I just wrong?
Yes you are wrong. Race sails generally hold their shape longer
over a wider wind range. In my view, the only reasons *not* to use
race sails are cost, durability, or maneuverability (i.e., wave
sailing). I find them *easier* to use than lower-cost sails.
> I don't really agree. I sail my current board (Mike's Lab 120l 9'3")
> from 8.4 to 5.0 conditions (I'm 145 lbs). I tried it once at 4.5,...
I sailed my 9'0, 112 liter CFX in 4.0 conditions a couple of days
and in 3.5 conditions one day at the Gorge this year. The board was
a little big for that, but not unmanageable. I just went to a 10"
wave fin and sailed in areas with small swell (~3 feet). This board
performs nicely under sails up to 6.2; I use 13.5" and 14.5" blades
for less wind. At first I was appalled at the prospect of
needing a fin quiver as well as a sail quiver, but it's cheaper
(and easier to carry) than a deep board quiver.
> Say I get a 4.5 and a 5.5 (22% bigger). Do I need a sail in between?
Depends on how good your sails are (how wide their ranges are) and
your rigging technique. When my race sails get real hard to handle,
I figure I can go down 1 meter (2 sizes) in sail size. I still
have sails at 0.5 m increments because it lets me hit the wind
range I need with just one sail more often.
Ken Poulton
pou...@hpl-opus.hpl.hp.com
Dan Driscoll
>>(Janusz Mrozek) writes:
>>>(Kirk Lindstrom) writes:
>>>I like the good race sails as they seem to have a good, wide range ...
>>So I'm confused. I thought that race sails have a narrower, not a wider,
>>wind range than intermediate sails, and that's why one needs more of them.
>>Am I just wrong?
>I'm afraid you are wrong. Race sails handle a wider wind range than
>rec sails. They hold their shape better; don't deform in the gusts,
>etc.
"Race sails handle a wider range than rec sails"?
Okay, I'm getting confused. I thought the latest design in sails was the
flat pre-twisted leech which is supposed to spill excess wind in gusts.
Are these these the designs referred to as "intermediate"?
Do the pure "race" sails have more rigid shape up top, which prevents escape
of wind during gusts?
If so, then how do they end up being faster? I thought it was recently
discovered that lots of shape up high resulted in more wind friction which
caused a low top end in regards to speed.
Please excuse these questions if they seem naive. I'm trying to understand my
new Northwave PRX sails compared to my old Trilites and Slaloms. I'm not very
familiar with Northwave's top of the line RX sails other than they have more
cambers to deal with and use lighter material. Is it that stiffer rigid-foil
sails remain faster, regardless of all the shape, but are harder to control
in gusty conditions?
So if this shapely race design is more powerful, how can they handle a wider
range? It seems the sails that spill gusts would be more suited for a wider
range because they're easier to control, but would result in lower speed.
Maybe what you actually mean is
"Race sailors can handle a wider rage than rec sailors"
because race sailors are used to the rigors of controlling rigid-foil race
sails?
-dan
(doing more musing than sailing, unfortunately)
Kirk Lindstrom
>>> I haven't sailed the other sails ). I am not an expert but have sailed
>>> Race sails for quite some time.
>>
>>wind range than intermediate sails, and that's why one needs more of them. Am
>>I just wrong?
>>
>fun while keeping bad habits. I've sailed my 3 Cam 5.6 Sailworks Race sail
>in 4.5 conditions while I couldn't do anything but plow with a friend's
>5.0 single cam intermediate sail. After the experiment, I rigged my 4.5
>race sail and went out and had alot more fun. I think one can get away with
>1 meter increments with good race sails and alot of pumping ability PLUS
>good rigging knowledge.
Just another example. I sailed Sat. (first time in 11.5 weeks) and let my
friend with the intermediate 1990 5.0 sail try my 1989 Rushwind 5.1 with the
tube battens. It was too light for his old 5.0, but he was ripping around
and making lots of jibes with his 8'8" ASD board and my sail. I, on my
8'11" ASD with a 6.1 SW Race, used to be much faster. That day I had to do
all I could to stay ahead. Needless to say he bought the sail.
Kirk out
Roger Christal
>"Race sails handle a wider range than rec sails"?
This is a pretty technical issue that is really hard to explain
properly, especially since I am not a sail designer. If you are
interested, go to your local shop and pick up Issue 3, 1992 of
Performance Windsurf Report. It contains an interview with Sailworks
designer Bruce Peterson who discusses in some detail how these sails
work. It's good reading.
If you can't locate a copy of the interview, I'll contact the magazine
and see about reprinting portions of the intervierw here. Let me
know.
Chad Price
PLease reprint. The nearest dealer with a store and magazines from here is
either Kansas City (3.5 hrs drive) or Denver (8 hrs.)
thanks
Ken Poulton
> "Race sailors can handle a wider rage than rec sailors"
> because race sailors are used to the rigors of controlling rigid-foil race
> sails?
Not at all. I'm only intermediate, but I immediately found that
race sails are *easier* to control in gusty/overpowered conditions.
Race sails have lots of cambers and a rigid design generally to hold the
shape of the draft and keep the center of effort from moving back in the
sail in a gust. I don't think they really spill wind because once the
sail is powered and the mast bends sideways (downwind), the floppy
leach is no longer floppy. The result is that instead of a gust
deforming the sail, moving the draft back and pulling the boom away from
your back hand, it mostly just gives you more power. At least, it does
better at this than the lower-end sails.
Ken Poulton
pou...@hpl-opus.hpl.hp.com
Kirk Lindstrom
(Kirk Lindstrom) writes:
>>>I like the good race sails as they seem to have a good, wide range ...
(Janusz Mrozek) writes:
>>So I'm confused. I thought that race sails have a narrower, not a wider,
>>wind range than intermediate sails, and that's why one needs more of them.
>>Am I just wrong?
(Tom Albertz) writes:
>I'm afraid you are wrong. Race sails handle a wider wind range than
>rec sails. They hold their shape better; don't deform in the gusts,
>etc.
}"Race sails handle a wider range than rec sails"?
}
}Okay, I'm getting confused. I thought the latest design in sails was the
}flat pre-twisted leech which is supposed to spill excess wind in gusts.
}Are these these the designs referred to as "intermediate"?
}Do the pure "race" sails have more rigid shape up top, which prevents escape
}of wind during gusts?
}If so, then how do they end up being faster? I thought it was recently
}discovered that lots of shape up high resulted in more wind friction which
}caused a low top end in regards to speed.
}
There is a several page interview in "Gorge Performance Review" (or some
such mag with a name close to that which I got in the mail this week) with
Bruce Peterson of Sailworks. He answers many of these questions fairly well.
In a few words, most of the R&D money goes into Race sail development. For
that reason, Sailworks (SW) only has 3 lines of sails (race, wave and CAM 1
(+1)). This way, BP feels that SW can service their customers better instead
of having a huge selection of sails (such as the 3 biggies) where most of
the nonrace and nonwave sails are more marketing than anything else.
Anyway, my experience with the newer race sails says that when fully powered
and a gust hits, I accelerate PERIOD. My modified '89 Rushwinds (GS LEs which
were race sails in '89) handle much like the "intermediate" sails of today
in that they handle gusts well, but don't have the tremendous acceleration
that my SWs have. BP went on to say that the 4.6 SW Race was DESIGNED to
be sailed from 20 to 40 knots. The way the sails handle gusts are different
for every size (at least for SWs) but they generally open up at the top
to "exhaust the wind" while moving the CE a bit forward and lower which
accounts for the added control (this was new to me and explained alot). I
believe my modified RWs just keep the draft in the same location (more or
less) and exhaust the wind like the newer sails. BP goes on to say that he
designs each sail around a certain mast and uses different battens for
every sail to get the desired shape and gust handling characteristics (one
reason I've never liked North Sails since they seem difficult to select
the correct mast though once the right mast combination is found they work
quite well).
Well, that was more than a few words. Check your local shop for the mag.
if you want more info.
}Please excuse these questions if they seem naive. I'm trying to understand my
}
Great questions, this is what this forum is for!
}So if this shapely race design is more powerful, how can they handle a wider
}range? It seems the sails that spill gusts would be more suited for a wider
Better design - more R&D money spent on them to do it right rather than
marketing money to get one to buy "intermediate sails" that you will
later want to upgrade if you get REALLY INTO windsurfing.
}range because they're easier to control, but would result in lower speed.
}
}Maybe what you actually mean is
}
}"Race sailors can handle a wider rage than rec sailors"
}
True, but I've taken the advice of buy used race sails rather than new
"intermediate sails" since I bought a new IM sail and later sold it to
get a used race sail when I discovered the difference. Well, actually,
I buy new race sails since I sail so often it is worth the money to me.
This was 2 years ago when I was just a beginning shortboarder. Rec
sailors will also benefit from good equipment. One friend was
light-years ahead of me 2 yrs ago. He said I was so fast on the
learning curve since I bought good equipment. He is still better, but
at least we can sail and jibe in the waves together at 3rd Ave.
}-dan
}(doing more musing than sailing, unfortunately)
}----------
}
Gerard Horan
>> Maybe what you actually mean is
>> "Race sailors can handle a wider rage than rec sailors"
>> because race sailors are used to the rigors of controlling rigid-foil race
>> sails?
>
>Not at all. I'm only intermediate, but I immediately found that
>race sails are *easier* to control in gusty/overpowered conditions.
>
>Race sails have lots of cambers and a rigid design generally to hold the
>shape of the draft and keep the center of effort from moving back in the
>sail in a gust. I don't think they really spill wind because once the
>sail is powered and the mast bends sideways (downwind), the floppy
>leach is no longer floppy. The result is that instead of a gust
can look up and see the sail twist off. The twist is very noticable
and therefore the WIND must be spilled. I have heard of Speed Sails
which have many many cambers ( 8 or so ) that have a very narrow
wind range and are extremely rigid. Are these the sails we are
talking about here that do not spill wind?
>
>Ken Poulton
>pou...@hpl-opus.hpl.hp.com
gerard
Tom Albertz
> can look up and see the sail twist off. The twist is very noticable
> and therefore the WIND must be spilled.
When a gust hits, the sails probably do spill a little air. The main
thing about twist, tho, is that the sail is taking a more efficient
alignment with the apparent wind. This translates to speed. The air
is moving faster 12 feet above the water than at 3 feet.
tom.
k...@onan.jhuapl.edu
writes:
If anyone is interested, I did a sample calculation of the desirable (optimal)
twist based upon Marcaj's analysis of true wind veer and induced drag veer. If
memory serves, optimal twist for a generic 7.5 was about 15 degrees. BTW,
dinghy sailors (generally) believe that overtwisting a sail will ensure that at
least part (horizontal section) of the sail is working well... For example, in
gusty conditions it is unlikely that you can keep the sail at the proper angle
of attack all the time, and thus an overtwisted sail will have a portion that
is not either stalled or at less than the proper angle of attack.
On another note, I got to take a close look at a '92 North 7.2 Prisma and
compare it to my '90 7.5 North Prisma. I can see how the range of the '92
probably exceeds the range of the '90. I can also see that the bottom end of
the '90 is much better than the '92. Probably have to use the '92 in
significantly more wind. This is born out by the comparitive performance of the
two sails in that days racing.
Kim
Kirk Lindstrom
>> can look up and see the sail twist off. The twist is very noticable
>> and therefore the WIND must be spilled.
>
>When a gust hits, the sails probably do spill a little air. The main
>thing about twist, tho, is that the sail is taking a more efficient
>alignment with the apparent wind. This translates to speed. The air
>is moving faster 12 feet above the water than at 3 feet.
>
>tom.
At the trade show, I discussed this with Bruce Peterson. He referred to
the effect as "exhausting wind". It is both spilling wind AND working
more efficiently much as the headers in my Fiat x1/9 help the engine
create more power. As Tom says, the improved efficiency allows the
sail to accelerate the sailor rather than just load-up her arms OR go
along at the same speed as if the gust haden't occured (i.e. what would
happen if the sail just spilled wind).
Kirk (trying not to break wind!) out