Leeboard vs. Centerboard?
A Auerbach
leeboards versus centerboards for small sailboats?
I understand the advantage of hanging the board off
a gunwale, but am perplexed by how the damn things
can work when you are tacking -- half of the time it
would be mostly out of the water. A dumb question,
I know.
Alex
Dave Carnell
of single pivoting leeboards, the ideal for small boats.
Dave Carnell <http://home.att.net/~DaveCarnell>
Classic Boatworks of Maine
You need 2 leeboards, one on either side. No dumb question except the one
that isn't asked!
--
Good Luck and Fair Seas
Marshall and Jo Duhaime,Jr.
Classic Boatworks of Maine - We build and restore classic wood boats.
http://www.nemaine.com/classicboatworks
A Auerbach <auer...@aapr.com> wrote in article
<QDC92.25233$aF1....@typhoon-sf.snfc21.pbi.net>...
Bill Denes
>
>--
>>
>>
Michael Neverdosky
windwardboard. :-))
The advantage of leeboards is that they can be set at
different angles to reduce leeway and the attachment
can me much simpler.
The advantage of a single board is (usually) less weight
and fewer parts.
BTW I used to sail (as well as row and power) my 10'
Portaboat (foldup plastic) and it used a single aluminum
board bolted to one side. Worked fine.
michael
Al Gunther
> Good Morning Alex,
> You need 2 leeboards, one on either side. No dumb question except the one
> that isn't asked!
For larger vessels this is true. However, many small boats (up to 12 feet
at least) in fact do sail with one board, switching it to the lee side on
each tack. These are simple rigs, only a lanyard on a weighted board and a
bearing cleat on each side of the hull set to the right angle.
--
Al Gunther, Kingston, WA <---- 47° 52.7'N, 122° 30.9'W
Paul Kamen
>Can anyone point me to some dummy-level info about
>leeboards versus centerboards for small sailboats?...
Two other options worth considering, especially if don't mind an
unconventional configuration:
1) Bow and stern rudders, but no centerboard or leeboard. Both bow and
stern rudders need to be active so the hull doesn't have to go sideways
when it turns.
2) Set up the rig way aft, so that the side force balances over the
rudder, and no centerboard or leeboard is required. Works fine for fast
sailboards with only skegs for side force. Some external strakes or
shallow longituncal keel might be needed to help with turns.
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Al Gunther
> 2) Set up the rig way aft, so that the side force balances over the
> rudder, and no centerboard or leeboard is required. Works fine for fast
> sailboards with only skegs for side force. Some external strakes or
> shallow longituncal keel might be needed to help with turns.
So could something like say an El Toro be set up that way? That sounds
interesting. A mainsailless yawl. I presume a balanced rudder would be
desireable?
There is an interesting book entitled "Clean Sweet Wind" which is worth
reading for many reasons, one being the detailed descriptions of the
numerous fast, weatherly small sailing craft of the Caribbean. They all
had low aspect sails with just skeg and many sailed with only an oar for a
rudder. They also had a fine enrty on the bow, so were steered much by
shifting weight fore and aft I expect.
Migchelsen
Migchelsen
half is placed on starboard, the starboard half is placed on the portside .
Both convex sides. are against the boat sides. For optimum performance they
must have camber, caster, and toe-in. Toe-in is maximum with the board
vertical down. decreasing to zero at 45 deg.
The max. toe-in varies between 2 to 4 degrees. Not much, but it is the same
minimal amount as the frontweels of your car. Caster is optained by making the
hinge hole slightly of the longitudinal center axis. The (neg.) camber is
optained by mounting the boards on a tumbled home strake build above the
guardrail. The Dutch word Boeier, pronounced BOOIER, means a build up extra
strake. Compare to the word build. L-boards were not invented by the Dutch.
They saw them in China on there early discovery trips, late 1400, early 1500.
There are two types.For green water a fat pear shape,. For blue water slim,
long board. The Duth made the outside slightly concave. They looked like an
aircraft wing. This gave (slightly) extra lift. Easy to explain with todays
knowledge of aerodynamics. The remarkable thing is that they did that 300 years
before anybody started to know a little bit about aerodynamics. I have always
wondered why in North America where practically every teenager knows about the
front end of cars and aerodynamics is such a familiar subject, leeboard
principles are seldom properly understood. Hope this longwinded explanation is
of help. For small boats you don't have to make the hollow on the outside.
leave it straight. Cheers. Barend
Paul Kamen
>...I have always wondered why in North America where
>practically every teenager knows about the front end of cars
>and aerodynamics is such a familiar subject...
Excuse me while I wipe the coffee off my monitor!
North Americans are profoundly ignorant of aerodynamics. Not only because
math is so poorly taught here, but because of the counter-intuitive and
erroneous models used to explain aerodynamic pricnciples (a partial list
appears in one of jnewborg's recent posts, and in my response).
One common misconception, for example, is the relative importance of
section shape versus planform. Aspect ratio and spanwise lift distribution
will almost always control efficiency more than section shape. And even
Abbott and Von Doenhoff, in the standard reference on foil sections, begin
with a warning to this effect. So before we get excited about asymmetrical
leeboard sections we should probably think about aspect ratio and induced
drag from root and tip effects.
Leo Voorneveld
Regards Leo
For Open 6m50 Class ( Mini Transat)
surf to; http://www.xs4all.nl/~blvrd
Wayne Saewyc
haven't been mentioned:
1. Leeboards are effective for 100% of their submerged surface area,
and gain efficiency with toe-in, as opposed to centerboards only
effective for the portion of their surface area below the aperature
(usually less than 50% of the centerboard). For this reason they're
usually smaller, lighter, require less ballast, etc.
2. 2 leeboards and their associated tackle usually weigh less than a
centerboard and trunk.
3. No hole in the hull to develop leaks, or board to get jammed in the
slot.
4. Hull scantlings can be reduced (because there's no hole in the
centerline.)
Now the bad points:
1. Leeboards must be tacked. When short boarding, you can leave both
down and just deal with the racket or... on one design I saw a rigging
arrangement where the board downhaul was spliced into the opposite board
uphaul, so one string handled both operations. I have no idea how this
would work in practice; you might need to use a winch or put it on a
lever.
2. Depending on the design and your personal aesthetics, leeboards
often look a bit clumsy (he said politely.) A few designs look
particularly nice, rather like a duck with its wings folded, but there
are more that look like an origami barn.
Chris Crandall
: 1. Leeboards must be tacked. When short boarding, you can leave both
: down and just deal with the racket or
Although I can agree with everything else in this post, I must disagree
here.
(1) You can leave both boards down, and there's no racket. Occasionally,
the windward board will "broken wing" away from the hull, but not all the
time. Depending upon your tackle, the board mya be stiff, held in place,
or free-and-easy.
On the Bolger Black Skimmer that I sailed out of Key Largo, when I sailed
with both boards down, the windward board stood out a bit from the hull,
and never "crashed" into the boat once, in failry windy and wavy
conditions.
(2) A single leeboard, fixed on a single side, is a workable proposition
on small boats. I built a Bolger Teal, which is a leg-o-mutton rigged
sharpie, with a single leeboard on the port side (held down with a bungee
cord). It works fine on both tacks, was *easy* to build, makes no
appreaciable noise, and pops up easily, when need be (those helpful
bungees).
On a significant cruiser, things would be different, I suppose. If you've
ever seen the Herreshoff "Meadowlark", you know that leeboard boat can be
beautiful. Of course, a trip to Holland would also persuade you.
Mike Goodwin
>ever seen the Herreshoff "Meadowlark", you know that leeboard boat can be
>beautiful. Of course, a trip to Holland would also persuade you.
>
never throw the 'meadowlark' in with that crowd.
IMHO it is the ugliest boat L. Francis H. ever tried to design . It looks
better on paper than in person .
Dave Carnell
Piscataqua River gundalow. They used a heavy iron bar outboard of the board
and running fore and aft below the board's pivot point and above the
waterline.
Chris Crandall wrote:
> Wayne Saewyc (wsa...@means.net) wrote:
> : 1. Leeboards must be tacked. When short boarding, you can leave both
> : down and just deal with the racket or
>
> Although I can agree with everything else in this post, I must disagree
> here.
>
> (1) You can leave both boards down, and there's no racket. Occasionally,
> the windward board will "broken wing" away from the hull, but not all the
> time. Depending upon your tackle, the board mya be stiff, held in place,
> or free-and-easy.
>
> On the Bolger Black Skimmer that I sailed out of Key Largo, when I sailed
> with both boards down, the windward board stood out a bit from the hull,
> and never "crashed" into the boat once, in failry windy and wavy
> conditions.
>
> (2) A single leeboard, fixed on a single side, is a workable proposition
> on small boats. I built a Bolger Teal, which is a leg-o-mutton rigged
> sharpie, with a single leeboard on the port side (held down with a bungee
> cord). It works fine on both tacks, was *easy* to build, makes no
> appreaciable noise, and pops up easily, when need be (those helpful
> bungees).
>
Jacques
>A Auerbach wrote:
>> I understand the advantage of hanging the board off
>> a gunwale, but am perplexed by how the damn things
>> can work when you are tacking -- half of the time it
>> would be mostly out of the water. A dumb question,
>> I know.
>>
Just as Migchelsen and Leo Voorneveld, I come from a country where
leeboarders are very common. I sailed quite frequently onboard (Belgium and
Holland) of these large boiers, lemmeraaks etc. and can guarantee you that
these leeboards are not easy to use or simple to build.
Later, I worked with the Bureau Trismus when JP Brouns designed a 65' ocean
going leeboarder: same conclusions.
Good leeboards are difficult to build and design, they are only efficient
when asymetrical in shape and alignement and remember, at each tack you
should lift one, drop the other. If you don't the drag may stop you. They
also don't always like to go down: be ready to push. If you run aground with
them, they are not as well supported as a CB and will break.
Why would anybody go through all the troubles of building and using two
boards instead of one?
The only good reason to have leeboards is to get rid of a CB trunk in the
middle of a cabin but even then, it's not worth it.
--
replies to:
Boat Plans Online
http://www.bateau.com
Migchelsen
LBRTY4US
In article <19981208221752...@ng-cb1.aol.com>, migch...@aol.com
(Migchelsen) writes:
>You do not know your leeboard construction from a hole in the ground, Barend
Well, go ahead and teach us what you feel works best.
Migchelsen
What I can do is send you the complete text with drawings, no charge to explain
it to you. Send in that case a pp, preadressed envelope to B. Migchelsen, 1515
Hamilton Place, Dorval, Que, H9S 1H3.
LBRTY4US
In article <19981210193147...@ng11.aol.com>, migch...@aol.com
(Migchelsen) writes:
Sorry to have missed it & that I'm presently without access to DejaNews -
didn't mean to ask you to repeat yourself - thank you for your offer via the
mail, I'll do it.
Mark Anderson
> fish...@netcom.com (Paul Kamen) wrote:
>
> > 2) Set up the rig way aft, so that the side force balances over the
> > rudder, and no centerboard or leeboard is required.
> So could something like say an El Toro be set up that way? That sounds
> interesting. A mainsailless yawl. I presume a balanced rudder would be
> desireable?
About 20 years ago there was a large rudder with sail atop the
rudderhead that was on the market for a "sail outboard". I think I saw
it in one of Donald Street's "Ocean Sailing Yacht" books. I don't know
whatever became of it. It looked odd, but reportedly worked. I think
there's a similar rig somewhere in Bolger's books.
--
Mark Anderson
Riparia
"The trouble with good ideas, is that they soon turn into
alot of hard work." Anon.