Re: sailing axis vs lat resistance axis?

i have an idea that lee boards can have their support box built onto
themselves instead of onto the hull. in other words a carpeted piece
of 2x4" on the back of the lee board to fit against the hull wherever
it works best and adjustable fore and aft. adjustable toe in. bill

http://www.hci.net/~shamblin/sboat.htm


--- Inbolger@yahoogroups.com, "Peter Lenihan" <ellengaest@b...>
wrote:
> --- Inbolger@yahoogroups.com, "pvanderwaart" <pvanderw@o...> wrote:
> >
> > That said, you are correct that there are limits to how well a
> simple
> > shape can be kept in balance and most flat-bottomed boats sail
> better
> > in an upright attitude.
> >
> > I quite agree with your chain of thought as it applies to folks
> > wondering about putting 1 degree of toe-in on their leeboards.
> >
> > Peter
>
> That is one of the interesting things about some of our
> Heros"boxes".With the Micro and her kin,Bolger attempts to match
the
> curve in plan view with that of the rocker.As these boats heel,they
> present a nice symetrical"V" shape to the water and appear to
remain
> perfectly balanced.At greater angles of heel, I've often felt that
it
> was the immersed chine that was doing most of the lateral
resistance
> work while the ballast keel was just doing the lever-arm task of
> keeping me comfy in the boat without trapizes.
> It's a fascinating area of study and the multitude of dynamic
forces
> at work some times leaves me wondering how we ever got a boat to
> sail"up-wind" in the first place :-)
> Bolger once wrote a caution about being tempted too quickly toward
> the toe-in as a fix since,apparently,it can be all too easily over
> done and will work against you in the right(wrong?) conditions.
>
> Peter Lenihan
--- Inbolger@yahoogroups.com, "pvanderwaart" <pvanderw@o...> wrote:
>
> That said, you are correct that there are limits to how well a
simple
> shape can be kept in balance and most flat-bottomed boats sail
better
> in an upright attitude.
>
> I quite agree with your chain of thought as it applies to folks
> wondering about putting 1 degree of toe-in on their leeboards.
>
> Peter

That is one of the interesting things about some of our
Heros"boxes".With the Micro and her kin,Bolger attempts to match the
curve in plan view with that of the rocker.As these boats heel,they
present a nice symetrical"V" shape to the water and appear to remain
perfectly balanced.At greater angles of heel, I've often felt that it
was the immersed chine that was doing most of the lateral resistance
work while the ballast keel was just doing the lever-arm task of
keeping me comfy in the boat without trapizes.
It's a fascinating area of study and the multitude of dynamic forces
at work some times leaves me wondering how we ever got a boat to
sail"up-wind" in the first place :-)
Bolger once wrote a caution about being tempted too quickly toward
the toe-in as a fix since,apparently,it can be all too easily over
done and will work against you in the right(wrong?) conditions.

Peter Lenihan
> when a pointed bow/square stern boat sails heeled over the sailing
> axis of the hull is not parallel to the keel. how can it work
> to have a centerboard or lee board that does have an axis
> parallel to the keel in that case.

Bill,

This is a complicated area. Certainly when you consider the
unsymmetric shape of any boat when heeled, there is no reason to
think that the direction parallel to the keel is the least resistance
direction of travel. If fact, the definition of "direction parallel
to the keel" may lose precision.

However, the assumption in the first sentence quoted above is
probably not justified. In a well designed boat, the 'middle' in the
fore and aft sense is closer to the stern than to the bow. Thus the
wider part of the stern is also shorter, and the buoyancy due to
immersion of the stern quarter when heeled should about balance the
buoyancy of the heeled bow, at least within limits. Designers work
out the buoyancy of the immersed sections in heeled conditions to
make sure that it is so, and they are well aware that boats dont's
sail well in 'bow down' attitudes.

That said, you are correct that there are limits to how well a simple
shape can be kept in balance and most flat-bottomed boats sail better
in an upright attitude.

I quite agree with your chain of thought as it applies to folks
wondering about putting 1 degree of toe-in on their leeboards.

Peter
>when a pointed bow/square stern boat sails heeled over the sailing
>axis of the hull is not parallel to the keel. how can it work to have
>a centerboard or lee board that does have an axis parallel to the
>keel in that case. my ignorance is a vast swamp

It just does. Aren't boats wonderful? <chuckle>
--
Craig O'Donnell
Sinepuxent Ancestors & Boats
<http://freepages.genealogy.rootsweb.com/~fassitt/>
The Proa FAQ <http://boat-links.com/proafaq.html>
The Cheap Pages <http://www2.friend.ly.net/~dadadata/>
Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
American Proas, the Bolger Boat Honor Roll,
Plywood Boats, Bamboo Rafts, &c.
_________________________________

-- Professor of Boatology -- Junkomologist
-- Macintosh kinda guy
Friend of Wanda the Wonder Cat, 1991-1997.
_________________________________
---
[This E-mail scanned for viruses by friend.ly.net.]
when a pointed bow/square stern boat sails heeled over the sailing
axis of the hull is not parallel to the keel. how can it work to have
a centerboard or lee board that does have an axis parallel to the
keel in that case. my ignorance is a vast swamp

my last bolgeresque boat was a scow with parallel sides and a lee
board to match.



bill shamblin