Sorry,

But the wings are an AC keel are not intended to function of an aircraft
winglet. The function of the aircraft application has been effectively
described here, the the wings on a keel have a primary function that is
different. The tip vortices are pretty much confounded buy the huge
bulb (much like an aircraft tip tank will do).

The wings are actually designed to provide additional lift to windward
that is not dependent on the keel blade attack angle.

That is why they pay so much attention to the attack angle of the wings
during the set up and trials. They have to play out a dual between more
angle for more lift to weather when heeled and less angle for less drag
with the boat upright going to leeward.

As the current IACC rules have not allowed this to be trimed underway,
they only get to set it once per race, and if you listen to the
discussions going on the background, you will here them talk about the
adjustment as three-quarters or one-half degree.

Matt Colie (certifications available on request)

Nav wrote:



Oz wrote:

On Mon, 02 Feb 2004 11:27:49 +1300, Nav
scribbled thusly:



DSK wrote:


Navvie wrote:



From: http://www.djaerotech.com/dj_askjd/d.../wingfin1.html



This is from a model airplane web site, and some of the terminology for
hydrodynamics is rather different. For one thing, we don't talk
about the
"helix angle" of underwater foils. For another, attempting to get a net
forward (or windward) lift component from keel winglets isn't going
to work
because they have to sail on both tacks.



Yep, that's why they are on both sides.

Cheers



Which chucks you whole spiel out the window.
Ever see a jet with winglets that extend to the lower side of the
wing?



Never flown inverted on a 747-400 no. Come to that I've never flown on
any inverted jet, but if they were flying both sides up with equal
frequency you can bet there would be winglets on top and bottom... It
really isn't all about the end plate effect you know. Look at AC
winglets -its all about controlling the parasitic drag from the keel tip.

OK?

Cheers