Sailing Kayak Project

[sigurd]

It is hard to beat the simplicity of your rig in many ways. I came to think of this iteration of it. The assembly is mounted on the bow and has a wingsail and a fore aft symmetrical hinged j-foil. It could both jibe and tack, all the while actually shunting and flipping.

[sigurd]

you may have to join the proa_file yahoo group to access Biegler's paper. I can send it to your email if you wish.

[Tord]

Originally Posted by ancient kayaker

The twin foils with toe-in and asymmetrical NACA profile will outperform the single flat foil used previously and I think it will provide less leeway and drag than two symmetrical profile foils parallel to the centerline. It also keeps most of the lift on the lee side; the single foil worked better on the lee side. The foils will be hollow and sealed for extra bouyancy.

A single, bigger (thus longer), foil probably outperforms two smaller asymmetric foils,
unless you're are less capable in making symmetrical foils than asymmetric (which I
doubt). A bigger foil is less loaded, and if it is deeper (higher Aspect ratio), it has not much more drag than two smaller asymmetric ones.

And if you forget to flip up the windward foil the drag of that foil is a great problem, and n error that happens easily when tacking back and forth.

I too began with designing two asymmetric leeboards (with 9% thick foils), but switched to a single, approximately 12% thick, and I've been using that since! High AR, symmetric foils, outclasses twin foils any day!

The only improvement I can see is adding a flap to the single leeboard, thus creating
a asymmetric foil from a symmetric! This would have the added bonus of being more compact than two foils, and most likely better adjustable than twin foils!

Practical tests by real kayakers have shown that a single leeboard doesn't suffer much when used on the "wrong" side even if the theoretic lads thick otherwise :-)!

When I have studied videos on YouTube, OCSG, and elsewhere, I have never seen a double leeboard canoeist lift the windward foil!

A single leeboard makes life much easier :-)!

[ancient kayaker]

Tord: the windward foil cannot flip up but is (I hope) operating at zero lift/minimum drag.

Problem with a high AR foil is, it is long and has to be rigged further out to get the zero heeling effect that I am aiming for with this rig. I accept there will be inefficiencies with twin, non-vertical, low AR foils. Mainly I just want to try it out to see how it works.