Gybing Daggerboard?

Gybing Board on a non-heeling Multihull

Most of these discussions where concerned with heeling monohulls.

I would ask of the potential benefits for a non-heeling multihull to make use of a gybing board?

Perhaps this gybing board might be a single board located under the bridgedeck of a cruising catamaran. :?:
http://www.boatdesign.net/forums/multihulls/bridgedeck-centreboard-why-dont-they-work-57051-7.html#post796712

 

I think the contribution to leeway prevention from the hulls is greater on a cat. The hulls are deeper compared to their beam and there are 2 of them. A cat seems to sail upwind better than a mono with its boards up. Therefore a gybing board needs to work harder on a cat to take up the work from the hulls contribution to leeway prevention.

Asymmetrical boards would be better IMO. Tspeer gave a good technical answer as to why. How many gliders have symmetrical airfoils? Zero. Because a symmetrical foil at a higher angle of attack gives a much worse lift to drag ratio compared to a correctly selected asymmetrical section.

 

I tend to agree with you Dennis,...and I think the implement of the asymmetric boards (twins as on my design) would be easier.
http://www.boatdesign.net/forums/multihulls/bridgedeck-centreboard-why-dont-they-work-57051-4.html#post795051

 

I think for a cruising design like yours a single board would be better. I would only see asymmetric boards sensible in a high performance craft. Its just not worth the hassle, cost in installation, weight and extra effort in operation where the boards need to be changed over each tack for a cruiser. But I do think your idea is a clever innovation.

 

Initially the asymmetry came about as a result of wanting a flat side on the board to lay against the flat nacelle plate. But then I thought I might gain some extra performance by the asymmetry,...and I would have a 'back-up' board in case one was damaged on a long voyage. And it didn't appear as though it was going to be that much more involved to provide the two,..that was my thinking.

Per my posting on that other subject thread, I figure the 'development' boards could be fabricated from good plywood. In fact I think you could get two asymmetric boards cut out of one 4'x 8' std size sheet of plywood perhaps glued up double thickness