l ' H Y D R O P T E R E

[rapscallion]

Would a 20' scale model of l ' H Y D R O P T E R E perform better than the rave?

[Doug Lord]

Thats a good question. Numerous small boats have been built using surface piercing foils like Hydroptere and fully submerged foils like the Rave and the Hobie Trifoiler. The Rave and Trifoiler used different kinds of altitude control systems and, of course, surface piercing foils don't need
altitude control systems though Tom Speer has recently suggested that they might benefit from one.
The Rave is an excellent design but because it is rotomolded and aluminum it is heavy. It does, however, actually sail in winds too light to foil and foils in 10-to 12 knots.It has retractable foils so that it is beach sailable and even has two foiling settings for max draft and shallow draft. Because of its weight and foil system it is draggy in light to moderate wind but as the wind picks up- with foils generating all the righting moment- it has high top end speed. As I said in my PM Brett Burvill was the first person to win a race on foils in the Moth class and he used surface piercing foils for the two main foils. They were ruled illegal("multihull configuration") in the Moth class but fairly recently he told me that he thought that given the same intense development seen in the bi-foil system the surface piercing system would probably be competitive both upwind and downwind.
See the book:"Icarus-the boat that flies" for some good early examples of both surface piercing foilers and fully submerged foilers.
My personal opinion is that Kotaro Horiuchi may be on the right track with a bi-foil system on a small trimaran. One less foil and the ability to use "Veal Heel" are some of the benefits.