Is Foil a brand or are foilboards a type of board? What makes them great? Thanks. - S
hydrofoil boards are where you ride on an airplane wing under the water. They are much better than planing on a board because the total wetted surface is about half that of a traditional planing board so you have a higher top end speed and lower friction at slow speeds. It also allows you to go upwind faster because the foil acts like a center board.
Hydrofoil development on kiteboards is basically at year 1 in terms of engineering and physics of the boards, everyone is racing on some version of the airchair hydrofoil which is highly unstable making it unsuitable for high winds.
If you look at the development of sailing and hydrofoils includes such boat as the international moth http://en.wikipedia.org/wiki/Moth_%28dinghy%29
the fastest sailboat in its class, with a front and back hydrofoil, it is still a bit unstable at high speeds, so it has a top end of about 35 knots.
Then there is the hydroptere, the fastest sailing vessel in the worldhttp://en.wikipedia.org/wiki/Hydropt%C3%A8re
max speed 52.86 knots
The foils on the hydroptere are well designed and very stable, however, this is such a big boat that at the top end, the hulls, masts and sails are all heavily stressed. It has capsized before in a gust, but I don't blame the hydrofoil for that.
I think it's really asking an awful lot of a kiteboarder to keep his weight constantly trimmed front back side, keep the kite in the proper direction and adjust his weight on an airchair hydrofoil. What is really needed is a proper dual foil board that has some negative feedback so it isn't so squirrelly, then you can race them in high winds, including the luderitz challenge.
Of course, if there is a lot of wind, there won't be a race because that will be a day for the real competition, so maybe the airchair foil design is good enough.
I love the foils, they are cool. People who use them, say it is sort of like a condom since you can't feel the water under your feet, so recreational kiters tend to go back to a regular board after trying out a foil board.