Well....depends on what you want this thing for. If it's for the ultimate top speed you'll want traditional hydrofoils which are extremely thin to minimize drag, less than 5% depth of the foil vs. the foil's length.

If on the other hand you just want to have fun flying above the water, I've always thought that a bigger much thicker foil would work better, it would give actual floatation, floating part of the load of the boat, of course the drag would be much higher so the top speeds would be lower, but you'd still be above the water.

One of the tricks with foils is keeping the thing above the water while it's on the foils with the water ever changing in shape (waves), if the attitude changes you can crash back into the water very easily. There was a guy years back that came up with a mini water ski that controls one of the foils (sort of like the elevator on an airplane) to adjust the attitude to the water conditions, take a look at Hobie's Tri-foiler (sailing) for a good example.

Yep, I like these things too.

Bill H.