"I wonder if the curve would keep going in a straight line with a 3 horsepower input. : PGJ"

Theoretically, the curve would keep on going until the foils ventilated enough to kill the lift. For this type of foil, that happens up near the 40 knot region.

The small outboard would also work, Paul. You'd just need to resize the foils to create enough lift for the added weight in the boat. There are off-the-shelf foils available from Fastacraft out of Australia that could drop right into your proposed hotrod and you'd be out there terrorizing the neighbors.

Couple of things: The Flyak makes some use of the gyro effect of the spinning paddle mass to help stabilize the boat when flying. Tere is an inherent form of stabiity being generated from the horizontal foil surfaces themselves that rpovides the rest.

A motor powered craft would not get that benefit, so some means of stabilization would be necessary. The Foiling Moth sailboat uses crew placement out on trampoline wings to balance the boat. The Rave and Trifoiler make use of a third foil (one on each ama and one at the rudder) to achieve righting moment and stability.

There are other foil strategies that can be employed, so don't feel confined to the t-foil types that you have seen. Check out the photo below of the French boat, L'Hydrotere. The guys working on this project will be shooting for the 50 knot barrier this year off the coast of France.