Expert: Paul Soderman - 7/19/2009

Question
i have a 26' powerboat if i could design them would sponsons attached to the sides provide some lift and perhaps tighter turning radius.like a jetski?

Answer
Kent
I believe you are describing hydrofoils, which are small airfoils (hydrofoils) that lift the boat if you develop enough speed to raise the hull.  Because they provide much less surface area than the hull, they have less drag so the boat can get more speed.  But that doesn't help your turn radius.  Some race boats actually have a fin sticking down to help the turn.  Jet skis turn sharp because they are light and the rider leans the boat hard so the lift vector has a component in the turn direction.  A snow skier does the same thing.  You can do the same thing with your boat but the lean angle is small and your momentum is large.

Incidentally, some hydrofoils are designed to ride under water but must be constantly adjusted for angle of attack as conditions change.  Other hydrofoils are designed to ride on the surface, but you get a choppy ride.  Do a google search on hydrofoils.
Paul