Most outboards and virtually all stern drives are NOT set up to use hydrofoils properly. What they don't tell you on the box or in the installation instructions is that in order to work as originally designed, any engine with a hydrofoil must be raised a minimum of 25mm above the normal 'X' dimension.
The way hydrofoils are designed to work is that they produce lift while in the water, getting the boat on plane at a lower speed, but once on the plane the last thing you need is a device producing more and more stern lift as you're getting faster. If you've ever experienced 'bow steering', you'll know how frightening that is at high speed. So with the drive/outboard up a few centimetres, the hydrofoil actually comes out of the water once it's done it's job (and thus no longer produces lift)... So, where's the hook? Outboards are dead easy to raise. Support engine, remove 4 nuts and bolts, lift engine, refit nuts and bolts, job done. Stern drives, not so easy. Remove drive, engine and transom plates. Glass up the hole (or weld in a new ali sheet). Cut new hole, refit transom plates, engine and drive...
Chris.....
