Thread: Hydrofoil

The thing about those is that the effects are kind of difficult to predict. The main benefits are quicker jump onto pad and lower minimum planing speed.

The thing with the trim is that it takes more trim to run because of the fin, which makes your prop a little less efficient and that's where you lose speed or increase fuel consumption.

If your boat is fast, some bad things can happen because the extra lift ends up pushing the bow down into the water too much, and scary things can happen when turning if that happens.

Generally speaking, sometimes it could slow top end speed on boat that the hull, motor, prop, set up is in good shape.
BUT, they can work great and maybe increase top end on boats that are underpowered and/or stern heavy, wrong prop, water logged, etc.
If motor height is right and the foil is above the water line at WOT, top end speed wouldn't be affected very much.
Generally, a foil is considered a band-aid fix for another 'problem'. I have one on my boat (was on it when I bought it) and overall performance is better because of it. But, my boat is stern heavy and slightly underpowered (90hp and boat rated for 115hp), so I live with it rather than buying a bigger motor.