Re: Do I need a new prop or a stabilizer fin?
If the prop is slipping due to ventilation, has the engine been mounted higher on the, I don't know if I would call it a transom, than the lowest position? Is it being over trimmed? Perhaps a prop with cupping would help.
All that said, the only real way to gain a 50% speed increase is to add horsepower.
Doel Fin, Whale tail, and other variations, to me, are a total waste and place a lot of stress on the engine. Trim tabs added to the hull are a different matter.
