Can you be specific about make and model? In general, I wouldn't want anything smaller than an 80Hp 4-stroke Yamaha for planing. For displacement speeds I suppose you could get away with a 40.
Bolo - A lot depends on the hull that you are putting it on as Willy questioned. I don't think an 80 hp would come even close even if your boat is a light alumnium hull. Without knowing more my guess is 150-200 hp as a bare minimum.<br /><br />I have a 23' fiberglass CC with twin 110s and it is far from being overpowered. I would not want less on my boat.
Bolo<br />You want enough HP to get your boat on a good clean plane before you reach the best cursing RPM for the motor. If you have to go over the recommend crusing RPM to get on a good clean plane then it will cost you fuel mileage even if the engine is Smaller.<br /><br />Fiberglass I think 175 at least unless it is a deep V then I go with a 200.
