Re: prop ?
To determine the proper prop you need to know what the wide open throttle RPM is with an average load. The difference between what the engine manufacturer recommends for WOT rpm and what you actually observe is what determines whether you have the right prop or not and which direction to go (up or down) in pitch. Without that data we can only guess. The 11P you have is probably close but on that small boat you could probably use a 13P. 50 HP motors (same displacement as yours) typically run 13P props on 16 - 17 foot boats.
