I/O Performance Advise

[bitsamonkey]

Hey Blue Heron, I think you got it backwards. A higher pitched prop turning lower rpm is more efficient than the other way around. OP, you're propped for a theoretical max speed of 54mph which you know won't happen. I remember towing my swamped seacraft with my big block powered inboard and the motor was able to "slip" the prop with no increase in speed. Maybe you should try a prop pitched closer to a realistic top speed and see what happens.