Hello, I have Cygnus cygnett 23 that weighs 3.5t fully loaded. I have a Honda bf150 outboard, I had prop that was 14.75 x 15 on it was only doing 11knts at 4500RPM. A Honda dealer recommended I stick a 15.5 x 13 and now this has improved but not by much its doing 14.5knts at 5100RPM.
Can anyone...