Originally Posted by JoaAmb
I found a picture and I have a 9.75 inch, 11 inch pitch, 3 blade propeller with model name 48 896896a40 11p.
Max speed: 27 knots, 6000 rpm 1 person (2 not tested)
75 % rpm = 25 knots
Boat levels out at 9-10 knots
Very quick acceleration.
Boat weight approx 110 kg. Engine 71 kg. My weight 70 kg.
How are you measuring revs?
I'd be surprised if you can get much more out of it, 27 knots in a 3.6m boat sounds about as fast most people would want anyway.
An 11" prop at 6000 rpm (with a 1.92:1 gearbox) would give a theoretical maximum speed of 28.3 knots. You'd expect 10% slip, so you are doing well. At 75% revs it should be impossible to go more than 21.2 knots, so either your RPM or speed doesn't add up.