I have a 1977 14 ft Alumacraft V hull fishing boat with a 9.9 Honda on it. Took it out for the first time I have had it in the water yesterday. The best I could get out of it was 10 mph with the wind at my back. I had a 14 ft lund that was basically the same boat with a 9.9 Evinrude on it that would do 18 mph. Is there that much power loss with a 4 stroke? It has a 9 1/2 x 8 5/8 prop on it and I just ordered a 9.25 x 9 hoping that that will help. I used the prop calculator to come up with that and I am wondering if I can gain a few mph or am I expecting to much? Thanks, Jim