it is a 40hp... I had the same problem a while back...was told to rehub the prop... did that and took the boat out. It ran fine until i stopped. When I put it in gear again, it wouldn't go at full throttle. The engine sounds as if it is running fine, but it acts like the prop is out of the water or not turning, or i have it at full throttle in neutral. At low/mid throttle it runs great, just not at full throttle. What the hell is wrong. I've thrown my golf clubs in the river so now i must count on the boat for fun!!