Originally Posted by jethro110
I believe the engine and boat have always been together. The previous owner said he used to get 35+ knots out of it. This leads me to believe it is more likely to be engine related than the prop, although I will check to be sure.
The hull has no water in it
Based on that I agree probably not prop or "lard" issures.
Cheap & easy test - change the plugs. If it makes s*d all difference, start deep diving the rest of the engine.
(while you are there, if yours is a merc based one, have a check of the spark plug leads - one of mine the connector had fatigued off the end of the wire & was only held connecting by the rubber seal - of the other 2, one wasn't too far behind it.