still heating up at 30 but figured out the problem. it has a custome build sea drive allum box on the back which is square. well if your going fast say 30 or more since the box was not tapers like the ones you can buy it directs the water away from the motor so it cannot take in much water mostly air. bad news I have to take the motor off and have the box rewelded. good news thats a cheep fix probably 40 to get re welded after I cut it up to add a taperd bottom to it. the good news is my gf loves the old boat as well it is nice to ride in just wish i lived near the ocean to really get some use out of it .