I am new to Sunfish and forums. I just bought a used one. When I turn it over I can see and hear water. It appears to be much heavier than it should. I have read about putting inspection hatches. Doesn't seem like there is much to it. I have found very little about water logged styrofoam. Also, I have no idea of it's age Can I locate where to put a port by going to a spot that sounds hollow?