Also the little pump with the small fan belt is your fresh water pump. The inside impeller has to be replaced. Most people do it every wear. The easiest way to do this is to remove the whole thing because the plate you take off is inboard to the engine. It is impossible for me to replace the impeller with out removing the pump. But that's me. Lots of info on this engine. Keep searching.
That derelict boat was another dream for somebody else, don't let it be your nightmare and a waste of your life.