I aquired a 1970 Rich Line 17' fiberglass fishing boat last week. Upon inspection after I got it home I realized that the previous owner was wrong it did not have a leak in the hull. The hull was full of water. I tore out the floor and foam. I am now looking for new foam to replace with. Do I need to buy a specific kind of foam or can I just go buy some "3 foam and cut to fit?