My wife and I have just purchased a 1995 Hunter 36 Vision sail boat and are in the process of repairing the fresh water tank. The water tank is 75 gallons (sort of L shaped) and has a pin hole on the top corner of the seam where the L shape is. The tank is white and translucent. I have use JB weld in a tube and a JB in a putty to no avail. Does anyone know what the tank is made of? Does anyone have any tips on how to repair it?