behind most successful used-boat transactions, there’s a purchase agreement and bill of sale that clearly spell out how the boat was bought or sold. “a purchase agreement is necessary if you intend to buy a boat, but require that certain things must be done before you will accept the boat, such as a satisfactory marine survey, specific repairs, and the ability to finance or insure the boat,” said boatus consumer protection director charles fort. once a buyer accepts the boat, the bill of sale is used as proof of purchase. the boatus consumer protection bureau offers a dispute mediation service, the only national boating complaint database, and provides consumer-oriented information to help boaters make smart buying decisions.