I am considering buying a Chaparral 2004 18 ft I/O with 13 hrs of operation in salt water for one year. It had bottom paint so it may have been on a mooring or slip. I will be using the boat in fresh water. The boat appears to be in excellent shape. I do not see any exterior salt water damage. The boat is 150 miles away so I can't have my mechanic survey the boat. The dealer bought the boat in a repo auction; I am getting an excellent price. The dealer warrants the engine and drive train for one season. How can I inspect the boat engine for salt damage?