Tips for buying a used boat

An engine survey primer will help you make a better decision

Steve Zimmerman, president of Zimmerman Marine has been building, repairing and refitting boats for over 40 years and has been writing tech tips for Passagemaker for over a decade.

 Note: The information below is a brief summary is for the DIYer looking to buy a used boat (for the full article click on the link that follows). However, if you are looking to purchase a used boat valued at $300,000 or more our Yacht Purchase Support team can help you at No Added cost. See below for details on our unique buyer's advocate process.

•  Before Starting the Engine: while the engine(s) are still cold you can safely crawl around with a light and mirror to look for leaks and other trouble areas. Check hoses, belts, engine mounts.

•  Underway Checks: On most engines, the rpm on the tachometer cannot be trusted as an accurate indicator. Measuring rpm at the flywheel with a strobe provides a true reading and should be compared to the boat’s tach. While underway check for smoke, vibration, and shaft seal effectiveness.

•  Taking Temperatures: While underway, use an infrared pyrometer (“temp gun”) to perform a number of checks. Just as the tach cannot be trusted, neither can the boat’s temperature gauges. A temp gun can assess performance of the heat exchanger, oil cooler, and cylinder variations.

•  Backdown Test: This test ensures that the engine will not stall under a load at idle (a good thing to know before docking) and tests the condition and installation of the engine mounts.

•  Wide Open Throttle (WOT): Failure to hit the Wide Open number as specified by the engine manufacturer indicates a problem with propeller size, fuel restriction, air restriction, the turbo or the drivetrain.

•  Back at the Dock: Once you have returned to the dock and the engines have cooled down a bit, it is time for fluid samples. At a minimum, check the engine lubrication oil and the transmission oil. Coolant samples can also be useful.