The short version
- Ask for the engines cold. A cold start tells you things a warmed-up engine hides.
- The wide-open-throttle RPM is one of the most diagnostic numbers you will get.
- Run every system you will rely on, not just the ones the seller demonstrates.
- Keep the trial and the survey together: your surveyor should be aboard.
The sea trial is usually scheduled alongside the survey, and in most contracts it is part of the same acceptance contingency. Treat it as an inspection, not a ride.
At the dock, before you leave
- Ask for cold engines. Request that the engines not be run before you arrive. Watch for smoke, hard starting and noises that fade once things warm up.
- Look in the engine room before and after. Note any oil, coolant or fuel residue, and check again on return.
- Check the bilges. A dry bilge before departure is your baseline.
- Run the generator under load with the air conditioning on.
- Test electronics at the helm: plotters, radar, autopilot, VHF and instruments should all power up and agree with each other.
Under way
- Steering: smooth, quiet and centred, with no play or binding lock to lock.
- Shifting: clean engagement in forward and reverse, at idle and slightly above.
- Vibration: feel for it through the deck and the helm at different RPMs. Vibration at a particular speed often points to running gear: props, shafts, cutlass bearings.
- Gauges: temperatures and oil pressures should settle and stay steady. Note them at several RPM steps.
- Handling: how she tracks, turns, and behaves in a following sea if you can find one.
Wide open throttle
Run up to full throttle and hold it briefly while the engine surveyor records data. The engines should reach the manufacturer's rated RPM. If they fall short, something is off: a fouled bottom, wrong propellers, an overloaded boat or an engine down on power. It is one of the most useful single readings in the whole inspection.
Every system you will use
Thrusters, stabilisers, windlass, davit or crane, swim platform, watermaker, tender launch, hot water, heads, galley appliances. If you will rely on it, run it. Sellers naturally demonstrate what works best.
On return
- Re-check the engine room and bilges against your baseline.
- Dock the boat, or watch it docked, to see the thrusters and controls in close quarters.
- Write down what you saw while it is fresh, and compare notes with your surveyor before you leave the dock.
Common questions
Who pays for the sea trial?
Typically the buyer pays the survey and haul-out costs, while the seller provides the boat and captain for the trial. Fuel arrangements vary; agree them in advance.
Should my surveyor be on the sea trial?
Yes. The hull surveyor and the engine surveyor should both be aboard. Much of what they report depends on what they observe under way.
What if the engines don't reach rated RPM?
Treat it as a finding to investigate. Causes range from a fouled bottom or wrong propellers to an engine problem. Your engine surveyor will help separate them.
Talk it through with Kevin
Coast Guard veteran. Fifteen years at Denison Yachting, where he managed new-boat sales for Selene and Hatteras. Founded Resolute in 2021.