Definition
A sea trial is the documented on-water test programme that demonstrates a new build or used boat meets contractual performance, handling, and systems criteria before delivery or sale.
Background and use
For a new tender, the sea trial is usually a two-stage process. The builder runs internal trials (light ship, then loaded, then with deck equipment fitted) to confirm that the contract speed, fuel burn, and noise levels are within tolerance. The buyer's trial follows, often with a marine surveyor and an independent naval architect on board, and runs through the contractual acceptance schedule: top speed at full load, cruise range at 80 percent throttle, engine temperatures at sustained WOT, manoeuvring at low speed, and handling at the design sea state. Any deficiency is logged and either cured before delivery or compensated under the punch list.
For a used tender purchase, the trial is shorter but no less important. We run the boat at full throttle for a sustained 20 to 30 minutes (longer if the sale is high-value), monitor exhaust temperatures, gear-box temperatures, and oil pressures throughout, then drop power for slow-speed handling and emergency stop tests. The pre-trial survey identifies areas to push: a hull crack near a lifting point, for example, gets loaded under hard turns; a worn transom seal gets monitored under acceleration.
A failed trial is not a deal-killer; it is a renegotiation moment, settled inside the MOA's cure window.
Related considerations
- Contract speed clauses usually specify load, fuel state, and sea state.
- Trial weather can defer acceptance; build a buffer into the closing date.
- Engine logs and ECU data should be downloaded after each session.
- Independent naval architects catch issues a yard's own QA may miss.
- Insurance underwriters increasingly want sea trial reports for high-value cover.