Surveys
Sea trial testing under load, where the real faults appear
A sea trial runs the vessel under genuine load while I log RPM, pressures and temperatures and check the gauges against measured values. Engines that behave perfectly at the dock reveal overheating, fuel starvation and propeller mismatch the moment they are made to work. This is the part of a survey that cannot be faked.
Idling at the dock proves almost nothing
Plenty of tired marine diesels start easily and idle smoothly. Load is what exposes a restricted cooling circuit, a failing injector, a slipping transmission or a propeller that will not let the engine reach rated RPM. Any inspection that stops at the dock has skipped the informative half.
What is included
- Wide open throttle test for engine and propeller match
- Logged RPM, oil pressure and operating temperatures
- Exhaust gas temperature readings
- Turbo boost and fuel pressure
- Raw water inlet restriction and vacuum
- Gauge accuracy compared against measured values
- Generator run under load during the trial
- Transmission operation ahead and astern
How it works
Warm and load
The vessel is brought to operating temperature and then run up progressively while readings are logged.
Wide open throttle
Held long enough to prove the engine can sustain maximum RPM without overheating, smoking, vibrating or drinking fuel abnormally.
Log and report
Everything measured goes into the report, including where the gauges disagreed with reality.
A wide open throttle test during a marine sea trial confirms whether the propeller and engine are correctly matched, because an engine unable to reach its rated maximum RPM is being overloaded throughout normal operation.
Related surveys work
Mechanical Marine Surveys
A documented condition report on your propulsion engines and generator, from visual inspection through sea trial.
Pre-Purchase Engine Survey
The engine half of your buyer's due diligence, documented before you sign and priced against the repairs it finds.
Oil and Fluid Analysis
Laboratory analysis of engine oil, coolant and transmission fluid to catch internal wear before it surfaces.
Sea Trial Testing: common questions
Why does wide open throttle matter so much?
Because it is the one test that proves the propeller is right. An engine that cannot reach rated RPM is overloaded every hour it runs, which shortens its life and shows up as high exhaust temperatures and black smoke.
How long does a sea trial take?
Long enough to reach full operating temperature and hold wide open throttle without the engine complaining. A trial that is over in ten minutes has not tested anything.
Who drives the boat?
On a pre-purchase survey the seller or their captain normally operates the vessel while I take readings. That gets arranged as part of scheduling the trial.
Tell me what the engine is doing
Describe the symptom on the phone and most of the time the problem is narrowed before I arrive. Surveys are booked around your sea trial date.