Surveys
Pre-purchase engine survey before you sign for the boat
A pre-purchase engine survey tells you the condition of the propulsion engines and generator on a boat you are about to buy. It is separate from the hull survey and it is where the largest hidden costs on a diesel vessel are found. You get compression figures, load test results, lab fluid analysis and a photographed report you can negotiate with.
The engines are the biggest number nobody checked
Buyers routinely commission a hull survey, get a machinery section that reports only what was visible, and close on the vessel with no real information about the engines. A pair of tired yacht diesels can carry a repair bill larger than the deposit. The survey costs a fraction of that and it happens while you still have room to renegotiate.
What is included
- Cold engine room inspection before anything is started
- Compression on every cylinder with injectors removed
- Engine management and fault code history
- Alternator output, starter draw, voltage and belt tension
- Wide open throttle test for engine and propeller match
- Sea trial with logged RPM, pressures and temperatures
- Oil, coolant and transmission fluid sent for laboratory analysis
- Written report with a photograph against each finding
How it works
Book around the sea trial
Engine surveys are usually scheduled alongside the hull survey and sea trial so the vessel only gets moved once. Call as soon as you are under contract, because yard and trial slots set the timeline.
Inspect, test, sample
Cold inspection, then dock trial with compression testing, then the sea trial under load. Fluid samples are drawn and sent out the same day.
Report and next steps
You get the written report with photographs, an explanation of what each finding actually means for cost, and a straight answer about what would need doing and roughly when.
A pre-purchase engine survey examines the propulsion engines and generator separately from the hull survey, and is the stage at which compression testing, engine management diagnostics and laboratory fluid analysis are performed on a diesel powered vessel.
Related surveys work
Mechanical Marine Surveys
A documented condition report on your propulsion engines and generator, from visual inspection through sea trial.
Oil and Fluid Analysis
Laboratory analysis of engine oil, coolant and transmission fluid to catch internal wear before it surfaces.
Video Borescope Inspection
A camera inside the cylinders and passages, so the decision to open an engine is made on evidence.
Pre-Purchase Engine Survey: common questions
Is an engine survey included in a regular boat survey?
Usually not. General marine surveys typically cover machinery as a visual overview and refer detailed engine diagnostics to a qualified mechanic. On a diesel powered boat the engine survey is a separate engagement, and it is the one that carries the largest numbers.
When in the buying process should the engine survey happen?
After you are under contract and before the inspection contingency expires, normally on the same day as the hull survey and sea trial. That way the boat is only hauled and run once.
What if the survey finds a serious problem?
Then it has paid for itself. You get the finding documented with a photograph and an honest estimate of what it takes to correct, which is what you take back into the negotiation or use to walk away.
Do you survey boats you might later repair?
I will tell you plainly what I find and what it would cost. If you would rather have the repair quoted by someone else afterwards, that is entirely reasonable and the report is written so any competent shop can work from it.
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.