Hull and structure
For a steel vessel, the hull survey should include ultrasonic thickness testing (UTT) of the hull plating to identify any areas of accelerated corrosion or steel wastage beyond acceptable limits. Classification rules specify minimum acceptable plate thicknesses — the surveyor will compare measured thickness against class requirements and flag any areas approaching or below the limit.
For aluminium vessels, the focus is on weld quality, galvanic corrosion at the interface between steel and aluminium components, and any impact damage. GRP vessels require inspection for osmotic blistering, delamination, and any structural repairs that may not be obvious from the surface.
A haulout is strongly recommended for any vessel above €1 million — it allows inspection of the underwater hull, running gear, keel attachment, and antifouling condition that is not possible afloat. Budget the haulout cost (€5,000–20,000 depending on vessel size and yard) as part of the survey budget.
Machinery and propulsion
Main engines, gearboxes, and propeller shafts are the highest-value mechanical items on the vessel. The survey should include: engine hour records and service history, oil analysis results (which reveal internal engine condition without disassembly), borescope inspection of cylinders and turbochargers, gearbox oil analysis, shaft alignment measurements, and condition of shaft seals and stern tube bearings.
Generators, hydraulic systems (for stabilisers, bow thrusters, and tenders), and HVAC systems should all be operated under survey conditions. The sea trial provides the most definitive test — machinery should be run at varying loads for sustained periods, with any abnormal vibration, temperature, or noise immediately flagged.
Electrical and systems
Electrical system failures are one of the most common sources of post-purchase problems. The survey should cover: main switchboard condition, cable insulation testing, battery bank condition and capacity testing, shore power systems, bilge pump systems, and the condition of all navigation and communication equipment.
For vessels with complex automation systems — integrated bridge systems, building management systems, dynamic positioning — specialist technical assessment may be appropriate beyond what a generalist surveyor can provide.
Interior condition
Interior condition is difficult to survey comprehensively without dismantling, but a thorough visual inspection should identify: water ingress damage (staining, swelling, mould), joinery condition and evidence of poor workmanship, soft furnishing condition, galley and crew accommodation standards, and the overall presentation standard relative to the asking price.
Pay particular attention to the engine room, bilges, and void spaces — these reveal how the vessel has been maintained and whether water ingress has been allowed to persist.
Documentation review
The documentation review is as important as the physical inspection. Request and review: the continuous survey record from the classification society (reveals the inspection history and any overdue survey items), all maintenance records and service invoices, crew contracts and records, insurance history (claims history is relevant), and any modification records. The Lloyd's Register and IIMS can verify class status independently.
Sea trial
The sea trial should test the vessel at multiple speeds from slow ahead to full power, with sustained running at cruising and maximum speed. All navigation and safety systems should be tested operationally. The bow thruster, stabilisers, anchor windlass, and tenders should all be operated. Any system that cannot be demonstrated during the sea trial should be treated with suspicion.
Attend the sea trial personally if at all possible. Your surveyor will be taking technical measurements, but your subjective experience of the vessel at sea — noise levels, vibration, comfort at speed — is also relevant to your decision. The complete buyer's guide covers how survey findings feed into the purchase negotiation.