Why a Marine Survey Matters — and What It Covers

A marine survey is an independent expert's stem-to-stern inspection of a vessel, documented in a formal report. It is the single most important step in buying a used boat.

Why do you need one?

Problems invisible from the outside — osmosis, fatigued rigging, low engine compression, amateur electrical work — only surface under an expert eye. The report does three jobs: you learn the true condition, you gain concrete data for price negotiation, and insurers usually require a recent survey.

What does a survey cover?

• Hull: impacts, cracks, osmotic blistering; rot and caulking on wooden boats
• Engine and gearbox: hours, compression, leaks, cooling system
• Electrics and electronics: wiring quality, battery banks, navigation equipment
• Rig and deck gear: mast, rigging and sails (on sailing yachts); windlass, steering
• Safety equipment: fire systems, bilge pumps, liferaft certification

What does a sea trial show?

Issues that never appear alongside — vibration, overheating, steering play, true speed — show up under way. On our listings, the "sea trial available" flag means the seller offers this.

What if the report is bad?

Defects are a negotiating lever: you can ask for a price reduction, require repairs before transfer, or walk away. This is why you should use inspection and survey opportunities before bidding at auction — bids are binding.