Pre-purchase survey: what to expect on the day

A pre-purchase survey is three to six hours of methodical, fairly unglamorous work: tapping, metering, poking, photographing and writing. Knowing the shape of the day makes it far easier to get value from it — and to understand what the report is and is not telling you.

Before the day: what you need to arrange

Two things have to be in place, and neither is the surveyor's to organise.

The lift out. A pre-purchase survey means the vessel out of the water. Ring the yard early: crane and hoist slots are frequently the longest lead time in the whole process, and in spring they can run weeks ahead. Ask the yard to pressure-wash the hull immediately after lifting, while growth is still soft. Once it dries and sets, it comes off badly and hides the gelcoat underneath.

Access. Ask the broker or vendor to empty lockers, lift sole boards, clear the engine bay and pump the bilges. This is not fussiness. Anything the surveyor cannot reach gets written up as not inspected, and every one of those lines is a gap in what you know about the boat you are buying. There is a full checklist in how to prepare your boat for a survey.

Also worth doing beforehand: confirm with your insurer what they will require, so one survey serves both purposes. And ask the vendor for the paperwork — registration, previous surveys, service history, VAT status, any receipts for major work. Documents often explain what the surveyor finds.

Arrival and first impressions

The first fifteen minutes are spent walking round the boat saying very little. General impressions matter: how she sits in her cradle, whether the hull sides are fair, whether previous repairs are visible in raking light, whether the antifoul has been slapped over something.

The kit is unremarkable — a moisture meter, a phenolic hammer or nylon mallet for sounding, a mirror, torches, a spike for probing timber, calipers, a camera, and knee pads. There is no clever instrument that sees inside a laminate. Surveying is pattern recognition built on having seen a lot of boats and repaired a fair number of them.

The hull, out of the water

This is where the largest share of the time goes, and it is why afloat inspections are so limited.

• Sounding. The hull is tapped systematically. A sound laminate rings; delamination, voids and wet core give a duller, deader note. It sounds crude and it is remarkably effective.
• Moisture readings. On GRP, readings are taken in a grid, with anything elevated mapped and re-checked. Readings are comparative, not absolute — see the article on osmosis for why a single number means very little on its own.
• Keel and keel joint. On a fin-keeled yacht, the hull-to-keel joint and its bolts get particular attention. Smiles, weeping and movement here are serious.
• Rudder, skeg and stern gear. Rudder stock play, bearing wear, water inside the rudder blade, shaft alignment, cutless bearing wear, propeller condition, anodes.
• Skin fittings and seacocks. Every one, checked for material condition, dezincification, operation and hose condition. Perished hoses and rusty single clips below the waterline are extremely common and cheap to fix.
• Previous repairs. Grounding damage, impact repairs and blister treatments are usually detectable, whatever the paint suggests.

Deck, superstructure and rig

Decks are sounded in the same way as the hull, because most GRP decks are cored — balsa, plywood or foam between two skins. Water gets in through unsealed fastenings, stanchion bases, cleats and window frames, and once the core is wet it loses strength and rots. This is one of the more expensive findings, and one of the least visible: a wet deck can look perfect.

Also covered: window and hatch seals, non-slip condition, stanchions and guardrails, deck gear and its backing plates, anchor windlass installation, and any signs of movement around highly loaded fittings.

On a sailing vessel, the rig is inspected from deck level — mast heel and step, deck collar, boot, visible standing rigging terminals, swages, chainplates and their bedding, boom fittings, running rigging condition. Masthead and upper rigging need the rig out or a climb, and that is arranged separately. If the standing rigging is over about ten years old and undocumented, expect a recommendation to replace it regardless of how it looks; that is £3,000–£5,000 on a 38-footer and belongs in your budget.

Below decks and inside the structure

Inside, the interest is structural rather than cosmetic. Bulkheads and their tabbing to the hull, stringers, frames, floors, engine bearers, mast step area, chainplate backing, tank mountings. Water staining, rust weeps, cracked tabbing and softened plywood all tell a story.

Bilges get particular attention, which is why pumping them beforehand matters so much. Standing water hides exactly the areas you most want to see, and oil in the bilge tells you something about the engine before the engine is even looked at.

Damp meter readings are taken internally too, and internal readings on a hull that has been ashore a while are often more informative than external ones.

Engine bay, systems and safety gear

Be clear about the boundary here. The engine bay is inspected visually: mountings, alignment where visible, obvious leaks, corrosion, exhaust condition, hoses and clips, belts, raw water system, stern gland, wiring standard, insulation, fire protection. What is not included is internal engine health — compression, oil analysis, injector condition, gearbox internals. That needs a marine engineer, typically £250–£600, and on a boat where the engine is a large fraction of the value it is money well spent alongside the survey.

Also covered: the electrical installation to a condition standard, batteries and charging, gas installation and its ventilation and shut-offs, freshwater and waste systems, bilge pumping arrangements including automatic pumps and float switches, steering system, and the safety equipment present with its expiry dates.

What cannot be inspected, and why it matters

A survey is non-destructive. Panels, linings and headlinings stay in place; fitted joinery is not cut out; tanks are not opened. This is the correct approach on a boat you do not yet own, but it does mean genuine blind spots.

The measure of a good report is that it says so explicitly. A line reading "hull behind fixed joinery in the forward cabin not inspected — access not available" is worth far more to you than silence, because it tells you precisely where your risk is unquantified. A report with no such limitations listed has either had extraordinary access or is not being straight with you.

Where something is significant but unreachable, expect a recommendation for further investigation. Take those seriously — they are the surveyor telling you there may be a problem they were not permitted to confirm.

The report, and how to read it

The written report normally follows within two to five working days. Expect a description of the vessel and the conditions of inspection, the findings section by section, photographs of anything significant, a summary of limitations, and recommendations grouped by urgency.

Read it in this order:

1. The limitations and scope. Establish what was and was not inspected before you read a single finding.
2. The highest-urgency recommendations. Structural items, anything affecting watertight integrity, anything affecting safety.
3. The medium-term list. Work needed within a season or two — usually the bulk of any renegotiation.
4. The routine maintenance list. Perished hoses, corroded clips, out-of-date flares. Normal ownership.
5. Then go back and read the whole thing properly.

Do not be alarmed by length. A thirty-year-old boat generating forty findings is entirely normal; a clean report on the same boat would be more worrying. What matters is the category, not the count.

What to do with the findings

Ring the surveyor and talk it through. A conversation about which three findings actually matter is usually the most valuable twenty minutes of the whole exercise, and with Infinity Marine it is included rather than billed.

From there you have the normal options: proceed as agreed, renegotiate on the basis of quantified work, ask the vendor to complete specific items before completion, or walk away. All four are legitimate outcomes of a good survey. Buyers routinely use a report to revisit price, and a well-evidenced report is hard for a vendor to dismiss precisely because it is independent.

One thing a surveyor should not do is quote for the repairs they have just identified — that conflict undermines the independence you paid for. Help scoping the work and arranging comparable estimates from yards and trades is a different matter, and thirty years in boat building and repair is genuinely useful at that stage.

Related reading

• How much does a boat survey cost in the UK?
• How to prepare your boat for a survey
• Osmosis in GRP boats: what it is and what it costs
• Frequently asked questions

This article is general guidance, not advice on a specific vessel, and does not replace a survey. Cost figures are indicative UK market ranges as at August 2026 and are not quotations.