DIY Survey Checklist for Used-Boat Buying

Before hiring a professional surveyor, look for these danger signs.

Published: June 10, 2024

Keep an eye out for corroded exhaust and signs of water intrusion, which could lead to expensive repairs in the future.

DIY Survey Checklist for Used-Boat Buying

Start by looking for obvious problems such as leaks, excessive rust, broken or missing components, and other signs of neglect. For freshwater-cooled systems, check the coolant level and properties. Lack of antifreeze should raise red flags (due to possible leaks) as should coolant with a rusty color or an unusual amount of solids.

A lot can be told by simply pulling the dipstick and checking the oil. A slightly low level might be OK, but higher than normal levels could indicate trouble, particularly if milky or frothy; both are an indication that water, antifreeze, or transmission fluid is present, signs you could be facing anything from a blown gasket to a cracked block.

Rub a little engine oil between your fingers. If it feels abrasive or has a burnt odor, be concerned about bearing wear; however, it could also simply mean the oil hasn’t been changed regularly. Wipe the dipstick on a clean white cloth or napkin. Oil thats thick initially, but then starts to spread out over the cloth is an indication of fuel contamination.

Taking oil samples to a lab for testing is a more scientific way to analyze oil condition, but it’s normally most useful in tracking issues over the engine’s lifetime, rather than for spot-checking. Still, a one-shot oil analysis can show unusual wear and the presence of water, antifreeze or diesel fuel. Think of it as a blood test for the engine—it may not predict a heart attack but it can indicate the high cholesterol that could lead to engine failure.

As for transmissions and reduction gears, dark and sluggish fluid or oil with a burned smell may indicate drive cone problems and a costly rebuild in the near future. After running the engine in gear a bit, use the dipstick to get a transmission fluid sample. Put this on a piece of paper and inspect it under a bright light or in direct sunlight for metallic specks—a sign of significant transmission wear. Inserting a long, thin magnet (the kind mechanics use to retrieve dropped bolts) through the dipstick opening and sweeping the bottom of the gearbox may produce interesting results as well.

Note how difficult the engine is to start. Depending on whether it’s gas or diesel, hard starting could be a sign of weak batteries, faulty plugs or even a bad fuel pump.

Does it run smoothly at idle and under load, or does it idle unevenly and stall out when placed in gear? Rough running can be caused by anything from clogged fuel filters to compression problems, and engines idling at more than 800 rpm may have been intentionally set to idle high to mask problems.

Verify proper oil pressure and operating temperature while the engine is running. Low oil pressure could be due to anything from faulty oil pumps to cam bearing failure. High water temperatures may be something as simple as a bad impeller, but could also be caused by corroded manifolds or exhaust risers.

Finally, read the smoke signals the engine is sending. A well-maintained engine may smoke when initially cranked or while idling, but not when warmed up or under load. Smoke color can also provide an indication of problems (blue for burning oil, black for incomplete combustion, white for water vapor, etc.).

Bottom line: Remember that hour meters mean nothing (they can easily be swapped out by an unscrupulous seller) and that an owner should eagerly provide invoices if claiming overhauls or major work has been done. Engines are a big-ticket item, so always weigh the cost of repair or replacement versus walking away.

SOFT DECKS

Water intrusion into cored decking likely causes more boat damage every year than sinkings, groundings and fires combined. Cored construction simply describes an inner and outer skin of fiberglass with some other material sandwiched between them. Most decks will be cored, typically with end-grain balsa, plywood or maybe one of the more high-tech foam variations.

The prime directive with cored construction is keeping water out. Wet wood coring can rot, which allows the cored deck to separate and drastically reduces its structural integrity. Long-term water exposure causes problems with foam-cored decks as well—core separation, freeze damage (due to expansion and contraction) and even disintegration in some cases.

Moisture intrusion into cored decking is typically caused by a combination of failed caulking and improper installation of deck-mounted hardware (cleats, lifeline stanchions, winches, etc.). Any penetration into a cored panel must be properly sealed to prevent water entry and the damage it can cause.

The first step (literally) in finding deck problems can be as simple as walking on the suspicious spots. Soft spots, oil-canning (flexing) or even water squishing from deck fittings are all indicators of a potentially expensive repair. Drips and brownish stains belowdecks are also common signs of water-soaked decks and rotting core.

Sound out the decks by tapping them with a small, plastic-headed hammer or the end of screwdriver handle. Sharp, crisp sounds while tapping are what you want, while dull thuds can be an indication of delamination. Moisture meters are also a helpful tool for sniffing out soggy decks—we reviewed our favorites here. Make sure to check out the updated moisture meter recommendations from our knowledgable commenters there as well.

Repair options are based on the core’s condition, which is determined by taking a core sample (ideally by drilling a small hole in an inconspicuous place from the inside) and looking for moisture or rot. If the coring is rotten or damaged, it must be replaced. If wet, but not damaged and there is no delamination, attempts to dry out the core can be made. Just keep in mind that it is very difficult to remove all water and that any remaining moisture will likely cause future problems. Core replacement is the only sure cure.

Bottom line: While repair costs will be directly related to the size of the delaminated area, even a minor core replacement is a time-consuming project. If faced with a large amount of deck repair, move on to the next boat or be prepared to expend a significant amount of time, money, and effort to make it right.