Most people inspect a boat in the wrong order. They walk the deck, sit at the helm, imagine a Saturday, and only then look at the engine, by which point they have already decided to buy it. Do it backwards and you will walk away from more boats, which is the point.

Check the expensive things first

A boat is really three purchases stacked together: an engine, a hull, and a trailer. They fail at wildly different prices. A repower runs $15,000 to $30,000. Structural work on a rotten transom or stringers can run five figures and takes the boat off the water for a season. A trailer is $1,500 to $5,000. Cosmetics, upholstery and electronics are rounding errors next to those.

So look at them in cost order. Engine, structure, trailer, then everything else. If the first one fails, you are done, and you have saved yourself an hour of being charmed by a nice cooler seat.

The order you inspect in decides what you notice. Cost order keeps you honest.

1. The engine, before anything else

Ask the seller not to start or warm the engine before you arrive, and say so when you set up the viewing. A cold start tells you far more than a warm one. An engine that has been running for twenty minutes before you pull in is hiding something more often than not.

What you are looking for, roughly in order:

  • Does it start cold, without ether or a long crank? Hard cold starting on a four-stroke outboard is a real signal, not a quirk.
  • What comes out of the exhaust in the first thirty seconds? Some smoke and steam is normal. Blue smoke that keeps going, or a sweet smell, is not.
  • Water pump. There should be a strong, steady stream from the telltale. A weak dribble means an impeller at minimum, and an overheated powerhead at worst.
  • Oil. Pull the dipstick on a four-stroke. Milky or over-full is water in the oil, and water in the oil is the end of the conversation.
  • Lower unit oil. Ask when the gear lube was last changed and whether it came out milky. This is the cheapest question with the most expensive answer.
Close-up of an outboard lower unit and propeller
Chips in the blades are a cheap fix. What sits behind them, at the bottom of the leg, is the part that decides whether the engine is worth anything.

What a compression test actually tells you

A compression tester screws into a spark plug hole and reads the pressure that cylinder builds while the engine cranks. You are not looking for a magic number, because what counts as healthy varies by engine. You are looking for consistency across cylinders. If one is meaningfully lower than the others, that cylinder has a problem, and on an outboard that usually means the powerhead comes apart.

It is a twenty minute job and it is the single highest-value check you can run on a used boat. If a seller will not let you do one on an engine they claim runs fine, that refusal is your answer.

Phrases that mean the engine is the problem

"Ran when parked", "turns over but won't start", "just needs a tune up"
"Needs carb work", "no compression", "lower unit issue", "needs a powerhead"

Any of these and you are not buying a boat, you are buying a hull with an anchor bolted to the transom. Price it that way or move on. This is exactly what DockSnipe flags before you drive out.

2. Structure, which is what actually ends boats

Engines can be replaced. A rotten stringer grid usually cannot be, economically. Fibreglass boats absorb water through old fastener holes and bad bedding, and the wood underneath goes soft while the outside still shines.

  • Walk the deck in bare feet or soft shoes, the whole deck, especially around the console base, hatches and any deck fitting. Sponginess or a dull, dead feel underfoot means water in the core.
  • Grab the outboard and lift. With the engine tilted, pull up and push down on the powerhead. Any flex or creak in the transom is a serious finding.
  • Tap along the transom and deck with a plastic mallet or the handle of a screwdriver. Solid glass rings sharp. Wet core thuds.
  • Look in the bilge with a real light. A bright inspection light shows you standing water, rust stains, cracked stringers and sloppy repairs that a phone torch will not.
  • Check for repairs that do not match. A patch of gelcoat in a slightly different white, or fresh paint only on the bottom of the transom, is worth asking about directly.
A weathered runabout pulled up on a stony shore
Nothing visible here tells you whether the deck is solid. That is the problem with structure: it fails from the inside out.

If you are looking at boats regularly, a moisture meter is worth carrying. It reads moisture through the laminate and turns "I think this feels a bit soft" into a number you can point at while you negotiate.

3. The trailer, which people forget until they cannot leave

The trailer is a vehicle with its own failure modes, and it is often the part that has sat outside untouched for years while the boat was covered.

An aluminium boat sitting on a single-axle trailer parked at the kerb
Walk the trailer end to end before you talk about the boat. Wheels, lights, coupler, chains, and whether there is a second title for it.
  • Bearings. Jack a wheel off the ground and spin it. Grinding, roughness or play means new bearings, and bearings that fail on the highway can take the whole hub with them. A bearing kit is cheap; a roadside failure with a boat on the back is not.
  • Tyres. Look at the date code, not the tread. Trailer tyres die of age and sunlight long before they wear out, and a five-year-old tyre with perfect tread will still come apart.
  • Lights and wiring. Have someone work the pedal and indicators while you watch. Corroded connectors are normal, a rotten harness is a half-day job.
  • Frame and welds, especially at the crossmembers if it has ever lived in salt.
  • Winch strap and safety chain. Cheap to replace, and a good sign of how the owner treated everything else.

4. Titles, before money changes hands

In most states the boat and the trailer carry separate titles. Check both, check the hull identification number on the transom against the paperwork, and check that the name on the title is the person standing in front of you.

"Bill of sale only" is not automatically a dealbreaker, and plenty of legitimate boats have messy paperwork. It is a discount and a delay, and you should know which one you are dealing with before you drive out, not after.

Three findings should end a viewing early: water in the oil, a transom that moves, and a title that is not the seller's to give.

What to bring

None of this needs a workshop. A compact kit covers almost every check above:

Prices move around, so check the current one before you buy anything.

The part that is not on the boat

Ask how long they have owned it, why they are selling, where it has been stored, and when it last ran. Then stop talking. Sellers fill silence, and what they fill it with is usually the thing you most needed to know.