“How many hours does it have?” is the first question almost every buyer asks about a used boat, and it is the wrong first question. It feels precise because it produces a number, and buyers trained on cars expect a number to mean something. On a boat, that number is one input among five, and on its own it has misled more buyers in this market than any other single figure on a listing.

Split the answer by engine type, because the spread between them is enormous and nothing else in the conversation makes sense until you do.

A four-stroke gasoline outboard is a light, high-revving engine built to a weight target. It is generally considered well used somewhere between 1,500 and 2,500 hours. A gasoline inboard or sterndrive, which spends more of its life at higher load with a heat exchanger and a raw-water circuit working against it, tends to land lower — roughly 1,000 to 1,500 hours before major work is a fair planning assumption.

Marine diesels live in a different world. A light-duty auxiliary of the kind fitted to a cruising sailboat or catamaran — the small Yanmar and Volvo Penta blocks, often on a saildrive — will commonly run 5,000 to 8,000 hours before a serious overhaul, and plenty run past that. A medium-duty diesel in a sportfish or motor yacht, worked harder and rated for intermittent recreational duty, is usually planned around 4,000 to 6,000 hours. A genuinely commercial-rated block is in another category again, with 10,000 to 20,000 hours a normal service life.

Treat all of those as planning ranges, not cliffs. Nothing fails at a round number. What actually happens is that the probability of significant expenditure rises as the hours accumulate, and the maintenance history decides how steeply.

The chart below is the same data laid out for comparison, and it makes the single most useful point in this article visible: the same hour reading means completely different things on different transoms. Four hundred hours is trivial on a Yanmar and meaningful on a big gas sterndrive.

The reason is duty rating. Engine manufacturers rate the same block differently depending on how hard and how continuously it is expected to work — a high-output recreational rating assumes short bursts of full power and long periods at part load, while a continuous commercial rating assumes the engine spends its life near its working limit. A recreational engine that has been operated within its rating and serviced on schedule ages predictably. One that has been run at wide-open throttle for hours at a time, or idled for months at a dock, does not.

Here is the part of this that brokers know and listings rarely say: for a marine diesel, low hours are not automatically good news, and are sometimes the opposite.

A diesel is happiest working. Run regularly under load, it reaches operating temperature, burns off condensation, keeps the oil circulating over every bearing surface and keeps the injectors clean. Left idle for months at a time, it accumulates water in the crankcase and fuel tank, grows biological contamination in the diesel, corrodes the cylinder walls where oil has drained away, and hardens every rubber component it owns. Raw-water pump impellers take a set. Heat exchangers silt up. Exhaust elbows rot from the inside.

So a 2,000-hour engine with a complete service log — oil and filters at interval, impellers annually, injectors serviced, valve clearances checked, coolant replaced — is a materially safer purchase than a 400-hour engine that has been started twice a year since 2020. We see both every season, and the second one is the one that produces surprise bills in the first twelve months of ownership.

The maintenance record is the document that matters, and it is the one you should ask for before you ask for the hour reading. If there is no log, treat the boat as if the work was not done, because at survey that assumption is usually correct. If the hours give you pause but the boat is otherwise right, the protection belongs in the paperwork, and the buyer clauses in the purchase agreement are what decide who pays for what the survey finds.

This is the Caribbean market’s particular quirk, and buyers arriving from the US or Europe routinely misread it.

An ex-charter catamaran coming out of a BVI fleet will show hours that look alarming beside a privately owned sister ship — often three to five times as many for the same model year. Charter engines run 300 to 800 hours a year against a private owner’s 50 to 200. On the face of it, that is a boat to avoid.

In practice it is frequently the better engine. Charter fleets service on a fixed schedule because a boat that does not start on a Saturday morning costs them a week of revenue, and the work is done by the same technicians on the same vessels year after year, with records, because the management company’s own money depends on it. Those engines run weekly, under load, at operating temperature, for their whole lives — exactly the regime a diesel wants.

The caution is that everything else on an ex-charter boat has been used by people who did not own it. Sails, canvas, upholstery, winches, ground tackle, heads and electronics all show the miles even when the engines do not. Price that in and the value case frequently still works, which is why a well-documented ex-charter boat or a charter-managed yacht coming off programme is one of the more interesting things on this market at any given moment.

Hour meters can be replaced, can fail, and on older installations can simply be wrong. They are also not tamper-proof. Nobody serious relies on the display alone, and neither should you.

Your surveyor and engine surveyor will corroborate the reading against everything else on the boat. Marine surveyors work to the American Boat and Yacht Council standards when writing findings, and a competent one will treat an hour reading as a claim to be tested rather than a fact to be recorded.

All of this belongs in the same inspection as the rest of the vessel rather than as a separate exercise. Our guide to pre-purchase survey cost sets out what a Caribbean survey runs and what the engine survey adds, and the companion piece on the survey findings that actually matter covers how to triage the report you get back so that engine hours are weighted alongside structure, rigging and systems rather than above them.

Hours affect price in a step pattern rather than a smooth curve, because buyers price the next major service event rather than the wear itself.

Through the first half of an engine’s expected life, hours barely move the number. As the engine approaches roughly 70 to 80% of its expected life, the market starts to discount — typically 10 to 20% on the vessel where the record is complete, because a buyer is now pricing an overhaul that is visible on the horizon. Past the nominal expected life, the discount reflects the full cost of a rebuild or repower, less whatever the seller has already spent, and the negotiation becomes a conversation about that one line item rather than about the boat.

The useful consequence for a buyer: a boat just past the discount threshold, with documented maintenance and a clean oil analysis, is often the best value on the market. You are paying for a rebuild that the evidence says is years away. The same logic runs through the broader question of used versus new yachts — depreciation on a hull is gentle and predictable, while depreciation on machinery is lumpy and follows service events, so the buyer who can read machinery gets paid for it.

For a seller, the arithmetic inverts. If your engines are near the threshold and you hold the records, put them in front of the buyer early. A documented service history is worth more at the negotiating table than the same money spent on cosmetics, and it is the single cheapest thing a seller can do to protect the asking price. A boat marketed with the recreational fleet’s usual opacity — and the National Marine Manufacturers Association statistics describe a fleet that is overwhelmingly privately owned and seasonally used, which is to say lightly documented — stands out immediately when the paperwork is complete.