How to buy a motor yacht — the complete guide

A motor yacht is the most capable — and most complicated — boat most people ever buy. Between the hull form, the diesel engines and the small warehouse of systems bolted around them, there are a dozen ways a beautiful-looking boat can quietly cost you a fortune. This guide walks you through what actually matters, what to survey hard, and what it really costs to keep one afloat.

Who a motor yacht is for

Motor yachts suit people who want the accommodation and the destinations without the sail-handling. You get standing headroom, real cabins, a proper galley and the ability to run a schedule regardless of wind. The trade-off is fuel and mechanical complexity: everything that makes a motor yacht comfortable — generators, air conditioning, stabilizers, thrusters — is another system that needs power, service and eventually replacement. If you love tinkering and cruising in comfort, it's the right boat. If you want low running costs and simplicity, look at a trawler or a sailing yacht instead.

What to look for when buying

Hull form decides everything else

The single most important spec isn't length or horsepower — it's hull type, because it dictates fuel burn, range and how the boat behaves in a seaway:

• Planing hulls ride up on top of the water at speed (20–30+ kn). Fast and fun, but fuel burn climbs steeply and range is short. They pound in a chop and need calm-water or coastal-hop planning.
• Semi-displacement hulls are the popular middle ground: comfortable at 10–14 kn, with a reserve turn of speed when you need it. Better sea-keeping than a planing boat, better economy than pushing a planing hull hard. Most 45–65 ft cruisers are here.
• Full-displacement hulls are limited to hull speed (roughly 1.34 × √waterline-length) but sip fuel and cross oceans. This is trawler and long-range territory — the most sea-kindly and the most economical, at the cost of top speed.

Match the hull to how you'll actually use the boat. A planing express cruiser bought for "someday we'll do the Bahamas" burns money sitting at 8 kn it was never designed for.

The diesel engine survey — where the money hides

On a motor yacht the engines are the boat's beating heart and its biggest liability. Do not rely on the hull surveyor for this — commission a separate engine survey / mechanical survey. Insist on:

• Oil analysis on each engine and gearbox — lab spectrometry flags metal wear, coolant intrusion and fuel dilution before they're visible.
• Coolant condition and the heat exchangers — milky oil or oil in the coolant points at a failing head gasket or cracked exchanger; both are five-figure jobs.
• Exhaust colour under load — black is over-fuelling/turbo, blue is oil (worn bores/valve guides), white is water or unburnt fuel. A sea trial that never leaves the dock hides all three.
• Hours vs. age — a marine diesel is often happier with steady hours than long idleness. 3,000 well-maintained hours can beat 600 hours of neglect. Read the log, not just the tach.
• Known weak points by maker — every marinized block has them (aftercooler corrosion on some Cat and Cummins units, exhaust-riser rot, wet-exhaust elbows). Ask the surveyor what this specific model dies of.

Single vs. twin: twins give redundancy and manoeuvrability but double the service, filters and eventual rebuilds. A single with a decent bow thruster is cheaper to run and simpler to keep. Shaft vs. pod: traditional shaft drives are cheap, robust and repairable anywhere. Pod drives (Volvo IPS, Zeus) give joystick docking, better economy and less noise — but pods are expensive to service, must be sealed/inspected on a schedule, and a grounding strike can be a very costly bill. Great tech; buy it with eyes open.

Big-ticket systems that make or break the deal

These are the items that quietly cost more than the engines to replace, so verify each one works, not just that it exists:

• Generator(s) — the second engine you forgot about. Check hours, run it under load, confirm it holds voltage and doesn't smoke. A dead genset on a boat with A/C and electric galley is a mandatory repair.
• Stabilizers (fin or gyro) — transform comfort at anchor and underway, and are eye-wateringly expensive to rebuild. Test them running.
• Bow and stern thrusters — check the motor, solenoids and, on hydraulic systems, the pump. Corroded thruster tunnels and seized units are common on older boats.

Hull, structure and the age-related failures

• Osmosis / blistering on older GRP hulls — moisture-meter the below-waterline laminate. Isolated blisters are cosmetic; widespread wet laminate means a peel-and-dry job that can run into five figures.
• Corrosion and bonding — inspect anodes, the bonding system, shafts, struts and through-hulls for galvanic and stray-current damage. Pink or wasted bronze is a red flag.
• Cutlass bearings — grab the props and check for play; worn cutlass bearings cause vibration and shaft wear.
• Electronics obsolescence — a "fully loaded" helm from 12 years ago may be unsupported, unable to take chart updates, and effectively worthless. Budget for a nav refit rather than paying a premium for dated glass.

What it costs to own

The old rule of thumb holds up: budget roughly 10% of the boat's value per year for all-in ownership on a used motor yacht — more on an older or complex boat, less on a simple, newer one. That figure absorbs:

• Berth / mooring — usually the biggest fixed cost, priced by length (LOA), so every extra foot costs you every month. A marina slip for a 57-footer is a serious annual line item.
• Insurance — driven by value, cruising area, your experience and survey findings. A current survey keeps premiums sane; an out-of-date one can block cover entirely.
• Maintenance — antifouling and haul-out annually, engine and genset service, anodes, impellers, plus the inevitable "while we're in there." Twins and lots of systems push this up.
• Fuel — the variable that hull form controls. A displacement boat crossing at 8 kn burns a fraction of what a planing hull burns at 22 kn; know your gph before you buy, not after.

Not sure what a boat is really worth before you factor all this in? Run it through What's it worth? for a market valuation, and see our services for surveyors, finance and transport.

New vs. used — and why buying direct wins

A new motor yacht depreciates hardest in its first few years, which is exactly why the used market is where the value is. But used boats vary wildly in how they've been kept. The best buy is almost always a well-documented boat sold directly by its owner — someone who can hand you the full service history, tell you which mechanic touched the engines, and explain every quirk. A broker-flipped boat has usually changed hands to be resold; the paper trail is thinner and the incentives aren't yours. Buying owner-direct on HulloShips means no broker commission and a real conversation with the person who actually ran the boat — which, on a machine this complex, is worth more than any glossy listing.

A pre-purchase checklist

• Confirm hull form (planing / semi-displacement / displacement) matches your intended cruising.
• Commission a separate mechanical/engine survey in addition to the hull survey.
• Pull oil and gearbox analysis on every engine; review coolant and heat exchangers.
• Sea trial at cruise and at wide-open throttle — watch exhaust colour, listen for vibration, check she reaches rated RPM.
• Read the engine and genset hour logs and service records; verify hours against condition.
• Run the generator under load; test stabilizers, bow/stern thrusters, A/C and watermaker.
• Moisture-meter the hull for osmosis/blistering; inspect below-waterline laminate.
• Check anodes, bonding, shafts, struts, through-hulls and cutlass bearings for corrosion and play.
• Assess electronics age and supportability — budget for a nav refit if dated.
• Verify steering, hydraulics and, on pod drives, the pod service and seal schedule.
• Confirm title, registration, liens and VAT/duty status are clean before you close.