for a Safe and Smart Purchase
Buying a used boat can be a fantastic opportunity, but only if you know exactly what to look for. A careful inspection, a structured checklist, and a realistic evaluation of the boat’s condition will help you avoid costly surprises. This guide walks you through every essential step — clear, practical, and optimized for your success.
Table of Contents
1. Fiberglass (GRP) Boats – The Most Common Type
Inspecting the Hull
Never buy a fiberglass boat without inspecting the underwater hull. Trailer boats are easy to check; larger boats usually require a crane. This step is essential for identifying hidden damage.
Gelcoat & Surface Quality
Look for blisters, cracks, or peeling gelcoat. It protects the laminate from water and UV damage. Flaws in the gelcoat may indicate structural stress or previous poor maintenance.
Identifying Osmosis
Not every blister means osmosis. The classic sign is a sour smell when pricked open. Small areas can be repaired; widespread osmosis requires a professional, expensive refit.
Underwater Paint Condition
Flaking antifouling paint often results from incorrect sanding, primer choice, or poor preparation. This may require stripping and recoating later.
Cracks and Structural Stress
Hairline cracks on the transom may indicate overpowered engines. Large cracks can come from groundings or failed repairs and deserve careful evaluation.
Signs of DIY Accident Repairs
A surface resembling “orange peel” often indicates amateur paint jobs meant to conceal damage. Treat these spots with caution.
2. General Buying Advice for All Boat Types
First Impressions Matter
A clean, odor-free, and orderly boat is a strong indicator of proper care. Neglect is easy to spot and should never be ignored.
Maintenance Records
Ask for invoices and documentation. Missing records or repairs done by “friends” should raise questions.
No Compromises
If major concerns appear during the first viewing, it is better to walk away. There are always better boats on the market.
3. Sea Trial – Non-Negotiable for Any Used Boat
Realistic Test Conditions
A sea trial is mandatory. Fuel and water tanks should be filled so the boat behaves as it would during normal use.
Low-Speed and High-Speed Behavior
Start with slow maneuvers, then test acceleration and top speed. Planing boats should reach plane quickly, even without trim tabs.
Handling, Curves & Waves
Steering must remain smooth in tight turns, and the prop should not ventilate. In choppy water, stability and predictable handling are crucial.
4. Steering Systems
Smooth Operation
Cable, mechanical, and hydraulic systems all must operate smoothly, especially under load during the sea trial.
Typical Problems
Stiff steering often comes from corrosion, misalignment, or worn bearings. Hydraulic systems must be checked for leaks.
5. Wooden Boats
Material Condition
Solid wood swells; plywood does not. Rotten areas can be hidden and difficult for non-experts to identify.
Warning Signs
Dark spots beneath clear varnish indicate moisture damage. A surveyor is strongly recommended when considering wooden boats.
6. Steel Boats
Corrosion Risks
Exterior rust is easy to spot; internal corrosion may hide behind insulation or panels. Professional evaluation is advised for steel structures.
Check Anodes
Sacrificial anodes must show wear. If they look new despite age, they likely were not functioning properly.
7. Inflatable Boats (RIBs)
Always Inspect Fully Inflated
Never buy a packed inflatable boat. Inspect tubes, floorboards, transom, and accessories individually.
Common Weak Points
Chafing areas inside the tubes and cracks at the transom indicate misuse or over-powering. Avoid boats with transom cracks.
8. Engine Inspection
Cold Start Behavior
A healthy engine must start smoothly when cold. Exhaust smoke colors indicate issues: white = water, black = poor combustion, blue = burning oil.
Check Gauges & Operating Range
Look for 14 V charging, 2–3 bar oil pressure, and stable cooling temperature. Deviations can indicate hidden defects.
9. Propeller, Oil & Cooling Systems
Correct RPM at Full Throttle
Too little RPM suggests an oversized propeller or engine issues. Too much RPM suggests an undersized prop.
Water & Oil Inspection
Milky oil indicates water contamination. Metallic particles mean abnormal wear — both are serious warning signs.
10. Drives, Shafts & Vibration Issues
Corrosion & Anode Function
Anodes must not be painted and should show wear. Corroded shafts indicate insufficient protection.
Seals, Bearings & Leaks
Water intrusion creates milky gear oil. Vibrations and noise often point to worn bearings or shaft misalignment.
Vibration Diagnosis
Most vibration problems come from a bent or damaged propeller. Engine mounts, gearbox issues, or shaft misalignment can also be the cause and should be checked immediately.
Prepare Your Checklist – Download Our Free Version
Before inspecting any used boat, prepare a clean, structured checklist. It ensures that no critical point is overlooked — from hull condition to electronics, engine, fuel system, and safety equipment.
Use our free downloadable boat inspection checklist to conduct every viewing with confidence, efficiency, and professionalism.