The boat maintenance checklist that actually gets done

Five minutes before you cast off

• Engine bay sniff-and-look — fuel smells, oil or coolant under the engine, loose belts.
• Oil and coolant levels — 30 seconds with the dipstick saves engines.
• Raw-water flow — after starting, check water is spitting from the exhaust.
• Bilge check — dry-ish, pump switched to auto, float switch free.
• Safety kit aboard — lifejackets, kill cord, VHF check, fuel reserve for the plan.

The habits that catch problems early

• Batteries — voltage, terminals clean and tight, secure mounting.
• Seacocks — work every one open/closed so none seizes in an emergency.
• Bilge pumps — lift the float switch and hear each pump run.
• Belts and hoses — cracking, softness, weeping jubilee clips.
• Lines and fenders — chafe at fairleads and cleats.
• Log it — engine hours and anything you noticed. Trends beat memories.

Before she goes back in

• Antifoul and hull inspection — blisters, cracks, keel and rudder condition.
• Anodes — replace at ~half wasted; investigate unusually fast erosion.
• Engine service — oil + filters if not done at lay-up; impeller in; belts tensioned.
• Skin fittings and hoses — double-clipped below the waterline, seacocks smooth.
• Safety dates — flares in date, fire extinguishers, liferaft service, gas system check.
• Rig and steering — standing rigging eyeball, steering lock-to-lock, cables greased.

Winterise it properly, launch it easily

• Engine — winterise the raw-water side (drain or antifreeze), change oil while warm (old acidic oil shouldn't sit all winter), fog petrol engines per the manual.
• Fuel — treat diesel against bug, then follow your engine maker's guidance on tank levels.
• Fresh water & heads — drain systems and calorifier, pump antifreeze through as needed.
• Batteries — fully charged, isolated, ideally on a maintainer.
• Ventilate — a dry, aired boat under cover beats a sealed damp one every time.

The rule-of-thumb service intervals

• Every 100 hours or annually — engine oil + filter (whichever comes first).
• Annually — raw-water impeller, fuel filters/separator, air filter check.
• Every 2 years — coolant, gearbox/outdrive oil (often yearly — check the manual).
• Watch the trend — rising oil consumption or temperature over months is your earliest warning. You only see trends if the hours and services are written down.

Intervals vary by engine — the manufacturer's schedule always takes priority.

Quick answers

How often should I service the engine? Rule of thumb: oil + filter every 100 hours or annually; impeller and fuel filters yearly. Your engine manual overrides.

When do anodes need replacing? At ~half wasted — and fast erosion is worth investigating, not just replacing.

Why log maintenance at all? Trends catch problems early, and a dated service history is one of the first things buyers and surveyors ask for.