Winterising and recommissioning a boat: the list of jobs

Winter damages boats more than sailing does: frost in a water circuit, flat batteries, mould in a closed-up saloon, diesel that clogs, an engine that rusts from the inside for lack of running. A well-done winterisation is a morning’s work in autumn and a morning in spring — and it is what separates, after ten years, a “used” boat from a “tired” one. Here is the list, in the order you do it, showing what changes depending on whether the boat comes out of the water or stays afloat.

1. Ashore or afloat?

Hauling the boat out protects the hull bottom (no fouling, osmosis does not progress), the engine (in the dry, through-hulls out of the water) and gives you the chance to check everything below the waterline: anodes, through-hulls, propeller, rudder, stern gland. On the other hand: lifting, storage fees, and the boat must be properly chocked and covered. Staying afloat costs less but means closing the through-hulls, keeping an eye on mooring lines and fenders, and visiting regularly. Either way, the logic is the same: drain, protect, ventilate, disconnect.

2. Winterisation: the engine

This is the item that forgives least. The principle: an engine is winterised with fresh oil, a protected cooling circuit and a full tank.

• Engine oil and oil filter change, with the engine warm: used oil is acidic and attacks the bearings over the winter. It is the annual service, best done in autumn rather than in spring.
• Diesel filters (water-separating pre-filter and fine filter) if they are nearly due; drain the water from the separator.
• Raw water circuit: flush with fresh water, then have the engine draw a non-toxic antifreeze until it comes out of the exhaust. Ashore, then open the raw water strainer and leave the impeller at rest (some people remove it so it does not take the shape of the pump housing).
• Closed fresh water circuit: check the antifreeze protection of the coolant, replace it roughly every two years.
• Full diesel tank with stabiliser added: a half-empty tank condenses, and the water feeds the bacteria that clog the filters in spring.
• Gearbox or saildrive leg: oil level, change if it is due; milky oil signals water ingress to deal with before spring.
• Spray a protective product on the engine, grease the controls, leave the engine compartment ventilated.
• Outboard: flush with fresh water, drain the gearcase (milky oil = seal to replace), fog the cylinder, store upright, and empty the carburettor or stabilise the petrol.

3. Winterisation: water circuits and comfort

• Drain the fresh water tanks, the water heater and the pipes; run the pumps dry for a few seconds; leave the taps open.
• Marine toilets: flush with fresh water, drain the bowl and the pump, protect with a food-grade antifreeze if the boat may freeze. Empty and rinse the black water tank.
• Fridge and cool box: emptied, cleaned, door wedged open.
• Gas: close the bottle, check the date of the hose and the regulator.

4. Winterisation: electrics

• Batteries: charge fully, clean and grease the terminals, check the levels (flooded batteries). Either disconnect them and leave them on board in the dry, or leave a maintenance charger on if the boat is connected to shore power.
• Switch off all circuits at the panel; disconnect any sensitive electronics that can be removed (portable GPS antenna, handheld VHF).
• Take off anything that fears damp (computer, tablet, cameras) and the paper charts.

5. Winterisation: deck, rigging, sails

• Sails: taken off, rinsed, dried, folded or loosely rolled, stored in the dry — not in a damp locker. A season left on the furler in the marina damages a genoa more than ten outings.
• Sprayhood, bimini, mainsail cover: rinsed and stored; the winter cover goes on instead.
• Running rigging: halyards rinsed, replaced by messenger lines if they would spend the winter in UV light. Standing rigging: visual check of the swages, bottlescrews and pins — this is the time to spot a broken strand.
• Winches greased, sheaves and blocks rinsed, stanchions and guardrails checked.
• Ground tackle: chain rinsed and dried if possible, windlass greased.

6. Winterisation: hull, safety, interior

• Ashore: pressure-wash on haul-out, photo of the hull bottom, check of the anodes, the through-hulls (greased every two years, boat ashore), the propeller, the cutless bearing and the rudder.
• Afloat: close all through-hulls except the bilge pump outlet; double up the mooring lines, add fenders, check the automatic bilge pump.
• Safety: note the dates of the liferaft (service), the distress flares (expiry), the fire extinguishers (annual check), the inflatable lifejackets (annual service) — winter is the time to send them for servicing.
• Interior: take out or stand up all soft furnishings, open the floorboards and lockers, a dehumidifier or moisture absorbers, permanent ventilation (wind scoop, hatch left ajar under the cover). A boat sealed tight smells of mould by March.
• Take the boat’s papers and valuables home; leave on board a note with your phone number, visible from outside, for the harbour office or the boatyard.

7. Recommissioning in spring

Spring is not the mechanical reverse of autumn: it is a check. Everything that was opened or drained is closed again, and everything noted in autumn is dealt with before relaunching.

• Engine: oil level, raw water pump impeller (refitted or replaced — every year or 200 hours), belt (check, replace at around 500 hours), heat exchanger anode, raw water strainer closed, hose clips tight, bleeding of the diesel circuit.
• Refill the fresh water, rinse the tanks if a product has been used, put the pumps back into service and purge the air.
• Batteries: resting voltage, terminals, full charge before the first start.
• Hull bottom: antifouling if it is due (see haul-out and antifouling), new anodes, through-hulls operated, depth sounder and log transducers cleaned.
• Rigging and sails: sails bent on again, halyards rerun, standing rigging checked when re-tensioned.
• Safety: equipment back from servicing put on board, dates checked, full safety kit for the sailing area.
• After relaunching, before leaving the pontoon: open the through-hulls one by one watching for leaks, stern gland (a few drops a minute for a packed gland, dry for a lip-seal type), start the engine and check water at the exhaust, temperature after ten minutes, ahead and astern, steering response.

8. What matters for the future: write it down

Winterisation is only worth something if it leaves a trace. The engine hours at the oil change, the date of the antifreeze, the photo of the hull bottom at haul-out, the receipt for the filters, the boatyard’s invoice: in the log, all of this becomes a dated job with its level of proof — declared, documented or confirmed. On the day of the sale, ten documented winterisations in a row carry more weight than a nice photo. The maintenance cost guide puts these jobs into the annual budget.