Most boats wear out not at sea but while they wait ashore or on a berth through the winter. Damage from a season's sailing is predictable; damage from a badly spent winter is insidious, a frozen circuit, a sulphated battery, an interior going mouldy under a cover, a gland drying out and cracking.
This page puts winter preparation in order and shows the mistakes made most often.
Ashore or afloat? Both are common in Türkiye. A boat ashore dries out, an advantage for moisture readings, a disadvantage for timber detail and glands. A boat afloat holds her moisture balance but keeps consuming anodes, and stray current and flooding risk continue. If you are buying, a boat that has stood ashore is preferable: only then is a hull reading meaningful.
- Water systemsdrain and antifreeze
- Engineoil, filters, coolant
- Batteriescharged and monitored
- Hullclean and inspect
- Coverventilation essential
From the field
The most common winterising mistake is covering a boat early and tightly. A cover is there to keep rain out, not to stop air moving. A boat with no airflow underneath has a damper winter than one left open.
The second: letting the batteries go flat. A lead-acid battery left discharged sulphates, and in spring it does not give all of its capacity back.
1. Engine and Drive
- Oil and filters are changed going into winter, not coming out. Acid and water in used oil should not sit inside an engine for four months.
- The coolant circuit is protected with antifreeze; the raw water circuit is drained or filled with a suitable mixture. A frozen heat exchanger is a spring replacement.
- The fuel tank is left full, an empty tank condenses, and water is where microbial contamination starts. Consider a stabiliser and, where appropriate, a biocide.
- Drain the water separator, renew filters.
- Remove the impeller to prevent it taking a set; fit a new one in spring.
- Shaft gland: a long spell ashore dries a traditional packing; check for leakage in the first hours afloat.
2. Electrical and Batteries
- Batteries are left fully charged. A lead-acid battery left flat sulphates and never returns its capacity, the most expensive silent damage of winter.
- If charging is left on, it must be a charger with a float profile suited to the battery type. The wrong charging cooks a battery over a winter.
- Main isolator off; bilge pump and alarm stay live (mandatory on a boat afloat).
- Check connections, clean and protect terminals; damp destroys a loose terminal quickly.
- On a boat afloat, watch galvanic protection: stray current from the shore supply is the largest consumer of anodes over winter.
3. Water Systems and Plumbing
- Fresh water tank and lines drained, or protected with potable antifreeze. Pump, calorifier, shower and basin lines are all part of it.
- Heads and holding tank drained and cleaned, this solves odour and freezing at once.
- Drain raw water from air-conditioning and refrigeration circuits.
- Seacocks: left closed ashore; in spring each one is operated individually. A valve that froze over winter breaks when forced in spring.
- Leave the bilge dry; standing water freezes and expands.
4. Hull, Deck and Interior
- Pressure-wash the bottom as soon as she is lifted, dried growth is three times the work later.
- If a cover is used, leave ventilation. A fully sealed cover creates a greenhouse and is mould's best friend.
- Inside, leave locker doors and hatches open, stand cushions on edge, use a dehumidifier or moisture absorber.
- Clean and lubricate deck gear (winches, windlass); salt works away all winter.
- Remove sails, dry them, store them dry. A furled sail left on a forestay loses a season's life to UV and damp in one winter.
- Keep bilge, tank and locker ventilation open.
5. How She Stands Ashore
How a boat is supported on the hard determines the load she carries all winter. A badly placed pad can leave permanent deformation at the keel root or in the topsides. What to check: is the keel fully bearing, do the side supports land on structural points, is the ground sound (will it subside in rain), is there additional securing for a gale. Your policy may set conditions for laying up ashore, check it.
6. The Ten Most Common Mistakes
| Mistake | Consequence |
|---|---|
| Leaving batteries flat | Sulphation; capacity permanently reduced, the bank is replaced in spring |
| Leaving the fuel tank half full | Condensation, water, microbial growth; injector and filter trouble |
| Changing oil in spring instead of autumn | Acid in used oil sits inside the engine for four months |
| Sealing the cover completely | Mould, odour, permanent staining in upholstery and timber |
| Not draining the water system | Freezing: cracked pump, calorifier and pipework |
| Leaving a sail on the forestay | UV and damp; stitching and cloth life gone in one winter |
| Leaving water in the bilge | Expansion on freezing, odour, damp in interior timber |
| Not checking anodes | Consumption accelerates over winter on a boat afloat |
| Not checking how she is propped | Permanent hull deformation, strain at the keel root |
| Launching in spring without testing seacocks | A valve breaks and she takes water |
7. Spring Checklist
- Operate every seacock and check it seals.
- Fit a new impeller, fill and bleed the cooling circuit.
- Test the battery bank; replace as a set where capacity has dropped.
- Flush and sanitise the fresh water system.
- Check anodes; replace anything below half.
- Check rig tension and inspect terminals.
- Watch the shaft gland during the first hours afloat.
- Check safety equipment dates (liferaft, flares, extinguishers).
- Test the bilge pump and alarm.
- Build up load gradually on the first outing; do not go straight to full revs.
From a survey point of view: a condition survey before or after lay-up is the most economical preparation for anyone thinking of selling, findings are rectified out of season, without haste and at lower cost. Knowing what the buyer's surveyor will find is the strongest position at the negotiating table.
Frequently Asked Questions
It depends on your plans and budget. Ashore she dries, good for moisture readings, less good for timber and glands. Afloat she keeps her moisture balance but anode consumption and stray current continue.
Not necessarily, but they must be fully charged. If you do remove them, store them cool and dry and check the charge monthly. A battery left flat sulphates and does not come back.
Full. An empty tank condenses, water collects and microbial growth starts. Consider a stabiliser and, where appropriate, a biocide.
Not essential but useful, provided it breathes. Mould develops under a fully sealed cover. A system that allows circulation beats both no cover and a sealed one.
Very much. The boat is already ashore and dried out, ideal conditions for moisture readings. If you are thinking of selling, rectifying findings out of season is both cheaper and calmer.
Monthly is enough; always after a gale. Look at the cover and its lashings, the props ashore, the bilge, battery charge and, if afloat, the mooring lines.
Related Pages
Good SeamanshipMooring, anchoring, stormsRepair Guide100 findings and correct repairMarine Engine OverhaulDecision criteria and mistakesMarina GuideLifting and wintering regionsSurvey TypesCondition survey and scopesInterior & Joinery DefectsDamp, mould and stainingYacht InsuranceCover while laid up ashore
A condition survey before lay-up
She is already ashore, ideal conditions for moisture readings. If you plan to sell, rectifying out of season is the cheapest route.
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- Lay-up and refit: Combined in one plan.