Winter on a Mooring: A Different Kind of Maintenance

Come November, many UK boat owners breathe a sigh of relief, tie up on the mooring and head for the fireside. But a boat left afloat through winter faces a unique set of pressures: driving rain, salt spray, gales, frost and the constant movement of tide and swell. Unlike a boat in a marina berth, a mooring offers little shelter and no shore power. The good news is that a few regular, practical checks will protect your investment and have you ready for an early spring launch. The key is to visit often, think ahead, and treat the winter as a season of maintenance rather than abandonment.

Mooring Lines, Shackles and Chafe Protection

Your mooring tackle is the first line of defence, so inspect it before the worst weather arrives. Double up your lines wherever possible – a second warp or a heavier nylon line gives you redundancy if one chafes through. Nylon is ideal because it stretches under load, absorbing shock from wind and waves, but it also wears quickly where it rubs against fairleads or the bow roller.

• Check every shackle and swivel. Look for cracks, excessive wear or missing mousing wire. Seize shackles with stainless wire or heavy cable ties so they cannot work loose.
• Add anti-chafe gear. Slide plastic or leather sleeves over lines where they pass through chocks or over the toe rail. Even a length of old hose can save a warp.
• Inspect the buoy and chain. If you can lift the buoy, check the shackle and swivel below it. If the chain looks thin or rusty, report it to your mooring officer – winter is not the time to gamble.
• Allow for tide and surge. On a swinging mooring, ensure the boat can swing freely without snagging other craft. Leave enough scope for spring tides and storm surge, but not so much that she ranges too far.

After every gale, walk the lines again. Chafe can happen in hours, not weeks.

Covers, Ventilation and Keeping the Rain Out

A good winter cover is not just about keeping rain off; it is about letting damp air escape. Non-breathable tarpaulins trap condensation, which drips onto woodwork and encourages mould. Choose a breathable cover or a purpose-made winter cover with a ridge pole or frame so that water cannot pool. Pooling water is heavy, stretches the fabric and eventually finds a way inside.

Ventilation is equally important. Leave lockers and cabin doors ajar to allow air to circulate. Fit dorade vents or simply crack a hatch on the leeward side, protected by a cover. Use moisture absorbers in lockers and under cushions, and check them monthly. If you can, lift cushions and sails off the sole so air can move underneath. A dry boat is a happy boat, and it will smell far better in March.

Bilge Pumps, Batteries and the Damp Battle

Water in the bilge is your enemy in winter. It can freeze, expand and crack the hull or seacocks. It also raises humidity throughout the boat. Test your automatic bilge pump and float switch regularly – a stuck switch is a common cause of winter flooding. If you have a manual pump, make sure it works and that the handle is stowed where you can find it in a hurry.

• Keep the bilge dry. Check cockpit drains and anchor locker drains for blockages. A small electric pump on a timer or a solar-powered trickle charger can keep a battery topped up for the automatic pump.
• Battery care. Remove batteries if possible and store them ashore in a cool, dry place. If they stay aboard, charge them fully and then connect a smart trickle charger or a small solar panel. Never let a battery sit flat – frost will kill it.
• Check wiring and connections. Corrosion loves damp, salty air. A squirt of dielectric grease on terminals helps. Look for chafed wires before they short.

Visit after heavy rain to pump out any water that has found its way in. It takes ten minutes and can save thousands.

Winterising the Engine and Fuel System

Frost damage and corrosion are the two big killers of marine engines left afloat. Start by flushing the raw-water system with fresh water, then drain it completely. If you have a closed cooling system, check the antifreeze strength with a hydrometer – it should be good for at least -15°C. For raw-water cooled engines, run antifreeze through the system until it exits the exhaust.

Change the oil and filter before lay-up; old oil contains acids that attack bearings over winter. Fog the cylinders with storage oil, turn the engine over briefly, and seal the air intake and exhaust with tape to stop damp air entering. Fill the fuel tank to the brim to reduce condensation, and add a fuel stabiliser. Close all seacocks and label them. For outboards, store them upright, drain the carburettor and grease the pivot points. Anodes should be checked and replaced if more than half wasted.

Removing Valuables and Preparing for Storms

Anything you would miss if it disappeared should come ashore. That means electronics, charts, binoculars, flares, cushions, bedding, paperwork, outboard motors and fuel cans. Thieves are active in winter, and a boat on a mooring is an easy target. Lock the cabin and leave a light on a timer if you can.

On deck, remove or lash down anything that can flap or blow away: fenders, buckets, boat hooks, sail covers. Secure halyards so they cannot slap all night – a quick wrap around the mast or a bungee will do. Finally, tell a trusted neighbour on the mooring that you are away, and swap phone numbers. After a storm, a quick check by someone local can catch a chafed line or a risen bilge before it becomes a disaster.

Winter maintenance is not glamorous, but it is the difference between a boat that launches smoothly in April and one that needs a yard bill. A little time now pays you back with interest.