There is a particular kind of November morning on the Hamble or the Clyde, when the wind has swung into the north-east and the pontoon is slick with frost, that reminds you how much a boat dislikes being left alone. Winterising needn't mean a yard bill running into four figures. With a little planning, a few cheap consumables and a handful of visits over the dark months, you can bring your boat through to April in far better shape than you left her.

Clean, dry and empty her out

Start with a thorough fresh-water wash down. Salt holds moisture against gelcoat, fittings and stainless steel, keeping surfaces damp long after the rain has stopped, so rinse the decks, coachroof and cockpit properly and let everything dry on a breezy day.

Then turn to the bilge. Pump it out, sponge the last of the water, wipe the residue away and leave the space genuinely dry — a wet bilge is the single biggest source of cabin condensation through the winter. Lift the cabin sole boards and prop locker lids open so air can move through the hull.

Strip the boat of anything that holds damp or feeds mould:

• Take cushions, mattresses and bedding home. Foam left aboard in an unheated cabin will grow mildew.
• Remove food, tea, coffee, paper charts, books and cardboard — all of it absorbs moisture.
• Drain the fresh-water tank and pipework, leave taps open, and flush sea toilets through with fresh water before draining them.

Stop water getting in

Before you cover anything up, hunt for leaks. Check hatch and window seals, chainplate and stanchion bases, cockpit locker lids and deck fittings. A tube of sealant or a roll of butyl tape costs very little and fixes most of them.

Clear every drain: cockpit scuppers, deck drains and their hoses. A blocked cockpit drain can fill the cockpit with rainwater and quietly flood a locker or the cabin through a dodgy seal. Work the seacocks while you're at it — a stiff one seized over winter is an expensive spring surprise.

Covers matter more than people think. A cheap tarpaulin stretched tight over the whole boat will trap condensation underneath it; a breathable cover, or a tarpaulin rigged with deliberate gaps for airflow, will do far more good. Keep the cover clear of sharp corners and make sure it can't collect water in pockets that then sag and pull.

Ventilation and moisture control

Cold doesn't kill boats — condensation does. Warm, damp air from a cabin left sealed tight will find every cold surface and leave it dripping by February.

Keep air moving. Leave dorade vents open, mushroom vents clear and, if you can, an opened hatch sheltered under a cover. A small solar vent is worth the money, but the budget route works well too:

• Chemical dehumidifier tubs placed in the saloon, forepeak and each cabin, emptied and refilled monthly.
• Cat litter or coarse rock salt in an open bucket or tray, which does much the same job for pennies.
• Silica gel sachets in the toolbox and in lockers holding anything metal.

Don't block the vents with gear, and leave internal doors and locker lids open so air circulates everywhere. Be wary of unattended electric heaters — many insurers and marinas take a dim view for good reason. A low-wattage tube heater on a thermostat is the safest compromise if you have shore power; a fan heater left running on an empty boat is not.

Engine, fuel and batteries

Change the engine oil and filter before laying up rather than after. Used oil carries acids and combustion by-products that quietly attack bearings over the winter, and fresh oil is a cheap insurance policy.

Test the coolant with a hydrometer and top up to the correct concentration for the frosts you expect. Don't mix coolant types — organic and inorganic formulations dislike each other. Fill the fuel tank almost to the top to reduce the air space where condensation forms, add a fuel stabiliser, and drain any water from the separator. Run fresh water through the raw-water side of the cooling system and drain it, or draw antifreeze through it if the boat stays afloat in freezing conditions. Close the seacocks.

Batteries respond well to a little kindness. Charge them fully, disconnect the terminals, and either take them home to a frost-free spot or leave a solar trickle charger aboard. Recharge every six to eight weeks, and smear the terminals with petroleum jelly before you reconnect.

Sails, canvas and ropes

Sails should come off the boat. Wash them in fresh water, dry them thoroughly on a calm, dry day, fold them loosely and store them in a breathable bag somewhere dry — not in a damp garage or against a concrete wall, and ideally somewhere mice can't reach.

Running rigging benefits from the same treatment. Ropes can be washed in a pillowcase on a cool, gentle cycle with a little mild detergent, then air-dried out of direct sun and coiled loosely. Wash and reproof sprayhoods and sail covers, storing them indoors if you possibly can. If a boom cover stays on, check it breathes and doesn't funnel rainwater into a pocket. Finish by servicing winches, blocks and travellers with a light grease so they're ready in spring.

Winter visits and mooring checks

Plan to visit roughly monthly. Check mooring lines for chafe, add a spring line for security, and adjust warps as temperatures drop and ropes tighten. Brush snow off covers before it gets heavy enough to distort a frame or a canopy, and pump the bilge if any water has found its way in.

Have a quick look at your insurance policy for any lay-up conditions — some require notification or a minimum attendance. Keep a note of what you've done and when. A boat that is checked, aired and kept dry over winter rewards you with a spring launch that needs cleaning, not repairing.