How to winterise your boat: a checklist
Updated October 2026
Your boat should be ready for winter before the first frost. Here are the jobs in the order you do them, and what is worth writing down as you go, so spring is easier.
Before the boat comes out
- Empty the holding tank while the boat is still in the water.
- Check that the cradle, trailer or stands are in good order before the lift.
The engine
- Outboard: run it in fresh water to flush salt and dirt out of the cooling system.
- Inboard: run antifreeze through the raw-water side of the cooling system, so nothing freezes and cracks.
- Change the oil and filter while the engine is warm — the old oil drains more easily — and fill with fresh oil, which protects against corrosion over the winter.
- Always follow the engine manufacturer's instructions for your engine.
Fresh water
- Drain the freshwater tank, water heater, pipes, pumps and shower hoses completely.
- Leave the taps open over the winter.
The battery
- Charge the battery fully. A fully charged battery can take frost; a flat one can freeze.
- Ideally take it out and store it somewhere frost-free, preferably on a maintenance charger.
The cover
- Cover the boat with a tarpaulin tight enough for snow and water to run off, but ventilated, so condensation doesn't build up underneath.
More guides
How to close your cabin for winter: a checklist
Winter tyres in Norway, Sweden, Denmark and Iceland: dates and rules