How to winterise a boat in the UK
By Mark Bonnett, founder of Marine Match and owner of a 1980 offshore race boat · Last updated
Winterising a boat means protecting the engine, water systems and batteries from frost and damp before the boat sits unused over winter. In the UK it's usually done between October and November, after your last trip and before the first hard frost. Most owners have the engine side done by a marine engineer and handle cleaning and covers themselves.
When should I winterise my boat in the UK?
Winterise as soon as you've finished using the boat for the season, and in any case before the first frost, which in much of southern England can come from late October. Engines and water systems are at risk from the first night below freezing. If you're lifting out, do the engine work just before or just after the lift, while you can still run the engine.
What does a professional winterisation include?
A typical engine winterisation covers:
- Changing the engine oil and filter while the engine is warm, so acidic old oil doesn't sit in the engine all winter
- Flushing the raw-water cooling system and filling it with antifreeze
- Removing and inspecting the raw-water pump impeller
- Treating the fuel with stabiliser and filling the tank to reduce condensation (petrol engines are also fogged)
- Checking anodes, belts, hoses and the gearbox or outdrive oil
Around the rest of the boat:
- Draining the fresh water system and water heater, and adding non-toxic antifreeze where needed
- Flushing and treating the heads and holding tank
- Charging the batteries, then disconnecting them or leaving them on a smart charger
- Taking off sails and canvas to be cleaned and dried, and fitting a ventilated cover
- Cleaning and drying the bilges
How much does boat winterisation cost in the UK?
As a rough guide (October 2026), professional engine winterisation typically costs:
- Outboard engine: around £150 to £350
- Single inboard diesel: around £250 to £500
- Twin engines: roughly double
Prices vary with engine size, access, parts needed and whether the engineer comes to you. Lift-out, pressure wash and storage ashore are usually charged separately by the marina or yard. The best way to know is to compare quotes for your own boat.
Is it worth getting a boat professionally winterised?
For most owners, yes, at least for the engine. A cracked block, heat exchanger or water pump from one frost can cost far more than a winterisation, and getting it wrong is easy if you don't know your engine. A professional job also leaves a record you can show a buyer, surveyor or insurer. If you're confident with your engine, doing it yourself is fine, but log what you did and when.
What happens if I don't winterise my boat?
Water left in the engine, pipework or water heater can freeze, expand and crack metal parts. Damp and stale fuel cause starting problems in spring, and batteries left flat over winter often don't recover. Some insurance policies won't pay for frost damage if reasonable precautions weren't taken, so check yours.
Should I leave my boat in the water or ashore over winter?
Ashore keeps the hull dry and makes spring jobs like antifouling easy, but costs more in lift and storage fees. Afloat is cheaper and lets you use the boat on good days, but needs regular checks on bilges, mooring lines and batteries. Either way, the engine and water systems still need winterising.
Jet skis and outboards
Jet skis and outboards need winterising too: flush with fresh water, fog the engine, stabilise the fuel, and charge or remove the battery. They're quick jobs for a mobile engineer.
Book your winterisation and keep the record
On Marine Match you can book a marine professional directly or get up to three quotes. Payment is held until you sign the job off. When a Verified professional does the work, it's stamped on your boat's free Boat Passport, so next spring, and when you sell, the history is there.
Frequently asked questions
- When should I winterise my boat in the UK?
- As soon as you've finished using the boat for the season, and before the first frost, which in much of southern England can come from late October. If you're lifting out, do the engine work just before or just after the lift, while you can still run the engine.
- How much does boat winterisation cost in the UK?
- As a rough guide (October 2026), professional engine winterisation costs around £150 to £350 for an outboard and around £250 to £500 for a single inboard diesel; twin engines cost roughly double. Lift-out, pressure wash and storage ashore are usually charged separately.
- Is it worth getting a boat professionally winterised?
- For most owners, yes, at least for the engine. A cracked block, heat exchanger or water pump from one frost can cost far more than a winterisation, and a professional job leaves a record you can show a buyer, surveyor or insurer.
- What happens if I don't winterise my boat?
- Water left in the engine, pipework or water heater can freeze, expand and crack metal parts, and batteries left flat over winter often don't recover. Some insurance policies won't pay for frost damage if reasonable precautions weren't taken, so check yours.