A simple guide to winter boat maintenance

A simple guide to winter boat maintenance

As the weather cools, you will probably be spending much less time on the water: perhaps not even venturing out at all. Either way, it is likely your boat will be sitting idle during the worst weather of the year.  While you might not be using it, it is still important to ensure it remains in good condition throughout.
Boats left exposed to rain, wind, ice and snow can suffer serious damage, meaning you may have to spend time and money putting it right again. Protecting your vessel properly during winter will help to prevent major repairs the following spring.
To help you, we’ve put together a handy checklist to help your boat survive the cold season:

In or out?

The majority of this advice applies to boats either left in, or stored out of the water over the winter. However, if you are able to keep your boat on land for the duration, use it as an opportunity to check over the parts that are normally underwater, or difficult to get to. This prevents moss and algae building up and allows you to see any areas which may need attention.



Both the exterior and the interior of your boat need a thorough clean before it is ready to be covered up. A pressure wash to the outside, including the decks, will remove salt residue. A wax coating to the exterior after cleaning protects exposed parts against bad weather.
Soft furnishings can pick up mildew if they become damp. Remove them from the boat where possible and keep them at home, to prevent this.
If you don’t have the room to store them elsewhere, stand them up separately so air can circulate.
Boats that are kept shut up over the winter are at risk of mould from moisture build-up.  The more ventilation you can provide the interior with, the better.
Leave doors and drawers open to let the air flow through them. If you can set a heater/dehumidifier on a timer throughout the period your boat is inactive, even better. Moisture absorbers can also be left onboard if you will not have access to power during storage.


The cold can damage unused batteries, so take them out, and store them somewhere dry. Give them a clean and oil the terminals before you put them away.
They’ll need to be fully charged, or topped up, once a month or so. If left uncharged the whole time your boat is unused, you will probably need to replace them before setting out on the water again.
If you cannot remove the batteries, keep them full and regularly charged to prevent freezing if the temperature drops. Make sure they are disconnected from the electrical system before leaving them. You can also lay sheets of cardboard underneath them, for extra insulation.


Give the engine a service, checking it over thoroughly. If there are any areas that need a bit of TLC, get them sorted now. Change the oil, and put in a new filter, then take a look at the gearbox or outdrive oil. If it looks murky, it’s time to change that too.

Drain the cooling system, and refil with fresh water and anti-freeze. Start the engine and let it run, to ensure the anti-freeze has passed through the entire system. This stops the insides of the system corroding, as well.
Take out the air intake filter, and stuff an oily rag into the intake, to prevent interior rusting.

Finally, give the whole engine a clean, and spray it with WD-40, particularly the wiring and electrics, to keep the damp out. 

Drive belts

If the boat is not used for several months, the drive belts will remain in the same position. This could lead to warping or cracking. Either remove the belts, or relax them, for the time the boat is unused. The pulleys should be cleaned and oiled, so rust is kept at bay.


If your boat is going to be left for long periods of time then draining the whole tank makes it less of a fire risk.
If draining is not an option, fill the tank almost full. Leave a small gap left to allow for fuel expansion during warmer temperatures. A full tank stops the vent from drawing in damp air, and leaving condensation inside, which could corrode the tank. You could consider adding a stabiliser to the fuel, as well, to stop it oxidising and causing problems later.

Apply petroleum jelly to the fuel-filler cap lid. This will give it a temporary seal and stop rainwater getting inside.

Clear the bilges

Water left sitting in your boat’s bilges over the winter can cause problems, so make sure they are completely drained, cleaned and scrubbed. 

It can be useful to paint the bilges a light colour, while you are at it. This will enable you to spot any future leaks as they happen.

Cover it up

An abrasive tarpaulin slamming into your boat during high winds can severely damage the outer surface.
A layer of padding or blankets before the tarpaulin goes on prevents scratching. It will also stop sharp edges from wearing through the tarpaulin. You can also get canvas covers custom-made to fit your boat, or consider shrink wrapping. The latter can be time-consuming but shrink wrap is close-fitting (preventing anything banging against the boat’s surface), durable and excellent at protecting impractical shapes. It cannot be redeployed once it’s been removed, however, making it a more expensive option than a reusable cover.
Ensure whichever cover you choose has adequate venting, to stop condensation, which causes mildew to grow.

Once covered, angle your boat upwards from the bow end, to allow rain to run off.
You should still keep an eye on your boat, especially in stormy weather. Heavy snow, wind or rain, combined with debris such as fallen leaves, can sometimes defeat even the strongest of coverings, so regular checks will catch problems before they’ve done too much harm.

Check your boat regularly

The tips above will give your boat the best chance of making it through the winter unscathed, but that doesn’t mean you should forget about it until the spring. Habitual checks will flag up any problems which occur while it is hibernating.

Look over the cover for tears, or anywhere water is pooling. Air the cabin for as long as possible and give the boat a general once-over.

Then, when spring arrives again, your boat should be as ready as you are to get back out on the water!
Looking to buy a boat? Take a look at our boats for sale. If you are thinking about selling your boat, check out our advertising packages. For any other enquiries, please contact us.


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