With the winter drawing in, thoughts begin to turn to next summer’s boating—but it’s worth putting in some effort now to make sure your boat makes it through the winter in great condition. 

No matter your boat, whether sail, power, narrowboat, speedboat, RIB or jet ski, there are steps you can take to ensure it withstands whatever winter throws at it. Follow our quick guide to winterising a boat for everything you need to know. 


1. Winterise the engine

Winterising a boat engine is a must. If the boat is laid up ashore, you can change the oil, check that the coolant is topped up or, in the case of raw-water cooled engines, flush it with fresh water before running some antifreeze through.

For boats left afloat in salt water, it’s unlikely that the temperatures will dip low enough to cause any saltwater left in the engine to freeze. Still, it’s worth attending to if a particularly cold snap is forecast.

Make sure the fuel tank is topped up, reducing the condensation that can form in the tank and lead to diesel bug. Better still, add a fuel additive to kill and protect against diesel bug.

Related: Top 10 must-have boat gadgets and accessories


2. Drain the water systems

The next step to winterising your boat is draining down all fresh-water systems to prevent freezing, including water tanks and calorifiers. 

It’s also a good time to flush them with a mild chlorine solution and rinse them well to keep them clean and slime-free for next season. Leave your taps open to allow any water that does freeze to expand and escape without damaging the fittings.

For larger boats with outside water systems (for instance, wash-down hoses and transom-mounted showers), it’s especially important to drain these down to avoid frost and ice damage.


3. Remove the sails and service the rigging

winterising your boat

If your mast is staying up, take headsails off their furlers and mainsails off the boom—high winds and exposure to extreme weather can damage them.

They also add unnecessary windage, which can be hazardous if the boat is stored ashore. Think about any sail repairs early in the winter, while the sailmakers are quiet—don’t leave it until the spring, when they will be snowed under with work.

If your mast is to come down, lubricate the rig’s bottlescrews to help the yard when they remove it and take off wind instruments and VHF antennas to stop them from being damaged. Coil halyards neatly at the base of the mast.

Related: How to winterise your rigging


4. Prepare the boat’s interior

If you’re not using the boat during the colder months, take cushions home to keep them dry and mildew-free. If you must leave them on board, prop them up on their side to allow air to circulate.

Wash out the bilges with detergent and fresh water and sponge them out again. This removes salt that will retain moisture and keep the inside of the boat damp all winter.

A dehumidifier will keep the interior fresh—but make sure it can drain overboard and is wired up via an RCD-protected supply to avoid fires. A greenhouse-style heater is another option to keep the temperature above freezing for minimal power usage.


5. Clean and lubricate the seacocks

Seacocks work as a valve to allow water into the boat to cool the engine. So, if they aren’t functioning properly, they can lead to water ingress.

An important step to preparing your boat for winter is to flush your seacocks with fresh water and lubricate the moving parts to prevent them from seizing up over the winter and causing you issues next season.

Related: How to keep seacocks working smoothly


6. Store your boat carefully

winterising your boat

This is one of the most important decisions you’ll make when winterising a boat. Ideally, you’ll store it out of the water and undercover in a secure location, such as your own property or a marina. 

If the boat is on a pontoon, add extra fenders and lines, and consider adding rubber snubbers to the mooring lines if the boat is in an exposed berth.

We know this isn’t always possible, but you should ensure you keep it covered with quality tarpaulin at the very least to protect it from the elements. 

Don’t forget to check your insurance policy to ensure you’re covered, whether the boat is hauled out ashore or still afloat. 


7. Remove all valuables

Even if your mooring is secure, it’s worth taking any expensive electronic and navigational equipment home with you to store in a safe place.

This is an important step when learning how to winterise a boat, yet it’s commonly overlooked. If you don’t remove valuables from your boat when left unattended, they’re unlikely to be covered under any insurance policy. 


8. Invest in a winter cover

Investing in a good winter cover is another of the most important steps to winterising a boat. It will mean you will have much less work to do in the spring to bring the boat back into commission—she will be clean, dry, and ready to go. 

Shrink wrapping is a one-use option, or you can get a custom-made cover that you’ll be able to use year after year.


Specialist insurance with Insure4Boats 

Alongside winterising your boat, you may want to protect it through specialist boat insurance to ensure it’s covered in the worst-case scenarios. 

With Insure4Boats, the Boat (Hull & Machinery) cover protects your boat against theft, damage, and salvage charges. 

Third-Party Liability cover is included as standard and protects you if you injure another person or damage another boat or third-party property whilst out on the water. 

Click here to learn more about how we can help, or get an instant online quote today. 


Please note the information provided on this page should not be taken as advice and has been written as a matter of opinion. For more on insurance cover and policy wording, see our homepage.