Why Winterising Matters on the Cut

There is nothing quite like a crisp morning on the canal, with frost on the towpath and a curl of smoke from the stove. But as beautiful as winter can be, it is also the season that catches out unprepared boaters. Water left in pipes expands as it freezes, and that expansion is strong enough to split copper, crack plastic fittings and ruin a water pump. Engines suffer too, particularly if the cooling system is not protected. Then there is the damp — the quiet enemy of every narrowboat interior, creeping into cushions, cupboards and woodwork while you are away.

The good news is that winterising a canal boat is straightforward, inexpensive and deeply satisfying once it is done. Set aside a weekend in late October or early November, before the first hard frost, and work through the list below. Your boat will thank you in March.

Drain Down the Fresh Water System

This is the single most important job, and the one most commonly skipped. If you leave the boat for more than a few days in freezing weather, drain the system properly.

• Turn off the water pump at the isolator switch and open every tap — galley, bathroom, shower — to release pressure.
• Drain the water tank. Many narrowboats have a drain cock near the tank outlet; if not, run the taps until the tank is empty.
• Open the drain valve on the calorifier (the hot water cylinder) and let it empty. This is where a surprising amount of water hides.
• Disconnect the shower mixer and any flexible hoses, tipping out the residue.
• Blow compressed air through the pipework if you can, or use a purpose-made plumbing antifreeze for the traps and toilet. Never put automotive antifreeze into the fresh water system.
• Leave all taps open so any remaining water has room to expand.

If you live aboard through the winter, you can leave the water system in use, but keep the cabin above freezing and consider a small greenhouse heater or tube heater in the engine bay and near the calorifier.

Protect the Engine and Cooling System

An engine that has not been winterised can suffer a cracked block, and that is an expensive repair. Check your antifreeze strength with a hydrometer — it should protect down to around minus 25°C, and most marine coolants should be replaced every two to three years regardless.

• Change the engine oil and filter before lay-up. Old oil contains acids that attack bearings over winter.
• Top up the gearbox oil and check the stern gland, greasing it well if it is the traditional type.
• Fill the fuel tank to reduce condensation, and add a diesel biocide to prevent bug growth.
• Remove the impeller if you are laying up for months, or at least inspect it.
• Take out the batteries if you can, store them somewhere frost-free and give them a charge every six weeks. Otherwise, leave them aboard on a smart charger or solar maintainer.
• Grease all exposed electrical connections and spray terminals with a protective compound.

Keep the Cabin Dry and the Stove Sweet

Damp does more long-term damage to a narrowboat than cold ever will. Ventilation is your friend: air needs to move through the boat even when you are away.

• Leave interior doors and cupboard doors open so air circulates.
• Fit ventilators or leave a couple of windows on the security setting.
• Use moisture absorbers in wardrobes and under bunks, and check them monthly.
• Lift mattresses and cushions off the bases so air can reach underneath.

If you have a solid fuel stove, this is the moment to service it. Sweep the flue, check the firebricks and rope seals, and clear the ash pan. A stove that has been left with damp ash will corrode from the inside out. Close the damper to stop draughts, but do not seal the flue completely — a little airflow prevents condensation inside the chimney.

Exterior Checks and Mooring Security

Winter weather on exposed stretches of canal can be fierce. Walk the boat from bow to stern and look for anything that might suffer.

• Check fenders, ropes and mooring pins. Replace any frayed lines before the gales arrive.
• Clear the roof of leaves and debris so water drains freely, and check scuppers are not blocked.
• Inspect the cratch cover and pram hood for tears; patch or reproof as needed.
• Grease the paddles and lockers, and oil exposed hinges.
• If you are leaving the boat unattended, tell a neighbouring boater or your mooring warden so someone can check on it.

Do not forget the water tank filler and pump-out connections, which can freeze solid if left exposed.

A Winter Well Spent

Winterising is not just about avoiding damage — it is about being ready to enjoy the quietest, most atmospheric months on the waterways. A boat that has been properly drained, serviced and ventilated will come through the cold without complaint, and you can spend the dark evenings beside a well-behaved stove rather than mopping up a burst pipe.

Work through the list methodically, keep a note of what you did and when, and check on the boat regularly if you are not living aboard. Come spring, you will be cruising within days while others are still chasing leaks and replacing impellers. That is the reward for a job done properly in the autumn.