Winter has a rhythm all of its own

A narrowboat sitting quietly from November to March is rarely damaged by the cold alone. Frost, damp and neglect do the harm together, and the difference between a boat that comes through the winter in good order and one that needs a new water pump, a replacement run of pipework and a fortnight of scrubbing is usually a few hours of preparation in late October. The work is unglamorous, but it is the cheapest insurance you will ever buy.

If you are staying aboard through the winter on a residential mooring the routine is rather different from laying the boat up. This is aimed mostly at the laid-up boat, with notes for those who stay.

Drain down the domestic water system

Start with water, because frost finds pipework long before it finds anything else. Turn the pump off at the isolator, open every tap — hot and cold — then drain from the lowest point in the system. Open the drain cock on the calorifier, or disconnect the lowest union and let it empty into the bilge, then mop the bilge dry.

• Empty the fresh water tank completely. A part-filled tank offers ice plenty of room to work on the seams and fittings.
• Drain the calorifier fully. If it is fed from the engine cooling circuit, that side needs attention too — see below.
• Flush and drain the toilet. Cassette and pump-out tanks should be emptied before the cold sets in, and a cupful of non-toxic antifreeze left in the bowl seal.
• Dose every trap — sink, basin, shower tray — with a good cupful of propylene glycol antifreeze. Never use the toxic ethylene glycol type where it might reach the watercourse.
• Remove the water filter cartridge if you have one, and drain the accumulator and any inline pressure vessel.
• Leave the taps in the open position so any residual water has somewhere to go.

Engine, batteries and the cooling circuit

Check the engine coolant with a hydrometer and bring it up to a 50/50 mix if it has weakened. Skin tanks and keel coolers should not be forgotten, but the domestic and engine side of the calorifier is where a surprising amount of damage happens.

Batteries hate a slow death by sulphation more than they hate cold. Charge them fully, then either remove them to a dry shed or leave them connected to a smart charger on a low maintenance setting. A plugged-in boat with a 240V hook-up makes this easy; without one, take the batteries home and charge them once a month. Top up the fuel tank rather than leaving it half empty — a full tank has far less room for condensation — and change the oil and filter before lay-up so the engine sits in clean lubricant rather than acidic by-products.

A tube heater of 40 to 60 watts, or a small greenhouse heater, left running in the engine bay on a thermostat will keep the frost off without costing much to run.

Bilges, pumps and the hull

Clean the bilges before you leave. A layer of grit, leaves and rust flakes is exactly what jams a float switch at the moment you need it. Once the bilge is dry, lift the float on any automatic pump by hand and listen for it starting. Check that the discharge outlet and skin fitting are clear of debris and that water can actually leave the boat.

• Confirm the weed hatch is properly sealed and the retaining bar is tight.
• Give the stern gland greaser a couple of turns, and check for drips you would not want to come back to in February.
• Inspect the anodes while the water is still clear enough to see them, and note anything more than half wasted.
• Check the cratch and pram hood for split seams — a winter of wind will finish them off.

Insulate pipes, ventilate and fight the damp

Lag every run of pipe you can reach, especially along the hull sides where the cold bites hardest. Foam sleeving on the hot and cold runs, and a length of lagging wrapped around the outside tap and the shower mixer, will save you a springtime of mopping.

Ventilation matters as much as insulation. Seal a boat up completely and condensation will form on every cold steel surface, running down the walls and into the bedding. Leave mushroom vents open, keep side vents clear, and prop cupboard doors open so air can circulate. In a marina with a hook-up, an oil-filled radiator on a low stat paired with a dehumidifier plumbed to drain into the sink will keep the interior dry. If you have no power, a couple of moisture traps and open vents are the honest answer.

Regular visits and the mooring lines

Visit every two to three weeks, more often if you can. On each visit, look for three things: water in the bilge, mould on the lining and a change in the boat's position. Winter levels move a great deal, and a line that was snug in October can be bar-tight by January, pulling the mooring pins or chafing through against a fairlead. Leave sensible slack, fit spring lines, and wrap any point of contact with a length of old hose or leather.

Use your visits to run the engine for twenty minutes, check the charger is doing its job, and air the cabin. Keep a small notebook or a note on your phone: date, bilge condition, battery voltage, anything that needs doing. Come spring, you will know exactly where to start — and your boat will thank you for it.