How to winterise your narrowboat

Published: 04:07PM Oct 12th, 2011
By: Towergate Insurance Marine

WITH winters getting colder each year and sub-zero temperatures becoming more common across the UK, narrowboat insurance provider, Towergate Insurance Marine has put together some hints and tips on how to winterise your narrowboat and so avoid costly repair bills.

How to winterise your narrowboat

For those living on their narrowboats it’s pretty much business as usual, although extra attention should be given to topping up antifreeze in keel cooling and other sealed water systems (such as radiators connected to the boiler).   Lagging hot and cold pipes is also a good idea.

However, if your narrowboat is being laid up for the winter, the ‘to do’ list is somewhat longer; 

Engine and gear casing

To keep water out of the engine and gear casing, fill the diesel tank to prevent condensation and add the correct ratio of fuel conditioner (available from most chandleries).

Used regularly, fuel conditioner increases performance, reduces emissions and improves fuel economy. It also removes water from fuel lines and tanks, prevents and dissolves fungal growth, dissolves deposits from the fuel system, injectors and carburettors and de-carbonises combustion chambers. 

If you’re nervous about leaving a full tank of diesel idle over the winter, as it may be a tempting target for thieves, ensure your engine has a water filter - this’ll keep water out of the fuel line.

There are two types of diesel engine; air cooled and water cooled. Air cooled engines will not suffer ice problems, however water cooled ones will if not properly treated. Ensure the right amount of anti-freeze is in the water cooling system (if closed or keel cooling). If you have a raw water system, seal off the cock valve and if the engine is not to be used, drain the water out of the cooling jacket.

And don’t forget to change the oil filters in the spring when the engine is serviced.

Spray terminals with a silicone-free lubricant and grease all available grease points on the engine and drive, plus electrical connectors. Also lubricate linkages and gear/throttle slides.

Grease the stern tube once the engine is off – a vital link between propeller and engine. If not greased, water may dribble into the engine room, which over a long period of time can build up and cause your narrowboat to sink. As the boat gets lower in the water, any outlets such as those for a shower, sink or air vent, will get nearer to the water level and the result can be catastrophic. Grease the stern tube every time you turn off the engine as once the propeller turns, the seal is broken.

It’s also a good idea to run the engine for an hour every month- this pushes oil around the engine and prevents rusting, plus it tops up the battery if left running long enough.


If not in use, store in a gas-tight locker – the same regulations as Liquid Petroleum Gas (LPG) apply here.

Water and heating

Burst water pipes can be a nightmare – yet easily avoided with some simple precautions;

Lag your hot and cold pipes and top up anti-freeze in keel cooling and other sealed heating systems (such as radiators connected to the boiler). This point is being repeated because it’s the single most important thing to do, whether your narrowboat is being used over the winter period or not.    

Drain down the water system (including drinking water and cistern) and leave taps in the open position. Most water heaters have a screw plug at their base and most can accommodate an old-fashioned cycle pump which makes the emptying of water that much quicker.

Taps should be left open because if any water is left in the system and it freezes, the pressure on the pipes will be less due to air coming out of the taps.

Protecting possessions

Remove valuable items such as electricals, the television, even booze. If you have the luxury of a secure mooring this might not be such an issue, but if in doubt – take it out.

Invest in a decent lock – the chances are this will deter a thief and your insurance policy requires this. There are alarms on the market that generate a text to your mobile if activated, however, the general consensus appears they are costly and have limited effect.

Mushroom vents are becoming increasing popular amongst thieves so check your covers for water/gas heater exhausts or air ventilators have a bar across the bottom of their thread – this ensures they’re difficult to screw out.

Deter solar panel pilferers by using a marine-grade UV bonding compound that sets in 24 hours and is rock solid. Use it for the panels themselves or to glue the feet of mounting kits that house glass panels– a less intrusive option than welding or drilling holes.

Flexible panels can also be screwed onto a flat surface or clipped onto a narrowboat. Rather than using conventional nuts with bolts, use security shear nuts, whereby the nut is tightened to a certain torque and then the top section twists off leaving a tamper-proof cone. If you have glass panels, they’re more at risk of vandalism than plastic ones.

There’s much debate over whether adhesive or shear nuts are the best option for securing solar panels. If you use marine-grade adhesive on the panel itself and not the mounting feet, it will be difficult to maintain the roof below and once stuck down, the panel is there for life, making it difficult to repair or replace. Shear nuts, however, can be removed with a fair bit of effort.

To avoid discolouration, you may want to put grease on your external brass, as some narrowboat owners do.

Put away any spare ropes.

Diesel regulations

Although not crucial to winterising your narrowboat, it’s important to keep abreast of changes in legislation. From 1 January 2011 the Fuel Quality Directive 2009/30/EC is in force. This stipulates that non-road machinery gas oil must contain no more than 10mm sulphur and applies to inland waterway vessels and recreational craft when not at sea.

Suppliers are likely to provide road diesel with a red marker dye which contains up to 7% biodiesel. One of the UK’s largest narrowboat and canal boat marinas, Trinity Marinas, says that because biodiesel is a solvent, it has concerns over the increased risk of bacterial contamination, including the oxidisation and precipitation of solids. To combat this, Leicestershire-based Trinity recommends a six month fuel turnover and reminds vessel owners to check the compatibility of this diesel with the fuel seals on older engines, fuel hoses and copper fuel lines. 

If you have an older vessel Trinity suggests replacing the fuel seals and fuel hoses as a precaution, examining the fuel systems after you’ve switched and replacing fuel filters after using two to three tanks of fuel. 

Frequent checks of tanks will minimise water contamination, as will using a diesel bug treatment to break down the slimes and dead organisms (bacteria and fungi can enter the tank from the atmosphere via the vent or filling point).

Ask the experts

Thanks to Towergate Insurance Marine’s inland waterways expert and narrowboat owner Michael Stimpson and to the team at Trinity Marinas for their help with the hints and tips.

For risk management and insurance advice phone 0800 515629 or visit and click on Boat.

For anything else to do with narrowboats call 01455 896820 or visit

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