5 ways to avoid canal boat breakdowns

To help you enjoy uninterrupted cruising, here are the top five causes of breakdowns and how to avoid them

1. Fuel issues and contamination

Diesel bug and water contamination still account for most fuel-related breakdowns. It’s an enzyme that lives off water in

diesel. In its mildest form it appears as black dust or soot, at worst it’s a black slime or jelly that clogs everything up.

Historically, the whole system would need to be cleaned, but additives that prevent the bacteria from growing and kill anything that may be forming in the tank are available for mild cases or as a preventative measure. More severe cases (or when the fuel system is blocked) require a diesel bug shock treatment. Blocked filters and fuel contamination due to dirt and debris from the tank also cause a large number of breakdowns – a situation that can be easily rectified through regular checking and servicing. A number of marinas now offer fuel polishing services which will clean fuel without having to treat or dispose of it.

2. Electrical

Mainly caused by lack of attention to electrical connections. Wires coming away or corroding is common, so look for loose connections or disconnected wires before you start and use a waterresistant spray or petroleum jelly to stop damp getting into electrical components such as isolators and block connectors.

3. Cables and linkages

For cables, this is primarily due to their exposure to the elements as most of the cable terminus is set outside. Cables have a certain lifespan which means they’ll rust if they’re not used regularly. To prevent this, grease the ends of the cable if leaving the boat for long periods and always check the operation before you set off; if there’s any roughness or stiffness, it might be time to call into a marina to pick up a new one.

When fitting, make sure that any bends are as minimal as possible because these will be the areas which suffer high stress and are likely to fail in the future. Tighten,

grease/replace linkages, where necessary.

4. Batteries

Misunderstandings are rife around what battery to use, electrical capacity and charging. For example, if you link a leisure rather than a cranking battery to your starter system you could be left without power when you need it most. The two types are designed for different requirements. The cranking battery is the same as fitted to most vehicles and designed to deliver a high output quickly, so it discharges and charges back to full capacity quickly.

A leisure battery is designed to deliver lower output continuously and, therefore, as long as it’s charged regularly will maintain capacity. As a general rule, assuming it is in good condition, each battery in your battery bank will require two to three hours’ charging to get back to full performance once fully discharged. If the wrong battery is used, the sudden surge of power needed to start the engine can quickly drain a leisure battery, leading to its failure.

Some ‘leisure’ batteries are modified starter batteries and their performance, while suitable for owners who use their boat sporadically, can prove unreliable for more frequent users. For liveaboard and frequent users it’s worthwhile investing in true leisure batteries.

Most people do not realise that each cell can affect the whole battery bank, and one of the best ways to prevent battery deterioration is to regularly check their level and top up using de-ionised water. If a cell’s water level drops to below 50 percent, it will affect the battery capacity and bring the whole bank’s capacity down to the same level, irrespective of how good the other batteries are. This is one of the best reasons never to mix and match batteries. Always replace the whole bank.

Don’t forget the battery terminals – keep them tight and greased. It only needs one loose one to cause engine failure and the main earthing cable (connected to the engine bed) is often the culprit.

5. Overheating and cooling systems

The most common cause is due to an airlock which is simple to identify and resolve. Feel the top and bottom of the swim tank; if everything is working fine there should be a difference in temperature, if not then both top and bottom will be either hot or cold. To remedy this, locate and unscrew the bolt on top of the ‘swim’ tank and this will release the air in the system.

However, overheating can be caused by many issues including a coolant hose rupturing (look for leaks), a water pump failing or an alternator belt (which drives the water pump) shredding or in the worst case, a head gasket failing.

Preventative maintenance

If you don’t understand the workings of your engine or fail to service and maintain it, it’s likely you’ll end up stranded at some stage. Lack of engine knowledge, gearbox /driveplate failures, alternator issues and faulty alternator belts, starters, propellers and couplings appear to be responsible for their fair share of call-outs. In the majority of cases the ‘emergency’ could have been avoided with a little ‘know-how’, by giving the boat a ‘onceover’ or simply carrying spares.

Know your engine – most owners believe the only way to turn off the engine when the switch fails (invariably causing a panic) is to turn off the fuel. However, most have a stop button or lever on the right-hand side of the engine, halfway down. Using this instead of the fuel shut-off allows you to restart and continue without having to bleed your fuel system.With Beta and Vetus engines a common issue is that the engine will not turn off or that the engine is ‘dead’. To resolve this, locate the wiring loom running across the top of the engine and identify a ‘bulge’. Peel back the rubber covering and you’ll find a block connector; just pull the two halves apart and then put it back together. This should rectify things. It’s easy when you know what to look for, so spend time looking at your engine before a failure occurs. If the engine is ‘dead’, it could also be the isolation switches. If they’ve been left ‘idle’ for a while it could be due to corrosion, so simply switch one way and then the other, or spray with WD40 (or similar) before you set off.

Bilges – if your bilges are full of oil and water it will end up being thrown over the engine, and if it gets into the engine, the consequences could be costly. As well as starters and alternators, it also tends to affect driveplates if the oil/water mixture gets into the bell housing.

Gearbox/driveplates – if you hit an underwater object, the driveplate is usually the first victim; however, if you do break the driveplate it’s unlikely you’ll damage the gearbox. General wear and tear appears to be another cause, and because canal boats don’t have a clutch like a car, gearboxes tend to receive a fair bit of abuse, so go easy and service them.

Alternators – contributing factors to failure range from poor batteries resulting in the alternator working harder to charge them, to battery management systems that overwork the alternator to keep batteries charged up. Ultimately, one of the biggest issues is that they operate in a damp, hot environment, which is not good for any electrical product. As with starters, they’re often left for long periods and then used continuously for short periods. During this ‘down period’, rust can develop and affect operation. There’s no way to prevent this other than to regularly visit the boat and run the engine. And remember, if a bilge is full of oil and water it will be thrown over the alternators which will bring about their early failure.

Alternator belts – always carry a spare, and before setting off check its (their) condition. Simply twist the belt and if there are cracks or the edges are starting to look ragged, it’s time for a new one. If you hear ‘squealing’ from an old belt, it’s usually an indication a replacement is needed. If it’s from a new belt, it needs adjusting. This is simple to do and worth knowing how to.

Couplings – if the bolts connecting the propeller shaft to the engine are loose, any movement will either shear them off, resulting in loss of propulsion, or make the bolt holes oblong, resulting in delayed drive. Eventually the coupling will need to be replaced, and you might even have to change your propshaft. A simple check before each journey will stop this happening.