Lack of engine knowledge, gearbox /drive plate failures and faulty fan-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 'once-over' or simply carrying spares.
River Canal Rescue runs monthly Engine Maintenance courses providing 'hands on' experience in dealing with common issues and how to service your engine. Check their website for dates.
Know your engine - common issues
Most owners believe the only way to turn off a boat's engine when the switch fails (invariably causing a panic) is to turn off the fuel. However, most vessels have a manual stop button or lever located on the right hand side of the engine, half-way down. Using this instead of the fuel shut off will allow you to restart and continue on your journey 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 completely 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 will find a block connector - just pull the connection block apart and then put it back together. This should rectify the situation. It's easy when you know what to look for, so spend time scrutinising your engine before a failure occurs.
In contrast, if the engine is 'dead', it could be the isolation switches. If they've been left 'idle' for a while, it could be due to a corrosive build-up, simply switch one way and then the other, or spray with WD40 before you set off.
Bilges - as mentioned earlier, if your bilges are full of oil and water, this will end up being thrown over the engine - and if it gets into the engine, the consequences could be disastrous (it's also not a nice place for engineers to work). As well as starters and alternators, it also tends to affect drive plates if the oil/water mixture gets into the bell housing.
Gearbox/Drive Plates - If you hit an underwater object, the drive plate is usually the first victim of this underwater collision. However, if you've damaged the drive plate, it's unlikely you've damaged the gear box. General wear and tear appears to be another cause - and because canal boats don't have a clutch arrangement, gear boxes tend to receive a fair bit of abuse, so go easy and regularly service them.
Fan belts - Always carry a spare, and before setting off develop a routine which includes checking the condition of these. Simply twist the belt and if there are cracks or the edges are starting to look ragged it's time for a new belt. If you hear 'squealing' from an old belt it's usually an indication a replacement is needed. If it's from a new belt, an adjustment is required. This is simple to do and worthwhile knowing how to.
Couplings - if the bolts connecting the propeller shaft to the engine are loose, any movement will either sheer them off, resulting in loss of propulsion, or make the coupling bolt holes oblong, resulting in delayed drive. Eventually the coupling will need to be replaced, and you may even have to change your prop shaft if the coupling has damaged it. A simple check before each journey will stop this happening.