Why do canal boats breakdown and sink?

River Canal Rescue in 2019 attended an average of 105 call-outs a week. 18 of these were for major rescues and repairs, chargeable outside membership, the remainder were classed as minor repairs.

weedhatch leaking

RCR attending to a boat sinking caused by leaking weed hatch

Minor repairs, typically taking two or three hours, were due to a range of technical and maintenance issues.

Fuel problems, frequently caused by diesel bug and contaminated water. ‘Diesel bug’ is an enzyme that lives off water in the diesel, either appearing as black dust/ soot or a black slime/jelly. Once in the system it clogs the engine’s fuel arteries and stops the engine working. Mild cases will respond to a biocide treatment such as ‘Marine 16’ which prevents bacterial growth and kills anything that may be forming in the tank. More severe cases require a diesel bug shock treatment. Dirt and debris can also block filters and contaminate fuel so check filters and tanks and service regularly.

Electrical issues were often due to overlooked connections. Boaters should check before starting a journey for corrosion, wires coming away, loose connections or disconnected wires and use a water resistant spray or petroleum jelly to stop damp getting into isolators and block connectors. Cable failures are often due to cable ends and terminals rusting. To prevent this, grease the end of the cable, particularly if leaving the boat for a long period of time, and when setting off, check for any roughness or stiffness. If fitting new cables, keep bends to a minimum (they’ll suffer higher stress and so may fail in the future). Poor connections may also result in electrical fires.

Alternator failures were mainly the result of the damp, hot environment which is not good for any electrics. If bilges are full of oil and water it can be splashed over the engine, hitting the electrical components. If left for a long period of time rust can also develop and affect their operation, so it’s important to check the bilges and run the engine frequently.

Starter systems often failed because of unsuitable or faulty batteries. A cranking battery delivers a high output quickly while a leisure battery delivers a lower continuous output, so needs regular charging to maintain capacity. If in a good condition, each battery in a bank generally requires two to three hours charging as a minimum to keep them topped up and will require more if discharged.

Battery failures could often be avoided by routinely checking and topping up cell water levels with de-ionised water. If one cell’s water level drops to below 50% it will bring the battery bank capacity down to the same level, irrespective of how good the other batteries are. Never mix batteries and always replace a whole bank of old with new.

Engine overheating could be due to an air lock or blockage in the cooling system. It can also be caused by a coolant hose rupturing, a water pump failing or a fan belt shredding. Or it could be the result of the engine being overloaded through overuse or debris on the propellor, or by a head gasket failure.

Striking underwater objects may damage the gearbox, propeller, drive plate, coupling, prop shaft, engine mount, hull or rudder. Gear box and drive problems can also be caused by general wear and tear if not regularly maintained. The loss of, or reduction in, propulsion is commonly due to the prop being fouled by debris such as weed or leaves, or tangled by rope or materials such as fabrics or plastics.

Most serious call-outs, typically taking engineers a day or more, are to salvage partly or wholly submerged or grounded craft.

sunk by lock cill

Boat caught on cill in wide lock and sunk.

Many sinkings could have been prevented if boat owners had monitored bilge water levels or installed an automatic bilge pump with float switch. Rainwater seeping into bilges can build-up and cause the boat to sit lower in the water, allowing canal water to flood in through outlets close to the water line. Water can also leak from internal tanks or pipes, bow thrusters, water pumps, stern tube seals and stern glands and from unsecured weed hatches.

And of course sinkings also occur after boats are held down by ropes when water levels rise, or when craft become inundated after getting caught on lock cills (as above) or gates or weirs. See our advice about Safe Locking and Avoiding Grounding.

Thanks to RCR for this information and images. To find out more about River Canal Rescue go to www.rivercanalrescue.co.uk check out their Facebook page, call 01785 785680 or email enquiries@rivercanalrescue.co.uk

All materials and images © Canal Junction Ltd. Dalton House, 35 Chester St, Wrexham LL13 8AH. No unauthorised reproduction.

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