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Fire on board: where it starts and what it destroys
Short answer
A boat is resin, foam, upholstery, fuel and plastic pipework within a few feet of each other.
Once a fire takes hold below deck the hull is usually beyond saving before help arrives,
so the question is rarely repair.
Fire is the casualty with the worst prognosis. Glass fibre, resin, foam cushions, diesel and plastic pipework all sit close together below deck, and a fire that takes hold there is rarely stopped by a hand extinguisher. Crews describe the same sequence again and again: smoke from a locker, a breaker that will not reset, and minutes later a boat nobody can board. That is why a fire claim is seldom a repair estimate. It is a total loss, and everything then turns on whether the sum insured still matches what the boat was worth.
A frequent cause of fire is the electrical system rather than the galley. Chafed or undersized cable, corroded terminals, retrofitted equipment without its own fuse, an overloaded shore power connection and ageing chargers head every list. Lithium batteries belong there too: they do not ignite more often, but they burn hotter and for longer, and water does little. Gas is the second recurring cause, because LPG is heavier than air and collects in the bilge, which is one reason the Boat Safety Scheme examination on the inland waterways of England and Wales looks so closely at gas and electrical work. Petrol engines add vapour in the engine bay, where ventilating before you turn the key is not advice but the fire precaution itself.
Two things are worth doing before the season and one after a loss. Before: a documented check of terminals and the main switch at fit out, a smoke alarm in the engine bay as well as the saloon, an extinguisher within reach of the berth rather than in a cockpit locker, and a residual current device on the shore power inlet. After: keep everything, including the burnt remains, because the investigation that follows a serious fire decides where the fire began, and that finding drives any recovery against a manufacturer or a yard. The other half of the work is the sum insured. A fire leaves no second chance to correct a figure that was set years ago, so review it after every significant refit and keep the invoices that prove the value.
Worth remembering
Minutes
is what a fire below deck gives you
Years
is how old the sum insured usually is
A fire claim is settled on the figure in the contract, because there is nothing left to repair.
Questions
What owners ask us about this
Where do boat fires often start?
Often in the electrical system rather than the galley: chafed or undersized cable, corroded terminals, retrofitted equipment without a fuse, overloaded shore power and ageing chargers. Fuel and gas vapour in the engine bay come next.
Does a lithium battery change the risk?
It changes the fire rather than the frequency. A lithium cell in thermal runaway burns hotter and for longer and does not respond to water, so proper battery management and ventilation matter more than with a lead acid bank.
What should I look for in the wording?
Whether fire, explosion and lightning are listed together as insured perils, whether the boat stays insured while ashore over the winter, and whether a seasonal contract leaves those months open. Read the clause on the sum insured at the same sitting.
Why does the sum insured matter so much here?
Because a fire claim is usually a total loss. With a repair there is room to argue about the estimate, with a total loss the figure written into the contract is the ceiling, and no survey after the event can raise it.
Related
Not sure whether you qualify?
Whether it is “Fire on board: where it starts and what it destroys” or another question: send us your residence and the flag your boat flies. You will get a straight answer in one email; including a no, if that is the answer.
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