Although it’s a fortuitously rare occurrence, fire is one of the biggest potential dangers on board any boat. When we encounter fire on land, we normally think in terms of evacuating a building, or the vehicle in which we’re travelling. However, at sea that would mean abandoning to the liferaft – not a decision to be taken easily. There’s therefore no substitute for ensuring fire cannot take place on board, here are a few ways to reduce the risk of fire on your boat.

Fire prevention at sea

US Coastguard fights a fire in winter at a marina – a fire at sea is even more dangerous.

Cooking appliances

Open flame cookers are often thought to be a key source of fires on board, but in general are fairly safe providing a few key rules are understood. Firstly, there should be a stout crash bar across the front of the cooker to prevent crew members falling against the appliance in a seaway. It’s also important to exercise extreme caution if accessing a locker behind the cooker, as almost every item of technical clothing is made of materials that burn easily. Although it’s not often stated, the importance of this should not be overlooked and there’s at least one well-known British boat builder that won’t put a locker behind the cooker for exactly this reason.

Gas systems

It’s the almost ubiquitous gas systems that have a much bigger potential to start a fire, or worse, an explosion that destroys the yacht. The problem is that both the common fuels used for bottled gas – butane and propane – are heavier than air. This means that any gas that leaks will stay in the boat, eventually collecting in the bilge, until the point at which it builds up to an explosive concentration. Despite this, it’s all too easy to be complacent about gas safety. Ensure the perishable components of the system, including regulator and flexible hoses, are replaced at appropriate intervals.

For more on this see: Gas safety onboard: guide for yachts and powerboats.

Electrical problems

The electrical system is arguably the most common root cause of onboard fires – 12V batteries can easily deliver enough energy to melt a cable that has short-circuited, setting fire to adjacent woodwork, soft furnishings or vinyl headlining. And that’s before we start thinking about 240V shore power systems, or mains voltages delivered via an inverter.

Marine electrical systems – fire prevention

The standards of marine electrical installations has tended to lag well behind those of domestic and automotive systems.

It’s therefore important to ensure that the boat’s electrical installation is of a good standard and regularly inspected. However, the standard of marine electrical installations has historically lagged well behind that of domestic wiring and the automotive industry.

Nevertheless, a good place to start is to check that insulation on cables is intact, that they are supported at regular intervals and, crucially, that each circuit us protected by a fuse or circuit breaker of an appropriate size. This latter point is frequently misunderstood – the function of the fuse is to protect the wiring, not any devices plugged into the circuit. Installing a fuse of too high a rating – or bypassing one altogether – therefore risks smouldering-hot wiring and its attendant fire risk. Even if the temperature doesn’t reach that stage, the heat generated in the wiring will still be drawing unnecessary power from the boat’s batteries.

On older boats it’s important to be aware that additional equipment may have progressively been added to circuits that are now underspecified in terms of wire size for the loads that are being drawn. Equally, corroded connections will increase the circuit’s resistance, which will create excess heat at that point.

For more on this, see: Marine electrics: how to use good terminals and tools


Battery maintenance – fire prevention essentials

A bad connection due to a cracked terminal caused the post on this battery to melt.

It’s also important to check the battery installation itself. They must be strapped down so that no movement is possible – even if the boat becomes inverted – and the terminals protected so that there is no chance of them becoming bridged and therefore short-circuited by anything else stored in the same compartment. Finally, wet cell batteries emit hydrogen gas during the charging process, so there needs to be a small vent at the top of battery compartment to allow this to escape and prevent the hydrogen building up into an explosive concentration.


Diesel engines are considered a low fire risk as the fuel is safe, so again any problems in this respect are most likely to be associated with the electrics. However, if your boat is powered by petrol engines it’s worth noting that any spilt fuel or vapour has the potential to form an explosive mix in the same way that gas for cooking appliances does.

For tips on keeping your engine room safe, see: How to secure cables and hoses in your engine room.


While heaters are unlikely to directly set fire to a boat, poor installation certainly has the potential to create a fire risk. This is most likely to arise from heat transferred by inadequately insulated ducting, diesel heater exhausts, or chimneys to the boat’s structure, soft furnishings or items stowed nearby.

It’s important to appreciate the very high temperatures associated with boat heaters – diesel units may produce exhaust at 400 degrees Celsius, while solid fuel stoves can also see very high temperatures in their chimneys. This again means that proper installation is essential, including heat shields on bulkheads and where the chimney or exhaust passes through the hull or deck.

More on boat heating here: How to choose and install boat heating.

Soft furnishings and headlinings

It’s also worth analysing the materials on board that may help to fuel a fire. There’s not much that can be done about the fibreglass structure and timber joinery, but soft furnishings are another matter. While most recent yachts should employ combustion modified foam, that was not the case a couple of decades ago.

Similarly, it’s worth checking the flammability of the vinyl headlinings that were used on almost every production yacht over a period of several decades – if these were to flare up in a fire then you would stand little chance of being able to remain below decks long enough to fight the blaze.

Preventing a fire onboard

On board fire prevention therefore encompasses a number of different domains. Once you’ve taken all sensible precautions to minimise the chances of fire, then all that’s left is to ensure you have a full armoury of fire fighting equipment and the knowledge to use it effectively.

Written by: Rupert Holmes
Rupert Holmes has more than 70,000 miles of offshore cruising and racing experience, in waters ranging from the North Sea to the Southern Ocean and Cape Horn. He writes about all aspects of boat ownership and marine travel, including destinations, seamanship and maintenance, as well as undertaking regular new boat and gear tests. He currently sails around 5,000 miles per year and in the past couple of seasons has cruised from the UK to the Azores, as well as winning his class in the 2014 two-handed Round Britain and Ireland Race. He also owns two yachts, one based in the Mediterranean and the other in the UK.