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Once a fire on board a boat really takes hold, it is unlikely that it will be successfully tackled. It is therefore essential to observe good fire safety practice to minimise the risk of a fire occurring. Prevention is far better than cure.

If a fire does occur, it is imperative that you have sufficient fire fighting equipment to hand and that you know how to use it, if the fire is to be extinguished quickly and effectively.

A fire requires three elements: a combustible material (fuel), oxygen and a source of ignition (heat). To extinguish a fire it must be permanently deprived of one or more of these three elements (heat, fuel or oxygen). How this is achieved will depend on the type of fire.  Using the wrong extinguishing method can make the situation worse; the classic examples are the inferno caused by adding water to a chip pan fire and the dangers when attempting to extinguish an electrical fire with water.

Types of fire

The different types of fire have been classified into groups which are distinguished by a letter:

  • A are fires involving solids such as paper, wood, bedding etc
  • B are fires involving liquids such as oil and petrol
  • C are fires involving gases
  • D are fires involving metals
  • F are cooking oil and fat fires

Electrical fires are not included within this list as once the electrical source has been isolated the combustible material fuelling the fire will fall into the categories above.

Fire extinguishing media

Different media are used to fight different types of fire. The most common media are water, dry powder, foam and CO².

Advantages Disadvantages Suitable for fire groups


Good cooling properties


Should never be used on liquid, gas or electrical fires A only
Dry powder Versatile



Leaves a residue

Effectiveness can be reduced by wind

Can cause breathing difficulties

This is dependent on the ingredients of the powder with options of D only, B&C or A B C which is commonly found onboard boats

Good cooling properties

Can create a heat barrier

Larger extinguishers are more effective

Not usually suitable for electrical fires

A and sometimes B - suitability varies between different manufacturers

Does not cause damage or leave a residue

Can be used on live electrical fires

Can cause cold injuries if used incorrectly

Disperses rapidly in open spaces 

Most effective for small class B fires

Fire fighting power

As well as being classified for the types of fire they can tackle, fire extinguishers are categorised to indicate the size of fire they are suitable to tackle. For each type of fire there are specified test conditions for each level of extinguishing power.

The following is a greatly simplified explanation of the testing process, given to aid understanding of the fire ratings:

Type A fires: 5A, 8A, 13A, 21A, 27A
To test the fire fighting power for class A fires, a structure is built which is always 560mm high and 500mm wide. The length of the wooden sticks used to build the structure is the dimension that varies and this corresponds with the power indicated i.e. a length of 0.5m is used for a 5A extinguisher or 2.7m for a 27A extinguisher.

Type B fires: 21B, 34B, 55B, 70B, 89B, 113B, 144B, 183B, 233B
For type B fires, there are more variables. Of these variables it is the required volume of liquid for the test which is used to indicate the extinguisher's power i.e. 21B indicates that 21 litres of liquid are required.

Fire extinguisher ratings

The letter indicating the type of fire and number indicating the fire fighting capability are combined to create the fire extinguisher rating. Where a fire extinguisher is only capable of tacking 1 type of fire, it will only be marked with 1 rating e.g. 21A. If an extinguisher is capable of tackling more than one type of fire then it will be marked with the ratings for each type of fire e.g. 5A/34B or 13A/113B. They may also be marked with the weight or volume of product they contain. By combining the ratings of two or more extinguishers, a "combined fire rating" is created e.g. 2 x 5A/34B extinguishers would have a combined fire rating of 10A/68B.

Equipping private pleasure craft

The Recreational Craft Directive (RCD) stipulates that vessels built for the EU market when first sold must conform to ISO standard 9094 Fire Protection. The standard specifies minimum requirements for escape routes and the installation of fire fighting equipment and also provides guidance on fire detection.

The standard covers a practical degree of fire prevention and detection intended to give occupants of the craft sufficient time to escape from a fire on board. It should not be assumed that the application of the standard alone is sufficient, especially for older boats and those that pre-date the RCD.

Further means of fire fighting may still be necessary or may be required by law such as the UK Merchant Shipping Regulations specify the fire fighting equipment requirements for Class XII vessels (private pleasure vessels of 13.7m or more in length). Although the UK Merchant Shipping Regulations do not mandate fire extinguishers on  private pleasure craft of less than 13.7m in the UK, fire fighting equipment is specified for boats which are required to have a valid Boat Safety Scheme certificate.

Vessels operating under different flag states should check with the relevant national authority for that country as to what their requirements are.

Where fire fighting equipment is not mandatory it does not mean it is not required. Any vessel that is constructed of, or carries any, flammable materials should carry appropriate equipment for extinguishing fires and it is up to the owner to decide what fire extinguishers are needed and where to locate them.

When making this decision consideration should be given to the amount of combustible material on board, where fire extinguishers might be needed and how they could be stowed. It must also be remembered that the typical operating time for a fire extinguisher is about 30 seconds, so to gain maximum benefit it is essential for everyone on board to know how to operate the extinguishers and how to use them effectively.

Although one large extinguisher will be more effective at tackling a fire than using several smaller ones in turn, on a 12m yacht, one big fire extinguisher stowed in the cockpit locker would not be ideal if a fire were to break out in the forepeak, especially in a rough sea.

Being trapped in the accommodation is the most immediate danger from fire on a boat, it is therefore good practice to stow fire extinguishers at the exits to each area of the accommodation i.e. by the door of each cabin and by the companionway/door to the deck, so you can fight the fire whilst keeping the escape routes clear. The key is finding the balance between an extinguisher that is small enough to use at sea, but large enough to knock down the fire whilst water or a larger extinguisher (as appropriate) is fetched. Extinguishers should be mounted securely in a location that is easily visible and accessible but where they will not be in the way of the day to day operation of the vessel.

The following is provided as a guide: 

Approximate length of vessel  Guide to minimum number of fire extinguishers  Guide to minimum combined fire rating

under 7m


                     2           10A/68B

7 - 11m


                     2            13A/89B 

11 - 13.7m


                     3            21A/144B 
On a small open boat with no cooker or internal combustion engine a single 5A/34B rated extinguisher may be sufficient. It should be protected from salt water e.g. sealed in a clear plastic bag (heat sealable bags are ideal for this and can be easily torn open if needed) or carried in a dry bag with your basic safety equipment. Remember to store the extinguisher away from the engine and fuel tank.

All fire extinguishers should be serviced, as directed by the manufacturer in the instructions, by a competent engineer to ensure that they operate effectively in an emergency.

Galley fires

If your boat has cooking facilities then a fire blanket close to hand will frequently be the most effective extinguisher. A fire blanket when used correctly will quickly suffocate the fire, as it starves the fire of oxygen. A fire blanket should be positioned so it can be easily reached, without needing to lean over the fire, and should be a manageable size.

Another important consideration is gas equipment installation. Advice on this subject is given on the gas page.

If you suspect a gas leak shut off gas at all shut off points, extinguish any flames and ventilate the vessel (including the bilges) until all trace of gas is gone.

Dedicated extinguisher for the engine bay

For boats with an inboard engine, consideration should be given to how a fire in the engine compartment would be tackled. It is preferable to be able to do this without allowing air to enter the engine space, as this could make the fire worse. A small hole through which a fire extinguisher can be aimed is one solution, but many owners choose to fit a dedicated automatic extinguisher in the engine bay. The fire rating required will depend on the space in question and advice should be sought from the manufacturer. For larger spaces there are specialist fire systems available, often using inert gasses as the fire extinguishing media.


Halon extinguishers were previously widely used on boats as they were effective on a wide variety of fires as well as being a very efficient extinguisher. Halon however has ozone depleting properties and has been banned since the end of 2003.  Despite this, there are still some Halon extinguishers in existence. Should you have one it should be replaced and the Halon extinguisher should be disposed of through an approved channel. 

Stowage of flammable liquids

In an ideal world there would be no flammable liquids on a vessel. The reality is that most boats will carry things such as spare diesel for the main engine, petrol for an outboard motor and perhaps chemicals for general maintenance. It is important that these are stowed in area that is well ventilated. Ideally petrol and other fuels will be kept in a dedicated locker that is vented outboard. All flammable liquids should be stowed upright and should be lashed or secured to prevent them moving about and rupturing the containers.

The RYA would like to thank the Fire Protection Association for their assistance in producing this web page.

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