Fires on boats can become serious very quickly. Luckily, it’s easy to equip yourself with the knowledge and kit to prevent – or tackle – a blaze…

Understanding Fire

A fire requires a combination of oxygen, fuel and heat. This is commonly called the fire or combustion triangle and is a simple model for understanding the three elements required to start a fire To put a fire out, it must be deprived of one or more of these three elements, but using the wrong extinguisher can make the situation worse.

  • Fires are classified into five groups:

A fires involving solids such as paper, wood, or textiles

B fires involving liquids such as oil, diesel and petrol

C fires involving gases

D fires involving metals

F fires involving cooking oil and fat

Fires involving live electrical equipment are not included in this list because once the electrical source has been isolated the combustible material fuelling the fire falls into one of the categories above. However, you may see these referred to as Class E fires elsewhere.

Fire Extinguishers

Different media are used to fight different types of fire. The most common are water, dry powder, foam and Carbon Dioxide (CO2). Table 1 (below) provided information on which type of extinguisher should be used on each class of fire.

  • Fire extinguishers are categorised to indicate the size of fire for which they are suitable.
  • When buying an extinguisher, look for a number/letter code on the canister, like 5A or 113B. The letter shows the fire group, the number is the size of fire it can tackle. The higher the number the more effective the extinguisher.
  • Extinguishers capable of dealing with more than one group will have two codes – 5A/34B, for instance.
  • 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.
  • It is essential that everyone on board knows where they are stowed and how to use them.
  • Extinguishers should be serviced at the appropriate intervals by an approved service agent


When first sold or put into use, vessels built for the UK market in compliance with the UK Recreational Craft Regulations 2017 (RCR2017) and for the EU market in compliance with Directive 2013/53/EU (the Recreational Craft Directive - RCD), must ensure they do not endanger the health and safety of persons, property or the environment. That includes protection from risk and spread of fire and the provision of fire-fighting equipment appropriate to the fire hazard.

Both the UK and the EU recognise that conformity with the fire protection requirements can be achieved by applying ISO 9094, Small craft - Fire Protection which specifies, among other things, the minimum requirements for firefighting equipment. However, further means of firefighting may be necessary (or required by law). This applies particularly to UK registered private pleasure vessels over 13.7m, which fall under UK Merchant Shipping Regulations, those that are required to comply with the UK Boat Safety Scheme certificate and those that are used for commercial purposes such as training and charter.

  • Even if firefighting kit is not mandatory, any vessel that is constructed of, or carries, any flammable materials should carry firefighting equipment.
  • When planning fire safety, consider the amount and type of combustible material on board, where extinguishers might be needed and how to stow them.
  • Fit a fire alarm and test it regularly.

The right place

On board, it’s good practice to stow fire extinguishers at the exits from each area of the accommodation spaces – by the door of each cabin and by the companionway – so you can fight the fire and keep escape routes clear.

  • 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.
  • On a small, open boat with no cooker or internal combustion engine, a single 5A/34B rated extinguisher may be sufficient. Store it away from the engine and fuel tank (if they’re fitted) and protect it from salt water.
  • If your boat has cooking facilities avoid cooking with oil or fat and keep a fire blanket close to hand; it is often the most effective extinguisher particularly for a small type F fire.
  • Table 2 (below) provides a guide to the number and type of extinguishers recommended for various sizes of boat.

Flammable liquids and gas

In an ideal world there would not be any flammable liquids on a vessel. But the reality is that most boats will carry spare diesel for the main engine, petrol for an outboard motor and perhaps chemicals for general maintenance. It’s important that these are stowed in areas that are well ventilated. Petrol and other fuels should be kept in a dedicated locker that vents and drains outboard.

  • All flammable liquids should be stowed upright and should be lashed or secured to prevent them moving about and rupturing the containers. Keep lids tight
  • Another important consideration is gas equipment installation. If you suspect a gas leak, shut off gas at all shut-off points, extinguish any flames and ventilate the vessel (including bilges) until all trace of gas has gone.
  • Fitting a gas alarm and test it regularly.

Engine rooms

It should be possible to tackle an engine room blaze without allowing air to enter the 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 gases as the fire-extinguishing media.

Table 1 – The Different types of fire extinguisher:


Media Advantages Disadvantages Suitable for fire groups


Good cooling properties


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



Leaves a residue

Effectiveness can be reduced by wind

Can cause breathing difficulties

This is dependent on the type of 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

Not 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

Can cause an asphyxiant atmosphere if used in a confined space

Disperses rapidly in open spaces 

Most effective for small class B fires


Table 2 - Extinguisher recommendations by boat size:

Approximate length of vessel  Number of fire extinguishers (consider one for each sleeping cabin)  Combined fire rating

under 7m


                     2           10A/68B

7 - 11m


                     2            13A/89B 

11 - 13.7m


                     3            21A/144B 


First published in the RYA Magazine, Summer 2020. Revised 05/2021