Fires on Boats

Shipboard fires present special problems ranging from small fires in cabin cruisers to tanker fires involving thousands of metric tons of oil. Some of the special problems include complicated interior layouts, the danger of capsizing, and the difficulty of pinpointing and gaining access to the source of the fire.

The special equipment necessary for fighting marine fires range from the simple fire extinguishers and pumps on small, high-speed craft to foam-making apparatus, and special built in carbon dioxide fire extinguishing systems on large Motor Yachts. Familiarity of all the fire-fighting equipment found onboard and its use should be amongst the top priorities of the captain and crew before departing on any lengthy journeys.

At the Fire

The basic tactics of fighting a fire can be divided into the following categories: rescue operations, protection of further equipment exposed to the fire, confinement of the fire, extinguishing the fire, and salvage operations

Extinguishers for Class B Fires

Class B fires are put out by excluding air, by slowing down the release of flammable vapors, or by interrupting the chain reaction of the combustion cycle (See diagram). Three types of extinguishing agents - carbon dioxide gas, dry chemical, and foam are used for fires involving Flammable Liquids, Greases, and Oils.

Carbon dioxide is a compressed gas agent that prevents combustion by displacing the oxygen in the air surrounding the fire. The two types of dry chemical extinguishers include one that contains ordinary sodium or potassium bicarbonate, urea potassium bicarbonate, and potassium chloride base agents; the second, multipurpose, type contains an ammonium phosphate base. The multipurpose extinguisher can be used on class A, B, and C fires. Most dry chemical extinguishers use stored pressure to discharge the agent, and the fire is extinguished mainly by the interruption of the combustion chain reaction.

Foam extinguishers use an aqueous film forming foam (AFFF) agent that expels a layer of foam when it is discharged through a nozzle. It acts as a barrier to exclude oxygen from the fire.

Extinguishers for Class C Fires

The extinguishing agent in a Class C fire extinguisher must be electrically non-conductive. Both carbon dioxide and dry chemicals can be used in Electrical Fires. An advantage of carbon dioxide is that it leaves no residue after the fire is extinguished. When electrical equipment is not energized, extinguishers for class A or B fires may be used.