Fires at Sea
how to fight fire on a boat and ship
Fire has been used by humans for cooking, generating heat, light, signalling, and propulsion purposes, sometimes we need to know how to fight fire on a boat and ship. The negative effects of fire include hazard to life and property, atmospheric pollution
Fires start when a flammable and/or a combustible material, in combination with a sufficient quantity of an oxidiser such as oxygen gas or another oxygen-rich compound (though non-oxygen oxidisers exist), is exposed to a source of heat or ambient temperature above the flash point for the fuel/oxidiser mix, and is able to sustain a rate of rapid oxidation that produces a chain reaction.
This is commonly called the fire tetrahedron. Fire cannot exist without all of these elements in place and in the right proportions. For example, a flammable liquid will start burning only if the fuel and oxygen are in the right proportions.
We can think of this in simple terms as a “Fire Triangle” by just considering
It is important to identify potential fire hazards and do something about them to minimise the likelihood and minimise their effect should the worst happen. We have devised a short online course to raise awareness about fires on boats and ships in port and at sea.
Fire occurs infrequently in general areas of a vessel and if it does it’s a smokey electrical fire which is easily found and extinguished by one or two people. We also have to consider other fire hazards.
Engine Rooms – Fire occurs frequently in engine areas where fuel is present. Most fires are small but are hard to put out because heavy fuel oil will float on water and only spread the fire. Engine rooms have Carbon Dioxide, dry chemical or foam suppressant systems
Fuel – Gasoline fuelled engines use a fuel that can easily vaporise at atmospheric temperatures. The vapour can settle in the vessel and cause an explosion. If at all possible take the option for diesel fuel next time if you now work in a gasoline fuelled boat. Diesel is a much safer fuel because of a high vaporisation temperature.
Machinery – Machinery gets hot when it’s operating. An overheating bearing could cause a fire. Ships have combustion systems for generating steam, or internal combustion engines to generate electricity, or even turbine engines like jet aircraft, all of which get very hot and can cause a fire. The closed machinery spaces and the volatility of fuel, of lubricants or of hydraulic fluids around the hot machinery can lead to a fire, or even an explosion.
Electrical – An electrical fire is possible from many causes including short circuits, sparking from bad connections and light switches. You must also consider over loading leading to overheating.
Collision – colliding with another vessel or structure at sea could initiate a fire.
Galley – The ship’s company has to eat, so there’s a galley where food is prepared and cooking is done. There’d be the same fire hazards as in a restaurant kitchen, wouldn’t there?
Repairs – Repairs are undertaken on yachts and ships, and metal cutting and welding equipment used to fix stuff. Always consider what is on the other side of the area being welded – storage of fuel, clothing, foods, drinks etc.
Explosives and ammunition – Military and some “civilian” vessels face fire or explosion hazards associated with carrying munitions.
Types of Fires
Fire extinguishers are divided into four categories, based on different types of fires that they are used for.
Each fire extinguisher also has a numerical rating that serves as a guide for the amount of fire the extinguisher can handle. The higher the number, the more fire-fighting power.
Class A extinguishers are for ordinary combustible materials such as paper, wood, cardboard, and most plastics. The numerical rating on these types of extinguishers indicates the amount of water it holds and the amount of fire it can extinguish. Geometric symbol (green triangle)
Class B fires involve flammable or combustible liquids such as gasoline, kerosene, grease and oil. The numerical rating for class B extinguishers indicates the approximate number of square feet of fire it can extinguish. Geometric symbol (red square)
Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires – the risk of electrical shock is far too great! Class C extinguishers do not have a numerical rating. The C classification means the extinguishing agent is non-conductive. Geometric symbol (blue circle)
Class D fire extinguishers are commonly found in a chemical laboratory. They are for fires that involve combustible metals, such as magnesium, titanium, potassium and sodium. These types of extinguishers also have no numerical rating, nor are they given a multi-purpose rating – they are designed for class D fires only. Geometric symbol (Yellow Decagon)
Fire Extinguishers used on boats
Water extinguishers are filled with regular tap water and typically pressurised with air. The most common way to remove heat is to spray water on the fire; however, depending on the type of fire, this approach is not always the best option.
Dry Chemical Extinguishers
Dry chemical extinguishers are filled with powder, usually potassium bicarbonate or sodium bicarbonate (baking soda), and pressurised with nitrogen. Baking soda is effective because it decomposes at 158 degrees Fahrenheit and releases carbon dioxide, which smothers oxygen once it decomposes. Dry chemical extinguishers interrupt the chemical reaction of the fire by coating the fuel with a thin layer of powder, thereby separating the fuel from the surrounding oxygen.
Applied to fuel fires as either an aspirated (mixed & expanded with air in a branch pipe) or non aspirated form to form a frothy blanket or seal over the fuel, preventing oxygen reaching it. Unlike powder, foam can be used to progressively extinguish fires without flashback.
Carbon Dioxide (CO2) Extinguishers
CO2 extinguishers contain carbon dioxide, a non-flammable gas. They are so highly pressurised that it is not uncommon for bits of dry ice to shoot out. Since CO2 is heavier than oxygen and very cold, it displaces or removes oxygen from the surrounding area and cools the fuel.
Maintenance and servicing
Do not forget that fire extinguishers require care and maintenance in order to remain functional!
Common sense is your best safety tool. Thinking through the consequences before acting can have a dramatic impact towards a positive outcome. Make sur ethat you know how to fight fire on a boat and ship!