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How to use a Fire Extinguisher

How to use a Fire Extinguisher

Fire Extinguishers

We know we need them on board, but how many do we need and how do they work? A man demonstrating the PASS technique for fighting a fire.The Coast Guard requires boats to have at least one B-1 marine fire extinguisher on board. Depending on the size of your boat you may need more than one. Boats under 26' have to have at least one B-1 fire extinguisher on board. Boats 26'-40' need to have at least two B-1 fire extinguishers on board. If the boat has a USCG approved fire extinguisher system installed for protection of the engine compartment, then the units may be reduced. Please refer to the chart for the number of extinguishers required for your boat. Our recommendation is to have a tri-class (1A:10BC) fire extinguisher on board your boat. We also suggest you have more than the Coast Guard requires. Now we know how many we need on board, but how do they work?

Kidde Extinguisher Recall

There is a recall on certain Kidde fire extinguishers.



How to use a Fire Extinguisher

A person fighting a controled fire on land in an empty parking lot.

Know how to use a fire extinguisher before you are in a situation where you have to use it. Fire extinguishers are labeled according to the type of fire on which they may be used. Fires involving wood or cloth, flammable liquids, electrical current or a combination of those will each react differently to extinguishers. Using the wrong type of extinguisher on a particular type of fire could be dangerous and make matters even worse.Simply Remember the P-A-S-S Word!In the heat of the moment reading the directions on the extinguisher is an after-thought.

  1. Pull the pin at the top of the cylinder
  2. Aim the nozzle at the base of the fire
  3. Squeeze or press the handle
  4. Sweep the contents from side to side at the base of the fire until it goes out

Fire extinguishers are labeled with the type of fire they can suppress. Most common marine fire extinguisher will be labeled as B:C or A:B:C.

Fire Extinguishers Close Up

Firing Mechanism

All extinguishers have pins or pull tabs that have to be removed to activate the unit. plastic tie This feature prevents false activations. Some of our testers had difficulty removing the pin because it was held in by a thin sacrificial plastic tie.

We found most extinguishers had two levers that are squeezed together to activate. This is in contrast to the smaller 5-BC units designed for personal watercraft, which use a more simplified firing mechanism. Kidde uses a plunger mechanism and First Alert uses a trigger to activate their unit. Both are designed so that the firing mechanism does not extend past the width of the cylinder.


There is a gauge on most extinguishers to measure the pressure of its contents. A fire gauges extinguisher can be "overcharged" meaning the contents are under too much pressure, "discharged" meaning that there is not enough pressure to work correctly or "in the green" which means that the unit is properly charged.

The standard round gauge was found on all but the personal watercraft units. Over time, or after it has been used, a fire extinguisher will loose pressure and will cease to work properly.

Most of our test extinguishers were not rechargeable. A rechargeable extinguisher can be taken to a service station for maintenance. If it is not rechargeable then it should be discarded when the gauge reads ‘discharged’ or it has been in service for 12 years from manufacture.


The time it takes to find a fire extinguisher in a cluttered locker could mean the mounting difference between saving your boat or having to jump overboard. A properly mounted fire extinguisher should be at every exit and near the engine compartment. This keeps your back to your escape route and an extinguisher ready near the likely sources of fire aboard. In the galley, an extinguisher should be mounted so you do not have to reach over the stove.

On open motorboats, fire extinguishers should be mounted in an easily accessible location. A non-marine-rated fire extinguisher could have parts that corrode or do not secure it firmly to a moving boat. Be sure to purchase a marine-rated fire extinguisher that has a noncorrosive metal or plastic bracket that can secure it firmly to a vertical surface.

Partial Discharge

Fire extinguishers are designed to rapidly release fire retardant onto their target. partial dischargeWhen activated, the firing mechanism pierces a gas cylinder exerting additional pressure in the cylinder propelling the retardant out of the open nozzle. During our test we found that a partially discharged dry chemical extinguisher was inoperable after a few minutes. If you have a flare up after several minutes, a partially discharged unit might not work. It is important to replace or service the extinguisher as soon as possible.

Extinguisher Contents

Dry Chemical Extinguisher

The economically priced, handheld dry chemical fire extinguishers are the most common type found aboard recreational boats. The retardant functions by coating the material on fire and removing the oxygen from the flame similar to throwing a fire blanket on a fire. An accurate aim at the base of the fire directs the retardant at the source. Sometimes our testers found that by aiming at the top or middle of the fire, they could not put out the fire completely, and frequently required an additional extinguisher to finish the job. Clean up of dry chemical extinguishers can be messy and it is corrosive to electronic components and wiring.

Halon Replacement Extinguishers

Unlike dry chemical extinguishers, the Halotron extinguisher displaces oxygen from the fire. This gaseous fire suppressant allows for easy sight of the fire and does not harm engine or electronic components. Halon replacement extinguishers are ideal for separated, enclosed spaces such as an engine compartments for use through a Fire-Port. All portable halon replacement units are safe to breath but fixed systems using FE-241 are not. Drawbacks for these fire extinguishers are the higher price and bulkier size.

A white fire port.

What is Right for Me?

A tri-class dry chemical extinguisher will meet most boaters’ needs. If you have concerns about damage to your electronics or your engine compartment lacks a fixed system, a strategically placed Halotron product could serve you well.

As fire extinguishers are required on most boats, you most likely have one aboard. But chances are, you’ve never needed to use one, and might not know the proper technique for using one.

Take the time to read the directions on your fire extinguisher – you might be surprised about what it can and can’t do. For more information on fire extinguishers, check out the Foundation Findings that we did in 2009 testing different extinguishers on different fires as well as testing volunteers on how quickly they could figure out how to use one.


Vessel LengthNo Fixed SystemWith approved Fixed Systems
Less than 26'1 B-10
26' to less than 40'2 B-1 or 1 B-II1 B-1
40' to 65'3 B-1 or 1 B-II and 1 B-12 B-1 or 1 B-II

Testers' Choice

Staff Choice: First Alert Extinguisher by Kitty.

The Kidde and First Alert 1-A:10-B:C are the Foundation picks for best all around for the price. About $5 more per extinguisher will give you the added security when trying to put out a small fire aboard your boat.

How to use a Fire Extinguisher