Choosing the Best Fire Extinguishing Systems for Your Boat—Part I

Fortunately, fires on board boats are relatively rare compared to other potential disasters. The Coast Guard’s 2020 report indicates only 47of some 5,000 reportable accidents involved the ignition of fuel or vapor. Only one of those accidents resulted in a casualty. But forty-six lead to injuries. 

Fires may be rare, but they are very dangerous on board. They can create one of the few situations where abandoning ship is necessary in a boat still afloat.

And note there are likely hundreds of smaller boat fires where there are no injuries each year, so they are not reported to the Coast Guard.

Insurance adjusters say about 90 percent of onboard boat fires start in the engine room—no surprise there. More than half occur because of electrical wiring issues. Faulty wire insulation or loose connections, a few drips of fuel, a spark and there’s trouble.

Of course, the bad thing about engine room fires is that they very quickly get into the fuel system itself, and fed by explosive gasoline or flammable diesel, a fire becomes unstoppable without major extinguishing capabilities.

Another possible fire source is the galley, but since this is a much more visible area, a fire starting here is likely to be discovered quickly when easily controlled. And while cooking oil is flammable, there’s no immediate danger of the main fuel supply igniting.

Portable extinguishers are the first line of defense on the vast majority of boats. That’s why they’re required for most powerboats by state and USCG regulations as well as those in most European countries. 

They’re compact, inexpensive and can be placed at multiple locations aboard so that they’re always easily within reach.

Fire extinguishers are classified based on the type of fire they’re designed to put out. 

•      Class A extinguishers are designed to put out fires in wood, paper or fiberglass. 
• Class B extinguishers are designed to put out liquid fires including gasoline and diesel fuel as well as cooking oil, etc. 
• Class C extinguishers are designed for live electrical/wiring fires. 

Class B extinguishers are the type required by most marine regulations. There are some extinguishers rated “B-C” which cover the fires most likely to occur on boats. (You can put out a Class A fire with water, of course.)

Some states have no requirement as to the size of the extinguisher. A 2.5 lb. model is compact and easily stowed where you can reach it on almost any boat. But, it’s its really designed for small fires such as a galley fire. Don’t expect it to put out a blaze, particularly if fiberglass is burning. Florida and other states require at least two Class B’s, with no output requirement, on boats 26’ to 40’ LOA and at least three Class B’s on boats 40’ to 65’. 

This makes sense because quickly applying the contents of a small extinguisher easily within reach to a fire that has not had the chance to spread will save your boat. 

If your boat is longer than 65 feet, check the federal regulations.

The USCG has more stringent requirements, so if you operate outside state waters—3 nm to 9 nm from shore depending on state regulations--take heed.

Automatic Fire Extinguishing Systems

While a portable extinguisher applied to a flame early on will save your boat, you may not realize there’s a fire starting until it’s too big to stop with a portable. By the time you see flames shooting out of the engine hatch, the situation may already be out of hand. And getting within extinguisher range on a fully-developed gasoline fire is very dangerous since a fuel tank explosion is likely. 

While you MUST have an approved portable fire extinguisher—or several—aboard to be legal on most powerboats, if you have inboard or sterndrive engines, it’s wise to also have an integral fire suppression system in the engine room as well. 

In general, boats are required to have a fire extinguisher on board (not a fixed automatic system, but a functional, fully charged extinguisher) if the boat has an engine and meets any of the following conditions:

• Your boat has closed compartments where portable fuel tanks may be stored.
• Your boat has a double bottom that is not sealed to the hull and that is not completely filled with flotation materials.
• Your boat has closed living spaces.
• Your boat has permanently installed fuel tanks.
•  Or if your boat has any inboard engine.

It’s not required by law to carry a fire extinguisher on other types of boats but it’s still highly recommended. Fires can happen unexpectedly and it's always a smart idea to be prepared.

For larger yachts, extinguishers and fixed fire suppression systems are required, and must be inspected and re-certified annually to satisfy insurance requirements in many cases. 

Even if your boat does not have to have a fire suppression system, they are a really good investment.

You may save significantly on yacht insurance due to a well-maintained and certified system, and some companies may not even insure your boat without such a system.

Fire suppression systems are relatively inexpensive insurance for you, your family and crew and your boat. Basic models like the Elide Fireball suitable for stopping galley fires can be had for under $100, while a system capable of taking on an engine room fire in a twin-diesel yacht goes for around $3000—less than the cost of a tank of fuel, in many cases.

A fixed fire suppression system is always on watch and triggers automatically, day or night, whether you are aboard or not. It’s by far your best bet to fight a blaze when there’s still a good chance of keeping it contained.

Why You Might Want to Upgrade Your Existing System

Older boats might still have fixed CO2 systems, which are now considered dangerous should anyone be in the engine room or other space when the system discharges. These should be replaced as soon as possible.

Halon systems were discontinued in 1990 for ozone-­depletion concerns, but the gas is still legal in existing systems. The same is true of halon-replacing hydrofluorocarbon gases, such as Dupont’s FM-200 (HFC227ea), which are being phased out because of climate-change concerns from leaks and accidental discharge. 

The replacement is fluoroketone such as 3M’s Novec 1230 or HFC 227ea. These put out a fire almost instantly and leave no residues. And, the substance safely breaks down in the atmosphere.

(In fact, they can discharge without you even knowing about it, which is why they all include a monitor on the bridge to indicate whether the system is charged and ready or has been discharged.)

3M says their Novec 1230 fluid evaporates 50 times faster than water, and that you could soak a paperback book in a bath of the fluid and within a minute, pick it up and read where you left off.

Yachts over 70 feet long often have ­custom-engineered fire systems with pipes to spread ­firefighting agent throughout the engine room. These usually rely on heat-activating devices that sense rapid changes in air pressure during a fire to trigger everything at once. They are somewhat more expensive, but a minor item compared to the cost of most big-boat equipment.

Remember, just about the only reason for abandoning a boat at sea is fire—otherwise, you’re nearly always better off staying aboard a hull that is not in imminent danger of sinking. But a boat fully involved in fire due to intense heat, smoke and danger of explosion makes it more dangerous to stay aboard than to go into the water—hopefully you have a raft that can be launched before it’s too late to do so. 

A complete system includes the fire suppression systems in the engine room, the monitors at the helm and smoke detectors in all enclosed cabins. With larger boats, portable extinguishers located within easy reach forward are also a wise addition. 

For diesel-powered vessels, a relay system to automatically shut down engines, gensets, and ventilation, for ABYC A-4 compliance, is also needed.