Fire Suppression Systems: Must-Have Equipment
Engine-room fires are mercifully rare, but every so often, one does occur. The engine room is the most likely place on an inboard-powered sail or powerboat or sterndrive boat for a fire to get started. If the fire breaks out while you are out on the water, the lives of everyone on board are at risk.
Highest Risk
Specifically, the United States Coast Guard estimates that 90% of all fires on a boat occur in the engine room. It is easy to see why. The compartment has the engines, the fuel and the electrical systems all in a confined space. This is also where most of the heat and vibration are generated. Screws, clamps and fittings are most likely to work loose in the engine room.
Then, a spill and a spark are all it takes.
If a fire breaks out when the boat is unattended or in storage, the danger to human life may be less, but the potential property damage could be dramatically greater. Consider the liability if it’s your boat that initiates a fire that takes down a storage building of other yachts.
Smaller boats are required to have one of two classes of fire extinguishers: A Class B extinguisher for combustible liquids (such as gas and oil) and a Class C extinguisher for electrical fires. In the United States, a boat shorter than 26’ (7.93 m) must have a 5-B extinguisher on board. A boat that measures 26’ to 40’ (7.92 m) needs two 5-B or one 20-B.
On a handheld fire extinguisher, the number before the letter on the extinguisher relates to its firefighting effectiveness. For example, a 3B device will put out a larger fire than a 2B device. Although regulations specify Class BC, get an extinguisher with an ABC rating. That covers more potential problems.
Built-In systems
For a boat with an engine contained in a compartment, a built-in system offers 24/7 unmanned protection. It’s the safest, fastest way to combat an engine-room fire.
A built-in system delivers the fastest response and will probably help to minimize property damage and human risk in the event of a fire. And new boats can catch fire, too. “New” is no guarantee of safety.
Without a built-in system, when a fire is discovered, the boat captain or crew must first locate a portable extinguisher, move to the point of the fire, in the case of an engine room, open the hatch or doorway (which incidentally allows in more oxygen creating a larger fire), then point the dry chemical extinguisher at the base of the fire, discharge and hope for positive results.
Diesel fuel is safer to handle than gasoline but in all cases, opening the hatch when a fire is burning will add enough new oxygen to create more danger of explosion and higher chance of human injury.
You may be surprised to learn that a built-in fire system is not required until the boat is longer than 65' (19.81 m) as well as being classed ‘inspected vessel’. Also, boats that carry passengers (such as charter fishing boats) are required to have a built-in system. But, common sense says that it is highly recommended that all boats with inboard or stern drives should have a fixed fire extinguisher system. We’ve regularly seen integrated systems on boats as short as a 21’ (6.4 m) bowrider. It just makes so much sense.
Manual and Automatic
The built-in fire suppression systems can be activated either manually or automatically. All have a tank that can be located somewhere in the engine room area (according to the manufacturers specifications) and these extinguisher tanks automatically discharge their fire suppressant at a pre-set point. For instance, a Fireboy system automatically discharges when the temperature reaches 175 degrees.
The suppressant ‘smothers’ the fire with chemical or gas that will not support combustion. When the system discharges, it smothers the running gasoline engine (as long as that is drawing its intake air from the engine room environment and not an outside intake). That is not true for diesel engines.
Diesels require an automatic engine shut down. A diesel will not automatically stall with the introduction of the fire extinguishants; a separate system is required to stop the diesel, otherwise it will simply consume the agent and continue running.
Environmentally Friendly
Some time ago, these built-in fire suppression systems used Halon gas but it was discovered that Halon was damaging to the environment. In 1994, Fireboy elected to cease the sale of Halon systems. Recycled Halon was allowed to be sold, but there was to be no new Halon manufacturing. Europe moved quickly to ban Halon, and in the USA, effective on January 1, 2007 new boats could not be equipped with recycled Halon systems either.
Other substances were developed and now chlorotetraflkouroethane and heptaflouropropane are used instead; both chemicals are manufactured by DuPont. Chlorotetrafluorethane FE241 has an ozone depletion potential (ODP) of .02. FE241 is not permitted in Europe and several other countries.
HFC-227ea Heptafluoropropane has an ozone depletion potential of zero. Additionally, HFC-227ea is approved for use in occupied/manned spaces. FE241 and HFC-227ea are non-corrosive and non-conductive. When the clean-agent system discharges there is no residue, or powder substance to clean up. It does not affect electrical or mechanical equipment.
New Approach
An alternative system uses ultra-fine, potassium-based aerosol. Space and weight requirements are minimal and, in many applications, the small size of systems like the Nautical Fire Suppression Stat-X aerosol generator makes them the only viable option. A low installation cost makes them an acceptable fire protection solution.
Another question is how to properly size a fixed fire extinguisher system. The answer is that the cubic volume of the protected space must be calculated (length x width x height). There can be no deductions for equipment or tanks, except as permitted in ABYC, section A-4. (Only boat builders may deduct fixed tanks in the protected space, proving they affix a label indicating they have calculated the space using this exception.)
Odds are that you’ll never experience an onboard fire. But, it doesn’t take much imagination to see the benefit of having a system on your boat.