The disappearance of the artfully cursed gasoline auxiliary engine and the end of the era of the pressurized alcohol galley stove have improved the chances for avoiding a fire on board a sailboat. But at the same time, the addition of massive DC-power systems, propane stoves, and fuel tankage equivalent to that of a motorboat has upped the ante when it comes to a galley flare-up or an electrical short-instigated fire getting out of control. Small fires can become all-consuming conflagrations in an alarmingly short period of time. The science says it all: A fast-growing fire doubles in size every 30 seconds.
The best risk management is based upon reason, and it's why every skipper needs to consider the prospect of fire breaking out on his vessel and how those on board should respond. These what-ifs that arise from such introspection will lead to more data gathering and a plan of action that needs to be shared with the crew. Statistics show that though fires infrequently occur on cruising sailboats, their effect can be devastating. The U.S. Coast Guard and the American Boat & Yacht Council wisely see the threat as very real, and they've put out regulations and recommendations that spell out both how certain systems should be installed and what firefighting equipment is mandatory.
Heat, fuel, and oxygen are the rudiments of combustion; if any one of these is removed, the blaze is extinguished. As with all elegantly simple explanations, this information is often ignored until it's too late. For example, a small two-pound dry chemical fire extinguisher in either the hands of an expert or an amateur about to succumb to the fight-or-flight reflex has only about eight to 12 seconds of firefighting potential once the trigger lever is depressed. In the heat of the moment, many an untrained amateur has expended the vaporized dust on the flames leaping high from the burning surface rather than spreading the extinguisher's limited contents on the base of the flames, where it will have the best results. The latter approach smothers the fire by creating a barrier between the fuel and the oxygen.
Understanding the Equipment
Fires are broken up into three classes based upon their combustion profile. Wood, paper, and other natural and synthetic fiber fires that leave an ash residue are typed as a Class A, and are best extinguished by lowering their temperature via flooding with water or aqueous foam. That's also good reason to consider a high-pressure, high-volume water system with a sink hose and spray head or a second in-cabin tap and hose linked to a powerful deck wash-down pump to be firefighting allies.
Meanwhile, fire extinguishers may be your first line of defense for Class B and Class C fires, but an extinguisher's operational time is short, and even a few well-placed buckets of water may save the day once the eight- to 12-second operational lifespan of a dry-chemical extinguisher is over.
Flammable liquid fires (Class B), typified by gasoline, diesel, or alcohol, are best tackled by smothering the flames with a fire blanket or oxygen-blocking extinguisher agent. Dry chemical, foam, CO2, Halotron, and other non-toxic Halon replacements all do the job. All dry chemical extinguishers should be removed from their bracket and inverted every month or so in order to keep the contents from solidifying. Also worth a mention is the inferior nature of most flimsy, mild-steel brackets that come with extinguishers. Spending some time or money on improving how these vital safety tools are housed is worth the expenditure. In addition to the extinguisher near the galley stove, reachable even if the appliance is ablaze, there should be an extinguisher in a cockpit locker and one near the skipper's berth.
The table "Extinguishers and Their Uses" (see below) describes the types of extinguishers available. Built-in systems, such as those offered by Fireboy, can flood the engine room with an oxygen-blocking gas that can stop a blazing fuel fire in its tracks. But those who install such systems need to keep in mind that what kills a fire can also impact human respiration. Some years ago a friend of mine accidentally engaged a fixed, CO2 fire-suppression system while he was in the engine room of his boat; the gas quickly rendered him unconscious, and his wife, responding to his plight, succumbed to the same asphyxiation. Both died in the mishap.
This tragedy underscores the need to realize that limiting oxygen to quell a fire is tricky business. On one hand the rule of fire fighting is to close hatches and ports in order to lessen the air inflow. But the crew also must recognize how dangerous oxygen depletion, acrid smoke, and toxic fumes in a closed up boat can quickly become a lethal atmosphere. Compressed liquid extinguishers that emit a gaseous cloud in a confined space such as an engine compartment vary in toxicity according to their suppression agent. Some systems use FE-241 that's meant for dispersal in an unoccupied space, while others use HFC-227ea, a gas that's safe if occupants are still in the cabin fighting a spreading fire.