Saturday, September 24, 2022

Guest Post: Fire Preparedness Aboard Ship

 by Sean Smock

Sean is a member of our Facebook Group. This is his first post for us.

Let us consider the concern of fire while aboard a ship. We’re going to ignore anything with a professional crew, who have people trained in damage control and fire fighting, as well as boats which are too small to go very far from shore like rowboats, canoes, and daysailers. Instead, we will focus on ships that will be where you will be spending the night, far from shore, with many exciting ways in which they can catch fire. 

Much of what I’m discussing will be familiar to people who are experts at land based firefighting, or at least have some level of familiarity with land firefighting, as smoke detectors, the fire triangle/tetrahedron, extinguishing agents, and fire types are all factors on land as well as on the water. 

Detection is first because it is the most important. If you’re not planning on sleeping aboard the craft, and it’s a small enough craft for you to have line of sight on everything that’s liable to catch on fire, you can forgo a maritime smoke/fire detector. However, if you’re going to be sleeping or the vessel is larger, your options are “Set a fire watch” and “get smoke/fire detectors”. This is quite frankly the most important part of fire preparedness: an undetected small fire will become a big fire, and an undetected big fire will pose a major threat to life and limb for everyone on board. All effective action regarding fire requires that the fire be detected, and the earlier the better, because you can't put extinguishing agent on a small fire that you don’t know about. You can easily be trapped by, or overcome by the smoke and gaseous byproducts of, a larger fire that you are unaware of. If you do nothing else, buy a smoke detector. 

The Fire Triangle/Tetrahedron
In order to sustain flame, each fire needs three things:
  1. Heat
  2. Fuel
  3. Oxidizer
This gives you the fire triangle. Add the chemical reaction that is fire, and you have the fire tetrahedron. Remove one leg of this triangle/tetrahedron and the fire goes out.

Basic Extinguishing Agents
All extinguishing agents act to remove one of those legs:
  • Water mostly acts as a cooling agent, absorbing heat (especially when it turns into steam) and removing it from the fire, which makes it very effective at not only putting fires out, but making sure they stay out. Unfortunately, water is only safe to use on solid fuel fires.
  • CO2 acts as a smothering agent, displacing oxygen and removing the oxidizer from the equation. Just be aware that CO2 extinguishers build up static electricity, and thus must be grounded prior to use. 
  • AFFF (Aqueous Film Forming Fluid) and equivalent can be used as a cooling agent like water, or as a smothering agent for liquid fuel fires. In both uses, it works to help keep the fire out, limiting the risk of reflash
  • Dry chemical extinguishers interrupt the chemical reaction itself. If you acquire no other extinguishers, a dry chemical one is probably the one to go with, as most of the time dry chemical will be effective. If you own a fire extinguisher, it's probably a dry chemical one; they’re the most common, the cheapest, and work on most fire types. At the prices they sell for on Amazon, even on the high end, everyone should have at least one, even if you don’t have a boat. When using dry chemicals, be aware that they’re very irritating to breathe, and are usually highly corrosive, and electronics will need to be detail cleaned or replaced. Even if you avoid any smoke inhalation, dry chemical will make you wish for breathing protection. 
  • Fire blankets aren’t technically an extinguishing agent, but they’re a very useful and inexpensive tool, and can be used to smother some small fires. 
You should have extinguishers in all spaces where cooking, engines, gasoline, oil, poorly managed extension cords/power strips, and dryers may be found. 

Fire Types
There are four classes of fire to be concerned about, and each of them is fought in somewhat different ways, (mostly) using one of the above listed extinguishers.
  • Class A (Alpha): These are the basic solid fuels: wood, cloth, dried paint, pipe insulation, plastics, etc. Water, AFFF, and dry chemical extinguishers are all effective. 
  • Class B (Bravo): These are liquid and gaseous fuels: propane, gasoline, kerosene, etc. 
  • Class C (Charlie): Electrical fires.
  • Class D (Delta): Metal fires (and not just magnesium, either; even iron can burn under the right conditions).
Fire Alarms
The first thing you do upon discovering a fire, regardless of size or type, is to announce that there is a fire and the rough location of that fire in the loudest voice that you can manage, and using a PA or internal mass communication system if at all possible. Do this even before attempting to fight the fire! Quite frankly, fires aboard a ship are too dangerous for you to take the risk of being overcome by the fire prior to warning others.

Do not attempt to fight large interior fires. If you can’t put a fire out quickly, evacuate and do not attempt to fight it. Becoming a Screaming Alpha is one of the less pleasant ways to leave life, and smoke inhalation isn’t much fun either. If you have any dependents that are unable to evacuate, or whom cannot be trusted to evacuate on their own, that should bias you towards evacuation rather than fighting the fire. Lives are more important than things, so do not risk the lives of others to save your boat. 

Fighting Fires
When it comes to actually fighting the fires, there is some divergence. Most extinguishing agents will work on Class A fires; water, AFFF, dry chemical, and (for smaller fires) fire blankets are all effective. Just follow the directions on the extinguisher for using it and aim at the base of the fire.

Class B fires are a bit trickier, as water and CO2 are not options, and per at least one study from the Netherlands, neither are fire blankets. If the fire is contained in a cooking pot, put the lid on it; otherwise, AFFF and dry chemical should be used. AFFF should be applied not directly to the fire, but rather by bouncing it gently off of something else onto trying the burning liquid; the reason for doing this is to avoid splashing the burning liquid around while still covering the entirety of the flammable liquid with foam. With dry chemical extinguishers, use as you would with a class A fire.

The best way to fight a Class C is to turn off the power so that it becomes a class A fire. This not only makes it easier to fight the fire, it removes the initial source of the fire too, so that it won’t start the fire right back up after you put it out. Know the electrical system of your craft, and what to do to secure power to electrical equipment quickly. If you can’t turn off power, you’re going to be using CO2 or dry chemicals to fight it. 

If you’re unlucky enough to encounter a Class D fire on your ship, be aware that none of the common extinguishing agents are recommended for use on such fires. Jettison the fire if at all possible; if that isn't possible, then abandon ship. 

At the risk of sounding like a broken record, keep in mind that extinguishers are not meant for fighting large conflagrations, and saving people is more important than saving things. If you could reasonably say “the room is on fire” instead of saying “that pile of oil soaked rags is on fire” it’s time to make like Brave Sir Robin and bravely run away. Even if you’ve got a Self-Contained Breathing Apparatus (SCBA) and full Firefighting Ensemble, you probably won’t have a team of trained firefighters helping you -- and if you do, and you’re not a trained firefighter, get out of the way and let them do their job.

If you successfully put the fire out, congratulations! You’re not done yet, though. Now you get to sit there with an extinguisher and make sure it doesn’t reflash until the firefighters arrives. This is especially important with CO2 and dry chemical extinguishers, because once the CO2 or dry chemical clears out, the fire will quickly resume burning if the fuel is still hot enough. Regardless, just because the fire is out does not mean it will stay out, so keep a weather eye on it until the professionals take over. 

The Most Important Thing
In the end, the most important thing is detection, followed closely by preservation of life. Having all the right knowledge and  extinguishers does you no good if you don’t know about the fire. Even if you do have the knowledge, err on the side of caution, and don’t try to fight fires that are beyond your capability. A boat can be replaced; a family cannot.

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