The Offshore Voyaging Reference Site

Fire Control


A fire aboard ship has to rank near the top of the “Things that Terrify Skippers” list. Fire is rare enough, and scary enough, that many of us might prefer not to think about it.

Can we make a boat fireproof?

In short: No.

The closest we could get would be an unpainted, uninsulated aluminum boat with no interior and no powered systems. Pretty much all wood-based products, most composites, most plastics and most fabrics are at least somewhat flammable under some conditions, not to mention the fuel for the engine and the stove.

We can, however, do a pretty good job of preventing a fire from starting, and if it starts, preventing it from spreading. These prevention measures form the single biggest component of the ABYC rules and the rules of the various class societies. There are far too many of them to repeat here, but they basically boil down to: Install equipment properly and never cut corners.

Even on a perfectly rigged boat, though, accidents can happen. If a fire does break out, you’ll want to be prepared.

Extinguishing agents

We’d be mad to go to sea without a few fire extinguishers on board, and it’d be a fine idea to bring the correct ones for the materials on board our boat—there is, after all, quite a wide selection to choose from. Extinguishing agents are classified by the type of fuel they’ll work on. Fortunately for the globe-trotting skipper, these classifications are pretty close to universal.

Class A extinguishers will work on ordinary solid fuels, like wood and fabric.

  • Water is the standard Class A agent, but if used on a liquid fire, it will only spread the mess around.

Class B extinguishers are for liquid fires, such as gasoline, stove alcohol or cleaning chemicals.

  • Ammonium phosphate, also called “ABC Dry Chemical”, is the most popular choice of extinguishing agent as it works reasonably well on most solid and liquid fires.
  • Sodium bicarbonate, potassium bicarbonate and potassium chloride are also acceptable class B agents, but have the major disadvantage of being ineffective on class A fires.
  • Compressed carbon dioxide, which is often not a good idea for solid fires (the high pressure jet scatters the burning materials), works well on many liquids and gases. Don’t uncork one in an enclosed space, though: The oxygen-displacing gas just might extinguish you as well if it can’t dissipate quickly.
  • When diesel or gasoline are involved, it’s hard to beat the messy but effective wet foams favoured by airport firefighters.
  • In Europe or Asia, an additional class C rating means the extinguisher will work on gas fires, such as a propane stove.

Class C in North America, or an Asian E rating, is for electrical fires.

  • These extinguishing agents are non-conductive, so they won’t short out electrical systems near the fire or, worse, conduct electricity through the stream back to you.

Class D rating indicates a specialized extinguisher for metal fires, such as those that can be started by damaged lithium batteries.

  • No one type will work on all metal fires.
  • Sodium chloride, copper power and graphite based extinguishing agents are the most common.
  • If you use lithium batteries, you should have an extinguisher specifically designed for them. Regular ABC extinguishers will not put out a lithium battery fire!

Classes K or F indicate a dedicated galley fire extinguisher, designed to work very well on cooking oil and fat (although a class B will also work on these materials).

How big?

In North America, the “A” and “B” in an extinguisher’s rating will be preceded by a number. The number before the “A” describes the extinguisher’s performance relative to water; a 1A extinguisher is (very roughly) equivalent to a 1.25 gallon/5 litre bucket. The number before the “B” is the number of square feet that the extinguisher will cover before running out. (A full description of these ratings is defined in ANSI/UL standard 711.)

We can see that the common 1A:5BC extinguisher, carrying 2.5 pounds of ammonium phosphate, will be woefully inadequate for any fire that couldn’t be killed with one bailing bucket. Its double-size sibling, the five pound 2A:10BC, is perhaps a more appropriate choice; it packs enough punch to knock out a stir-fry gone wrong, or perhaps a cleaning chemical spill on the electrical panel.

For a battery, stove or tank top fire, though, there’s no substitute for the big guns: a 10 pound 4A:60BC or a 20 pound 20A:120BC. That last one is a $200 beast that stands two feet high, and is heavy enough that some lightly-built crew will have a hard time handling it. Several smaller extinguishers instead of a single monster one might be a better choice.

An engine room fire is another beast entirely. Even with the relatively cramped engine rooms of many modern yachts, you might empty a couple of those 20-pound brutes through the extinguisher ports in the hatch and still not kill the whole fire. Permanently plumbed fire suppression systems, which flood the whole engine room with a combustion-inhibiting fluorocarbon such as FM-200 or FE-36, are arguably the most effective way to control a major fire. On any boat with a price tag in the high six figures or above, you’d have an awfully hard time justifying the omission of such a system. They are, unfortunately, far beyond the budget of most of us.

Where should they go?

Let’s say we’ve settled on five- and ten-pound ABC dry chemical extinguishers—a popular and logical choice, albeit far from the only option. How many should we have, and where should we put them?

We’ll want an extinguisher at hand as we’re leaving each space that contains a fire hazard. That puts one at the entrance to the galley, one outside the engine room hatch, one near the battery bank, one near the electrical panel, one near the top of the companionway, and one beside the propane and outboard gas lockers. If we have a walk-in engine room, we’ll also want one or two in there. Fires grow incredibly quickly, and you might have only a few seconds in which to kill one; running to another part of the boat to get an extinguisher wastes precious time.

This little exercise also settles the question of “how many”. By the time you’ve put an appropriately sized extinguisher everywhere you would expect to need one, you’ve probably exceeded the number you’re legally required to have by a factor of three or more. Not incidentally, this means that a second person can always be ready with a second extinguisher in short order if the first one’s not enough.

How do you use them?

Now we get to the important part, and it’s the part I’m not going to fully answer. Instead, I’m going to say: Go talk to the nearest fire department.

The basic “how to” is something we all know. Pull the pin, aim at the base of the flames, squeeze the trigger, sweep the spray over the fire. You’ll have about ten seconds of spray time in which to either put the fire out or cut it back enough for a second person to get there with another extinguisher. But that’s far from all that we, as skippers and crew, need to know when we have no-one else to call on.

So go to the local fire hall or Coast Guard dock. See if one or two of the guys would mind swinging by your boat for a beer after work. Ask them things like “if this stove went up, where would be the best place to hit it from?” Or “How could I get this into the battery bay without opening the lid and causing a flare-up?” If you’re really feeling hardcore, ask them if anyone knows where you can take an STCW 95 shipboard firefighting course.

It’s also a very good idea to get some practice fighting fires in a controlled environment, so you won’t panic when you have to do it for real. The fire department in my hometown had a big shallow water tank on a trailer, with propane injectors under it, to train random civilians on how to aim and fire an extinguisher. I think every kid in the district had proudly put that thing out by the time they were ten years old. Failing that, it’s not too hard to set something up with a few old pressurized water extinguishers (cheap and easy to refill), a local extinguisher serviceman, a few friends, and a nice big campfire.

Hopefully you’ll never need to use it, but what’s $400 of equipment and an afternoon making friends at the fire hall compared to the possibility of losing the boat and everything on it?

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I don’t like the chemical ones(C). Using it, you will get a mess around. The powder will go to every part of your ship. You need weeks to clean it. Offshore you need external help. Air filter must changed, electrical contacts must be cleaned etc.. You will find the powder after years in hidden corners.

CO2 is a clean solution. After usage you must ventilate the rooms. With a free choice a would take NO2 for fix installed systems. You must ventilate the rooms too – but it is not toxic!

Best of your hint is: go to a fire stationand fire your questions.

John Harries

Hi Gerhard,

That’s a good point. On “Morgan’s Cloud” we have mainly gas extinguishers for exactly that reason. The exception is the galley where I was advised by a fire expert that a gas extinguisher will only make things worse. Also, I think I’m right in saying, gas extinguishers are generally not as effective against most fires that will occur on boats as dry powder (Matt?).

After reading Matt’s post I’m going to add a couple more dry powder extinguishers to backup our gas ones on the theory that it’s better to be faced with a horrible clean up job than have no boat left to clean up!

Erik de Jong

Hi Gerard,

I agree with you on the foam and the problems you get with the electrical system afterwards. But a CO2 extinghuisher is not from these days anymore, and unusable for a portable extinghuisher because you will kill yourself while using it. A better option would be to use bottled FM200, you could even breath that without dying or any other long term damage to yourself, and kit is better for mother nature as well.

In addition to Matt’s story, I would always want a permanently installed system in the engine room. Two or three bottles of FM200 or Novac with a pull cable attached to a bulkhead penetrating pulling station, each cylinder with enough capacity to smother the engine room completely so that you can repeat the action if the first charge did not kill the fire entirely. The engine room needs to be air tight to the boat’s interior, and prior to setting of a charge, the air intakes of the engine room need to be closed off.

And if you have to repaint the interior, buy intumescent paint or varnish, or low flame spread paint, and if you need to replace cushions or mattresses, make sure they are of “uncombustable” material. Curtains and other fabrics should be sprayed with anti combustion liquid. Those are non-poison, non- toxic, non-smell, non-stain liquids that prevent those items from catching fire. This needs to be done every year.

It might not save a boat from burning down, but it guarantee you some more time to take action since the fire will spread significantly slower.

Best regard,
Erik de Jong,
sy “Bagheera”

Colin Speedie

Hi Matt

Great piece, and good advice.

From my own experience with outfitting commercially coded boats in the UK, here are a few thoughts that might be helpful.

The big foam (13A/113B) AFFF units are effective, but most of them are not made for domestic use, not marine, i.e they lack proper securing straps. In order to install one below decks on Pelerin we had a proper mounting and securing bracket made in stainless steel to stop the thing from flying free and maiming someone in a knockdown. Unless you can find one with a proper bracket, think of budgeting to make one.

The engine room units you mention are indeed expensive – at least the good ones, with adequate capacity. The cheap ones are too small, and I’ve seen the ‘bubble’ trigger mechanism fall apart on one. The better ones with the combustible tube/fuse cable are expensive – but worth it.

A good quality fire blanket in the galley is a must-have, and required for coded boats.

I think it’s a good idea to have at least one bigger fire extinguisher in a cockpit locker – fire on a GRP/ply interior boat is going to release some seriously toxic fumes, and as the standard command is to get on deck as fast as possible, who’s going to hang around or return below decks to retrieve the fire extinguisher(s)? At least if you’ve got one safely to hand on deck you can buy some time with it, and get ready for your next move.

And I’d totally endorse your suggestion that attending a fire course is a good policy, not least because it makes you realise just how difficult it is to deal with even simple fires.

Best wishes


Ernie Reuter

Hi Matt….thanks for the great post. We also have a fire blanket close by to the galley, which in a pinch, would help to suppress a fire. It certainly would have to be used with caution so as not to endanger ourselves by getting too close to the flames but it is one additional weapon in the arsenal.
After reading your post, we will upgrade with a couple of extra 5 lb ers to complement the 2 that we already have…..thanks again for the seed plant in the brain…
Ernie & Bette
S/V Iemanja

Dick Stevenson

An excellent post. Thanks.
A few thoughts, not in any particular order:
The first thought notices that I tricked out Alchemy, to the best of my ability and budget, 12+ years ago in this area. Over years complacency kicks in and I find it harder to get energized to be on top of safety systems like fire prevention, especially since I have not been in home waters (familiar resources) for a long time now. It is easy to put off so your article will be a useful tickler for me.
Next, what do others do? We turn and tap dry chemical extinguishers monthly and (try) to get them re-charged every few years. We have thought about active “fire drills” but have never gotten around to making that happen. We have shot off extinguishers at fires at Safety at Sea type get-togethers.
The only 2 boat fires I have actually been near were both alcohol stoves. One was spread widely and dangerously by the introduction of solid water (small bucket). The other was neatly put out by using a shower bag (the black kind one puts on deck to get hot) and its shower nozzle.
The 2 serious boat destroying fires (I did not see, but came across after) were both owners who left their gensets going unattended.
We have regular household type smoke detectors in the engine room and above the electrical distribution panel in the saloon. So far nothing serious: with the latter, burned toast will give us a test run. The engine room will give us a bit of advance warning that the Eberspracher is starting to burn dirty or a fan belt is slipping. The alarm comes well before any human senses give warning which is re-assuring.
Again thanks, Dick Stevenson, s/v Alchemy, Hoorn, The Netherlands

Steve Hodges

Thank you for a well written and informative article.

Just as staying aboard is the best way to deal with crew overboard, the best approach to fire protection is to not have one! Effective fire prevention, like staying aboard, is a product of situational awareness and good practices. As the article points out, following safety standards is very important. So is common sense: separating flammables and ignition sources, maintenance of the galley, heaters and machinery, etc. But accidents happen so it pays to be prepared.

The choice of fire suppression agent is not a black and white one, and has been made more complicated by the shift to more environmentally aware practices, especially concerning ‘clean’ gaseous agents. The production of one of the most effective agents, Halon 1301, was banned by the Montreal Protocol because it is a significant ozone depleting substance (like Freons). HFC-227ea (DuPont trade name FM200) is a successful Halon 1301 replacement but has several drawbacks: approximately 40% more is required wrt Halon 1301 and, though it has no ozone depletion potential, it is a significant green house gas – pound for pound its global warming potential is about 3000 times that of CO2. FK-5-1-12 (3M trade name Novec 1230) has no ozone depletion potential and a global warming potential only a little higher than CO2, but a lot more of it is needed in order to be effective compared to FM200.
But both FM200 and Novec have a serious downside that is not often mentioned but well known to anyone that is trained to use them against a serious fire: toxic gas production. Both materials are heavily fluorinated and when exposed to flame temperatures their byproducts include carbonyl fluouride (COF2) and hydrofluoric acid (HF). COF2 is a cousin of phosgene (COCl) and, like phosgene and HF, a highly toxic gas. In a fire suppression scenario COF2 tends to break down into HF and other gases within a minute or so, but can exist long enough to be inhaled. The effects can be insidious: while in the excitement of fire fighting, inhalation of HF and COF2 gases may cause minor irritation and coughing, but several hours or a day later, serious, life-threatening pulmonary edema may occur. If you use these agents against a fire, and don’t have self contained breathing apparatus, hold your breath! The more challenging the fire suppression scenario, the more likely serious levels of toxic gases will form.

So what agent is the ‘best’ fire extinguisher choice? My choice has been to maintain my ancient Halon 1301 extinguishers as long as practical, which means until they are used or leak. The already installed replacements are dry chemical extinguishers, sodium bicarbonate for the galley and monoammonium phosphate for the engine bay. My reason for not choosing CO2 is the size and weight of the extinguishers, and the extreme variation of pressure with temperature. If I had a larger boat, I’d have CO2 extinguishers aboard. The risk of asphyxiation when using CO2 in a confined space is real but not as serious as some think: fires are more easily quenched by reduced oxygen levels than humans. I would certainly choose CO2 as a handheld extinguishing agent over FM200 or Novec.

Finally, I think it is wise to be wary of fire or flame retardant materials. This is current area of active debate and policy. The retardant additives are generally toxic and it is not clear that they are a net benefit, especially to those that don’t fall asleep on a couch while smoking. There is also a general tradeoff between flame retardency and generation of smoke and toxic gases: when exposed to fire temperatures, flame retardant materials produce more smoke and toxic fumes than the untreated material.

Steve Hodges
S/V Frolic


Matt – Thanks for the feedback. The answer to your question is ‘it depends.’ Fires and people are notoriously unpredictable. However, toxic byproducts are an inevitable result of the initial interaction of flourinated compounds and fire. This is also true for brominated and chlorinated compounds like the Halons. But unlike Halon, which has a significant chemical effect on extinguishing a fire, the fluorinated, clean-agent replacements (FM200, FE36, Novec) rely on their thermal properties to suppress fires. In the process of suppressing the fire, some of the fluorinated agent always combusts and produces potentially toxic gas. If the clean-agent extinguisher is challenged by the fire, more agent burns and more toxic byproducts are produced. Generally, the faster the fire is extinguished the less byproduct. How big a fire a person will fight, for how long, and how effectively depends a great deal on that person’s preparedness, training, personality and state of mind. The dose of the toxic cocktail an unprotected fire fighter receives will depend on all that plus whatever the devil in the details is, for example, what the air movement is. As suggested in an earlier comment, anyone really concerned about their ability to fight fires should get some training from a professional, the fire department or the coast guard. Steve

Dick Stevenson

Steve, When we started wandering more widely, I did some research (forgotten the details now) which indicated serious level fines in some countries if caught with Halon. I have no idea where things stand now. Thanks for the further details you provided. Dick

Steve Hodges

Dick – Thanks for the tip. I knew that halon extinguishers “may not be vented to the atmosphere during testing, maintaining, servicing or training. Failure to maintain equipment to prevent accidental discharge is unlawful” but wasn’t aware that possessing a halon extinguisher was unlawful in some countries. I will be sure to understand that issue before I leave the states. Steve


Great post Matt. That’s the clearest description of fire extinguisher capabilities I’ve seen.

What about use and location of fire extinguisher ports? Should we jam the extinguisher through and empty it, or use bursts, or sweep around? Are there guidelines for their location? Would adding one to a battery locker be a good idea for keeping out oxygen or a bad idea as maybe it would be better to open up the locker to help disburse the hydrogen?


Steve Hodges

I left two thoughts out in my original post:
– My comments regarding FM200 and Novec 1230 apply to FE36 (HFC-236fa), a halon 1211 replacement. FE36 has zero ozone depletion potential but, like FM200, very high global warming potential.
– The plastic brackets that often come with handheld extinguishers, as shown in the picture, are best replaced with robust metal ones – usually available as an option. And in the fine print, note that USCG approval is for the extinguisher when mounted in the metal bracket, not the plastic one! (I don’t know about other countries….)

Carolyn Shearlock - The Boat Galley

I’ve written several articles about fighting fires onboard over the past year and thought about it quite a bit. I’m thrilled to see your post and the Cruising Compass article on it as I think too many people simply put the extinguishers on the boat and figure that’s all they need to do.

One thing that really surprises most people who use a fire extinguisher in a real-life situation is how quickly they are used up. The typical size that’s on a boat is empty in just 10 seconds!

For galley fires, a fire blanket is actually of more use than a fire extinguisher, with the added benefit of no mess to clean up and no risk to nearby electronics.

But a real key is just to think through various scenarios and what you’d do. Not just how to fight the fire, but when to call for help (assuming there is help available), when to abandon ship, and when (if at a dock) to tow it away from other boats. A few of my thoughts — but I’m not an expert by any stretch of the imagination:

Love this discussion!

John Harries

Rats, rats, rats! Something else to add to the to-do list for this winter: complete inspection and analysis of our fire extinguishers. Matt, this is all your fault.

Well not all. Dick, you share some of the blame for your clear eyed admission and analysis of the complacency that can set in. I too went through the whole thing 10 years ago and have not given it the attention it deserves since.

And as for you, Steve, now instead of just saying to myself that all is OK because we have extinguishers that use one of the gasses that replaced Halon, I now need to actually think about which gas they are filled with—phosgene, who knew?

Seriously, thanks to all of you for a timely wake up call and some great information. Much appreciated! The combined wisdom that you three, and all of our other readers that comment, have is humbling.


To All Sailors,
I was in a boat fire and lucky to be alive. One thing that most owners miss is how fires get started. I have seen gas stored in cabins or in lockers with no ventilation. Why put your lives at risk ? Diesel burns but does not explode. Store gasoline (petrol) with common sense. All sailors need to use common sense too. Smoking even on deck can be dangerous. All the safety equipment is good but just be aware of how fires get started.

Erik de Jong

Quite a few accident have happened over the years, followed by almost as much investigation as to “how to”. Class societies have rules that dictate how a classed vessel is to be build. Fire safety is a huge issue in these rules.

Yachts however are seldom subject to such approval, but for a serious offshore yacht, I think it is worth while to read through the rules and implement anything from these rules on your own vessel that you realistically can, and a lot of accidents that you cant possibly think of in this stage, can be prevented from happening, of the risk thereof can be significantly reduced.

The rules are often published online and are free in some cases.


Some rules are easy to implement on an existing vessel, some are impossible or extremely expensive. But all in all, read it through, it will only take a couple of hours, and you will get some great ideas to make your own vessel saver.

Lars Erik Karlsen

Very importent article about fire onboard, but why is not Bontel mentioned?
A simple and cheap solution that kills fire when heat reach 90 dgr C without any damage. One glass ampull is enough in a room of 8 m3. You can easily put them in the engineroom, behind electric panels, together with batteries and so on. Works automatic and has 10 years warranty. Google Bontel and see for yourself.
best regards
Lars Erik

Brian Engle

At first glance, there is very little independent literature available on the Net about Bontel. Sounds interesting. Has this product been independently tested?



Thanks for the post. I wish more people mentioned fire prevention on the blogs and sites when they go about posting lists of improvmetns made to their vessels.

My own experience was with a fire on board an aircraft and let me tell you, when things get going it happens fast. In our case it was wiring that caught fire behind a circuit breaker panel which was eventually extinguished by removing power to the bus bar feeding the circuit and thanks to modern materials, the wire self extinguished after the power was cut . The whole series of events happened pretty quickly, and thankfully all was good afterwards. It was an adrenaline rush to say the least and what I remember most was the smoke. It was terrible, and took no time filling up the cockpit. The stench was unbarable, and the smoke caused so much pain to my eyes and nose. Can’t even begin to describe it. Sandpaper scraping you’re eyes might be close though. The oxygen mask and smoke goggles are for sure the only reason we all stayed in the game.

Which brings me to my own conclusions about heading out to sea. I would not leave port without some sort of smoke hood. These can be purchased for as little as $ 180 dollars from most aviation supply stores and have the ability to protect you’re eyes and give around 15 minutes of clean air. Life saving devices for sure.

As for our equipment. Each cabin has a hard wired heat/smoke detector with battery backup. Engine room has an automatic engine shutdown and fire suppression system along with heat and smoke sensors. Fire extinguishers are all halon and of appropriate size. But most importantly, every cabin has a PBE ( Smoke hood) and axe. Trust me, it’s seriously hard to fight a fire with you’re eyes closed. And sometimes you have to use the axe to punch a hole in something to spray agent ( i.e. you’re electrical cabinet or engine compartment. ). Smoke is serious. Much worse that the actual fire because the smoke is whats going to force you out of the tight quarters of you’re boat rendering you unable to fight the fire. Thus swimming in deep water or hanging out in the plush accommodations of you’re switlik :0)

That’s it for my rant. I’m not passionate about much with regards to refits, but I feel strongly about the above topic. Folks give this stuff a passing glance more often than not and it could cost them dearly.

Thanks for the venue to speak Matt.. Hopefully the story will resonate with someone.




Yachting Monthly did a video test on firefighting aboard their crash test boat. It’s a must see and an eye opener.

I was terrified by the dry powder. It can easily kill you!

Peter Mannerstråle

Hello John,
Have anybody used or bought this type of fire extinguisher?
Aerosol firefighter.
The are different sizes available from other manufacturers.

John Harries

Hi Peter,

I don’t have any experience with them, but it looks like a great idea. We still have a dry powder in the galley because our gas only (Halon successor) extinguishers are not rated for grease fires. I’m definitely going to look into getting one of these since I have always dreaded using the dry powder. I will still keep the dry powder as a backup but try the Maus first.

Anyone else have any first hand experience or insights into these things?

Thanks for the heads up.


I have taken part in a weekend-long seminar held in a training center operated by the Germany navy in Neustadt. This is to my knowledge the best such facility in Germany and their courses draw international participants. The German MRCC operator DGzRS also trains their personnel there. A substantial part of this training is hands-on firefighting. We donned heat protection clothing and masks and got close to the fire. The effect of heat protection suits is unbelievable. I remember a small burn I got from the radiation heat in a spot between the goggles and the mask. There is still a video around where I, together with one other participant, each with a 6 kilogramm dry powder extinguisher, managed to put out a fire of burning oil in a pan 4 metres by 4 metres, the flames from which were 5 metres high and with enormous radiation heat. We also tried an aerosol product.

My takeaway from this weekend re firefighting:

1. There is nothing nearly as effective as dry powder and go as big as you can
I once saw a camper van being eaten up by rust after a dry powder extinguisher was accidentally released in it for a few seconds. It’s only “harmless” baking soda but in a small space it works like tear gas and is horrendously corrosive. Because of that experience, I didn’t have one on the boat, thinking rather than ruin it with the powder, I’d just let it burn down and collect on the insurance. The problem with this thinking is that if you are at sea, it is only your heirs that can benefit from the insurance money (and in my case, my only heir would likely be on the boat with me).
With the burning oil pan I had a large 6kg extinguisher and so did my partner. If each had had half that size models, even an unlimited supply of these, we would have failed because if the fire is brought down most of the way and the extinguisher is out, it only takes 2 seconds of pause for the flames to be all the way up again.
On my boat I could not fit a 6kg model and we carry 2 half-size ones. One in a cockpit locker and one under the bed in the front cabin in case we have to fight our way out through a burning salon.
The test with the oil pan was in an extremely well ventilated special-purpose hall where overhead fans probably drawing 20 kilowatts were generating 20 knots of airflow. Inside my boat there would be way less oxygen so I hope to get along with the small extinguishers but if I ever had a boat built to my specifications, I would request space for two full size powder extinguishers.

2. Get a big fire blanket, not the small ones sold at chandleries
You can easily get fire blankets 6 foot by 5 foot. The price is nearly the same and not significant anyway. They work very efficient for many types of fires, not just a burning stove.

3. Carry an additional CO2 extinguisher of no less than 3kg if you have the space
They are effective for an engine room fire but not much else (if you use powder on the engine while it is running, you are probably in for a total rebuild). Don’t use them on a burning cabin as any fire creating ashes cannot be extinguished with CO2. If you have any doubt, try one on a campfire as we did. You can use up 20 large extinguishers on a normal sized wood fire without any noticeable effect at all. The flames are down while the CO2 flows but pop right back the instant the flow stops.

4. Avoid anything not listed above (except a bucket of water, of course)
During the firefighting training we tried a (water-) foam extinguisher and an aerosol generator on a bucket of burning oil. The foam had nearly no effect (suppressing the flames a little) until enough of the foam had returned to a watery state to collect on top of the oil to suffocate the flames. A 3kg foam extinguisher was barely enough to extinguish a bucket of oil and had the oil not been in a container (where water could collect), we would have failed.
The aerosol generator was laughable on the burning oil, probably giving 1% of the extinguishing power of a full size powder one. It seemed suitable to put out a candle but not much more.

There was some discussion with the instructors (which were excellent – instead of hammering the message down on us they showed us stuff and let us gain our own insights which turned out exactly the ones they wanted) about whether foam or aerosol extinguishers had some place on board of a boat (because they are so much easier on the boat) and the instructor’s message was:
– When you have a fire onboard, that is not the time to mess with toys and experiment. If you lose even only 30 seconds trying something that doesn’t work, those seconds could quite likely cost you your boat, and, if you are at sea, your life. In firefighting, a single second is a lot of time that can make all the difference.
– For the same reason, you can’t afford having to swap out the extinguishers while you work. Remember that you have only about 10 seconds on a 3kg small size and 20 seconds on a 6kg large size dry powder extinguisher and that you have to arm it first by depressing the plunger and waiting 3 seconds. Arm it when you have taken it from where it was stored and then use the 3 seconds to get in position.
– There aren’t normally “medium” fires on a boat. Most fires are either small enough for a swig from the beer glass you happen to have in your hand or they are too large to contain or nearly so. So don’t hesitate, act quickly and decisively.
– If you have an open fire that can be covered, use the blanket. There is nothing better so have multiple blankets and large ones.
– If you have an engine fire or contained in a small space with no wood involved, use CO2 (but it has to be a big one).
– In any other case, don’t hesitate to use powder and use it thoroughly.
– If you can be trapped inside, have an extinguisher by your bunk to be able to fight your way out.

So what I did is:
– toss my aerosol generator and foam extinguishers (I actually had to pay to have them disposed; in Germany, AFAIK, aerosol generators must be called “generators” because they couldn’t legally be labeled “extinguishers”)
– put one each 3kg dry powder extinguishers in the cockpit locker and under the forward bunk where we sleep
– put a 3kg CO2 extinguisher under the salon sofa (I would like a better place and bought a holder to put it next to the garbage under the sink but this is not done yet and a close fit, if it fits at all)
– enlarged the “fire port” hole in the engine access cover (which are the companionway stairs on our boat) so that the funnel fitted to our largeish CO2 extinguisher will fit through the hole
– have smoke detectors in all 3 cabins
– apply extra care to avoid chafe on electrical cables and generally do first class work in this area
At some point I would like an engine room fire alarm and automatic CO2 extinguisher.

John Harries

Hi Henning,

Very interesting, useful, and clearly well informed, thanks. I’m certainly not thinking of retiring my dry powder but I do think that having a small and less destructive extinguisher close to hand for say a small oil flare up on the stove might have value. Maus have kindly agreed to send me four of these units to have a look at. Of course I’m not qualified or equipped to do an effectiveness evaluation, but I will report what my impressions are in due course.

Peter Mannerstråle

There is a test done in Sweden where IT shows to as effectiv as a 2 kg powder. At that test they also tested a spray can with a fire retardant and that totally failed. See if I can find it (but it’s in swedish).
John cool that they send you 4 to test.

Peter Mannerstråle

Hello John,
Got two at the boat show in Stockholm this weekend.
They will probably make a larger version but I don’t know when that be on the market.
Also they told me that Volvo will put them in all new cars.


John Harries

Hi Peter,

Good to hear, the company inform me that they sent us the samples last week.

Rob Gill

Most interesting update thanks Henning,
A couple of thoughts as it applies to yachts – perhaps consider moving your CO2 extinguisher to the cockpit locker, and the second dry powder under your sofa? Having a CO2 extinguisher in the accomodation or anywhere that can drain to it is not allowed under Offshore Cat 1, or coastal Cat 2 regs. CO2 being heavier than air, can and has leaked from faulty bottles – but on the bright side you wouldn’t wake up to know about it !
Also, have you seen the Yachting Monthly “Crash Test Boat” on fire fighting:
This video highlighted for me an important issue that dry powder extinguishers present in a confined space, with both visibility and breathing problems if used without a breathing apparatus. Would that affect the views above Henning, given most of us won’t have a BA? Even with a smoke mask to aid breathing, would the reduction in visibility be more of a hamper in a small space than a help as the video suggests? It would be helpful if you could comment on the environment your training was conducted in – outside or inside? And if inside, how confined a space?


Hello Rob,

yes, it has occurred to me a few times that pressurized CO2 presents a danger and I don’t know of a good CO2 gas detector (the ones for propane/butane consume a lot of power and are prone to false alarms). Moving it to the cockpit locker will not help as that drains into the hull as well on our boat (a French plastic mass production boat). It would really require a second gas locker and there is no space for that. While in Spain I carried a blue Camping Gaz bottle in the chain locker (the only other safe space for gas) but it turned into a blob of rust in about 2 weeks even though I kept in plastic bags.
I have so far chosen not to act because I see so many CO2 extinguishers around. In my current place of work there is an extinguisher outside the IT room and there is also a 10kg CO2 bottle for a drinking water filter and carbonizer. If there were frequent accidents with these, I thought I’d know about it.
However, you are certainly right that it is a danger on the boat as the hallways in my office have better ventilation than my boat and also no one sleeps there.
My guess is that I would have to ditch the CO2 extinguisher and then what do I do in case of an engine fire?
Don’t the automated engine room fire extinguishers use CO2 as well? If so, are they illegal under the Offshore Cat 1, or coastal Cat 2 regs?

I was in the camper van when the dry powder extinguisher was triggered (in fact, I caused it moving stuff around) and I coughed my lungs out for 10 minutes and couldn’t see from tears for almost as long. So I see your point. However, I would state that dry powder is 10 times more effective than anything else, including CO2 (except maybe 20 tons of water). In case of a serious fire, I believe it’s your only chance to save the boat. There will be serious damage, some of which can be cleaned up, some not, but at least you still have a floating platform from where you can call for help.

I have a breathing mask with filter for VOCs and dust that I use for antifouling. This one doesn’t cover the eyes but I have seen ones that do. These are not really expensive and I guess, I’ll get one or two and tape them to the dry powder extinguishers.
True also that you won’t be able to see through the dust but I have spent so much time on my boat that I can move around safely when blindfolded. Remember that a 3kg powder extinguisher goes from full to empty in 10 seconds. It’s also the only type that will work when you are 10 feet away from the flames. With CO2 you need to be no more than a foot away. I don’t think that you can extinguish a major fire in the salon through the companionway while remaining outside but if it is possible, then only with dry powder.

Don’t get me wrong: I don’t dispute the drawbacks you mention but can’t see an alternative.

The fire training was part of a weekend “Safety at sea” seminar Friday evening to Sunday afternoon that also included medical instruction, dealing with hull breaches (no so helpful as it was geared to steel navy ships) and life vests and life rafts (each participant was issued one automatic life vest to test and there were one 6 person and on 12 person raft to inflate and use in pool with wave generator).
Wikipedia has this description of the facility (sorry, no english version):

The “fire hall” is also the training center for firefighters in northern Germany. It is indoor but, because of enormous fans, better ventilated than outdoors. This is a shot from a movie another participant made of the large oil pan:

I never had my eyes opened so often in such a short time and it was the best money I ever spent on any course. It’s not really an option for US inhabitants but there are often participants from Scandinavia.

Do you have a sprayhood on your life vest? We did a test with and without in the wave-pool. On the test without, the woman who volunteered shouted “stop” after the first wave crests washed over her face and she had gulped a lot of water. 5 minutes later, with the sprayhood on, the same woman was giving a thumbs up while 5 inches of water were over her face. And the instructors really brought home the point to us that you never enter a life raft if there is any way to avoid it.

Rob Gill

Hi Henning,
I have great faith in CO2 extinguishers (from personal use) to knock back fires and keep me safe fighting a fire at sea. Having done it in real life, the only thing I would trust more to enter an accomodation fire is a “water wall” spray delivered by a full bore fire hose.
So my view, no don’t ditch the CO2. We also have a production yacht – a Beneteau 473. Our cockpit lockers also drain into the cabin, but duct tape and two drilled holes to the cockpit meets our Cat 1 reqirement.
Totally agree, dry powder is best on oil fires, but is this such an issue on yachts? I am not so sure – we do not deep fry anything in the galley as it isn’t safe or healthy. Diesel is pretty inert except at very high temperatures or pressure, and is unlikely to catch fire. The petrol for the outboard is our single biggest FUEL fire risk except for LPG, which just tends to blow up!
CO2 is way better for engine fires and electrical fires. Foam in my experience is better for material fires like wood because of the duel smothering and cooling effect. They are also a good follower to CO2 in an engine room, oil or electrical fires (12V). We have one 3 Kg dry powder extinguisher for fuel fires, 2×3 litre foam extinguishers and one (small) fire blanket in the cabin. The 8 kg CO2 extinguisher is in a cockpit locker.

Finally, in the cabin we have a full smoke hood for each crew member, see:
We also keep a smoke hood in the cockpit, with our CO2 extinguisher and woollen flash hood (goes under the smoke hood) and a pair of leather gloves. I am looking for a boiler suit with a fire retardant coating and now a larger Fire Blanket – thanks for the suggestion!
Best regards,