The Offshore Voyaging Reference Site

Fire Extinguishers We Have Bought and Stuff We Learned

This article started life as a Tip, answering a question from a member, but then I realized that choosing the right fire extinguisher suppression agent is an important decision that warranted its own article. And an article tends to get more useful input from members in the comments. A good thing since I’m not an expert on fire fighting, or even close.

That said, I was advised by a commercial expert at Don Brenton’s Fire Protection with deep marine experience when buying new extinguishers for our McCurdy and Rhodes 56 a few years ago, and again when we replaced all the extinguishers on our new-to-us J/109, and I have just spent some time on the phone with them updating my knowledge.

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More Articles From Fire Safety:

  1. Fire Extinguishers We Have Bought and Stuff We Learned
  2. 5 Ways We Are Updating Our Thinking On Fire Fighting
  3. Maus Fire Extinguishers—A Breakthrough?
  4. Fire Control
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Rhys Walters

I had a welding fire on my boat, when a spark managed to find its way inside and land on some residual diesel that had soaked into the insulation. The worst experience i’ve had on board, and i got some pretty nasty burns while fighting it.

Your idea on having one in the Lazarette makes a lot of sense. After speaking with Bob Shepton re the loss of his boat up in the arctic to fire inside while he was outside, it would definitely be a wise decision.

Ken Deemer

In a recent post, you praised the benefits of the Maus Klein extinguishers. What would be the reason not to use them exclusively? I have purchased four of them for my 42 foot boat.

Pete Running Bear

You’re nothing if not thorough John.
I recently thew away all the old out of date rusty fire extinguishers that came with the boat. After a bit of cursory research I bought a load of ‘fire sticks’ and mounted them around the boat.

I was feeling rather pleased with myself for saving weight and space. But now you’ve introduced doubt.

I really don’t want to ‘get into’ fire extinguishers, I’m happy knowing nothing about them, so I ask the question rather reluctantly: are those fire sticks adequate? Does anyone have any knowledge of them? They’re the things you strike like a giant match and they spray a mist of water for about 45 seconds or so. The video shows them putting out an engine fire.

Matt Marsh

The legal requirement varies from country to country, but is generally along the lines of “you must have at least N fire extinguishers approved by agencies X, Y, or Z and their rating must be 5BC, or 5A10BC…” or something like that. You’re free to add extra equipment, but anything that doesn’t bear the rating specified in the regulations will not be counted towards your legal minimum during survey or random police inspection. The sticks to which you refer are not, to my knowledge, rated and certified; that said, I haven’t seen one in a few years and they may have been upgraded since.

Colin Speedie

I think the Fire Sticks are as explained here: – I saw some on display in a chandlery the other day.

Mark Ellis

Thanks for the article. As usual important stuff covered here.

I would like to know more about the CO2 option. Our engine room is sealed off from the rest of the boat so waking up dead is not such a concern (also, we can install CO2 alarms to be sure).

And a comment: We went mad with installing smoke alarms anywhere there might be smoke, especially electrical installations. And we don’t have gas on board (induction instead) which actually affords a great deal more peace of mind than I was anticipating.

Star Tracker

I wouldn’t like it in a fixed fire suppression system(not ABYC compliant), I do quite like to keep a handheld one as a sort of ‘nuisance’ extinguisher, one to use when there is time to get it, and limited immediate danger. Still keep the powder type mounted as needed, so anyone grabbing one in a true emergency will grab the right one. I like it for the following reasons:

1.It is environmentally safe, not probably safe, or safe until later research discovers how bad it is, and how hard to dispose of.
2.Exposure to Co2 is a known thing, with predictable outcomes, best to avoid/minimize but it’s effects are quickly noticeable even below levels that pose a danger. It makes no mess to clean up, won’t damage a running engine etc.
3.It rapidly cools whatever is sprayed with it. This is useful with certain types of fires, I’ve emptied one at another boater’s electrical system which cooled it enough to safely cut the wire he had badly burned himself grabbing in a panic, also an excellent trick with a half empty extinguisher when one really wants a cold beer without refrigeration available is to slowly blast the cans with it.
4.No risk of settled powder rendering it inoperable.

An example of the above in action: A friend decided that if #4 was good on my diesel stove carb, then turning it up past the numbers would be even better, despite clear instruction to leave it alone. They turned it so high that the adjustment screw was up on the top of the stop, resulting in a pot FULL of diesel and a rapidly increasing flame as it overheated the firepot. A quick shot of Co2 put out the fire, it was so hot that it re-lit itself immediately, I think a glowing bit of carbon was the cause. A slightly longer shot and it was cool to the touch and out. No mess, no cleanup, no unknown health hazards. Opened a few windows, siphoned the excess fuel out of the pot, and burner relit inside of 30 minutes. Debriefed everyone on board about the near miss. Refill was cheap, and done the next day.

Star Tracker

Felt I should clarify my point above about safety, should have worded it better. I’m not suggesting Co2 is safe to breathe, or trying to negate the hazards associated with it, it’s not accepted for fixed systems for very good reasons. The fact that exposure to it is something known and not uncommon, something smaller places with limited medical facilities will still be familiar with seems sensible to me, the lack of cleanup is nice too. I’ll be installing one of the modern fixed fire suppression options later this year in my engine space, but still feel that Co2 has benefits for small fires without creating a lot of mess, and being easily refilled and not part of the regular safety equipment means that having used it doesn’t reduce available options in a real emergency.

Do you carry spares to replace used ones until you can get them refilled? This year I got rid of the mixed sizes and standardized on one size of powder extinguisher, so that carrying one spare will allow me to immediately replace any used one.

Steve D

Where ABYC compliance is sought, CO2 is prohibited as a fixed fire extinguishing agent. Through the early 80s at least one large power boat builder installed CO2 engine room fire suppression systems, they were ahead of their time in many ways as most recreational vessels had nothing, and this was really all that was available at the time. There have been multiple deaths associated with these systems, in engine rooms, where systems have discharged while people were present. Today, there are better alternatives.

Matt Marsh

CO2 extinguishers work by displacing oxygen. If the total amount of compressed CO2 stored in a space is sufficient to bring the oxygen concentration below certain thresholds, then you are dealing with a “Confined Space” and need to add a lot of other precautions. For example, you can’t just go in there whenever you want to; you need gas monitoring equipment that verifies the actual oxygen level in the space before anyone enters. (Measuring CO2 concentration is not sufficient; you need properly calibrated and certified oxygen concentration meters.) And everyone who could potentially go in there needs special training on what to do if those gas monitors show an unfavourable result, or if their reading changes while you’re in the space. You also need to analyze where the CO2 will go when it leaves that space, and are you creating any more dangerous confined spaces in adjacent areas, etc.

For these reasons, the ABYC standards do not allow CO2 fixed extinguishing systems.

HFC-227, FM-200, and Novec 1230 are much better choices for a fixed engine room installation.

Steve D

John: In the photo of your engine room fixed extinguisher, how is the exhaust riser supported? I don’t see any support structure, stanchion etc.

I did a sea trial in Mexico last month, after running under moderate load for 20 minutes or so, I asked the owner if he would mind running the vessel up to full throttle. He said no, not at all, an advanced the throttle. A couple of minutes later I descended to the cabin and opened the engine compartment door, and was greeted with a face full smoke, through the haze I could see something glowing, that later turned out to be the exhaust insulation. The dry riser, which was unsupported (I had noted this earlier and included it my report), had cracked, and was emitting a jet of hot exhaust gases and smoke into the engine compartment, and now cabin. I’ve dealt with onboard fires before, something about which I never become complacent. I gave the order to cut the engine, the gasses had begun to set a hose alight. It’s a failure, cracked risers, I’ve encountered on several occasions. Many risers aboard sailing vessels in particular are cantilever designs, and as a result they lack adequate support. This is often exacerbated by hose connections that stress the riser and thus I also recommend that the hose between the riser and the muffler be made of corrugated silicone, this is softer and more flexible than black EPDM exhaust hose, and as such it places less stress on risers.
More on exhaust design here

Re. your very thorough and welcomed article, I have used smoke alarms in engine compartments for about a decade, they have saved users on many occasions in catching fires early, particularly when wirelessly interlinked to alarms outside the engine compartment. If your engine room is properly ventilated, smoke alarms should remain within their operating temperature range. I have nothing against temperature alarms, as an adjunct to rather than in place of an engine room smoke alarm. Most modern yachts have at least smoke, and often smoke and temp alarms in engine rooms. In the case of the sea trial vessel whose exhaust failed, had I not looked in the compartment that issue might have escalated into a full blown fire, one a temp alarm would not have caught until it was an actual fire. If there had been a smoke alarm in that compartment, I would have known there was a problem almost as soon as the riser had failed. I’m very surprised your professional fire system advisors recommended against using a smoke alarm in the engine compartment.

Most automatic fixed fire extinguishers are set to discharge at 175F, btw, of course no one wants to wait until that threshold is reached.

I’m a big fan of clean agent portable fire extinguishers, and specify them in and/or at the entrance to engine and engineering spaces, as well as adjacent to nav-com stations and inverters/chargers/batteries. However, they are not as effective as dry chemical units for a given size, often significantly less effective, and thus they should only be used in cases where the dry chemical is a liability, i.e. engines and electrical/electronics. Dry chemical extinguishers should make up the bulk of portable units on most vessels, with portable clean agent extinguishers placed near the aforementioned locations. Because it’s easy to grab the wrong extinguisher in the event of a fire, I recommend clean agent extinguishers be stenciled with large letters “CLEAN”.

There are new USCG portable fire extinguisher requirements, by the way, among other things I have detailed them here

Re over doing safety, I could not agree more, safety isn’t an end in an of itself, I like to say it’s part three of ‘seaworthiness, reliability and safety’, in other words the first two beget the third.

Finally, thank you for continuing to pound the ABYC drum. While I don’t agree with every line of every standard, it is an incredibly valuable resource that has made vessels more seaworthy, reliable and…safe.

Steve D

Any support for the riser must move with the engine, so that’s good. I suspected it might be hidden in the photo, I did notice the sensor for the wet exhaust temp alarm.

When I say “cantilever” to describe an exhaust, I mean essentially no support other than the flange connection to the engine exhaust manifold or turbo (and often the hose by default, but that can be counter productive as noted), those are problematic.

The features change so often it’s hard to select a particular brand or model and have it remain valid for long. First Alert and Kidde offer wirelessly interconnected models, and I have used units from both with good results. There others. More here, an article I updated in 2022

Alastair Currie

I use 2 x clean agent 2 kg automatic extinguishers in my engine space (only need one, other is redundancy) and 1 x clean agent 1.5 kg in the space that the diesel hot air heater occupies. The automatic mechanism is the break bulb type. They can be specified with different break temperatures, good to know if sailing in the tropics where a higher bulb temperature may be required.
At each exit, fore cabin, aft cabin and saloon, there is a 1kg Class A, B, C powder extinguisher. Also a central 5 kg ABC dry powder on the saloon table base facing the companionway hatch. I also have a fire blanket mounted opposite side of galley. All are formally inspected every second year.

I like the cockpit locker extinguisher and will adopt that idea, probably water mist P50 type, maybe portable clean agent, I’ll need to think about that.

In the UK there are P50 Service Free extinguishers (all types). They are designed to last 20 years and do not require the annual inspection and 5 yearly refill. Products inside are designed not to deteriorate or compact over this period. I think they are made from GRP or equivalent laminate tech. For commercial requirements they represent good cost savings. Suitable for outdoor locations, fully certified.

Recently, surveyors for commercial use leisure sector boats, have been demanding access points into engine spaces for a portable extinguisher. Previously the requirement was only for access point or automatic systems. The logic appears to be that if the auto system fails to extinguish, a small opening can be used to insert a portable extinguisher hose i.e. don’t open up engine room hatches and let in a large volume of air or evacuate the clean agent.

Other fire safety ideas, engine fuel shut off outside engine space, engine kill in cockpit, seacocks in engine spaces to be capable of closing outside engine space: wire pull or rod pull on a scotch yoke for a lever shut off. I have cockpit drain hoses in the engine space made from high temperature material. Made by Vetus, approved by Lloyds Register. To isolate air from a diesel engine consideration to fit a chalwin valve that will automatically and positively isolate air into engine if it starts to overspead. They just fit between air filter and manifold. See

Alastair Currie

No, I don’t have the engine room clean agents connected to a shut down processes. That is a good point and I will now review to see what can be done about that. Perhaps that is why the MCA now insist on the small access hole for the fire extinguisher hose. I agree about the chalwin valve, normal maintenance will eliminate that risk.

The P50S are powder, or other contents: –

Eric Klem

Hi John and Alastair,

With regards to engine runaways, I am not confident that most people would be willing to get in there and choke off the air intake. When an engine runs away, it is pretty terrifying, the noise is unbelievable and you are convinced that a rod is going to come through the block right at you. Given how cramped most engine spaces on cruising sailboats are, it is even worse as you might not even be able to properly reach the intake without exposing yourself to reaching over belts or taking the time to empty out an entire cabin to access some panel. By the way, many engines can run away for remarkably long periods of time before it gets catastrophic so while terrifying, you should act calmly.

My own experiences with this are with 2 stroke Detroits which are known for a few types of runaways not common to other engines but with the same results. The first is when the blower seals start to leak and force oil down the intake which results in effectively a normal runaway where the fuel is oil. The second is that an engine that has sat unused for a while can have an injector (unit injectors which are pretty rare) hang open which on the older ones would hang the whole injector rack on that bank and cause a spectacular fuel runaway. In all cases, a piece of wood or metal over the intake got the revs down to a low idle and then we could take the time to seal the last few air leaks and shut it down in a calm manner or drop it into gear which would stall it. There is a reason why a lot of the “newer” versions of these engines had intake shutoffs…

Having watched clothing go right through an engine, we used to keep a block of wood nearby that fit over the intake well. With our current boat and engine, I just don’t worry about it. The engine is naturally aspirated and doesn’t burn oil so the chances of a runaway are incredibly slim. In our case, the air filter is easy to remove and the intake is very accessible so we would have a decent shot at getting it shut down. Given how frightening they are, I would also not be adverse to using an extinguisher knowing that I was causing issues down the line. I doubt many people will have the mechanical know-how to get an engine that ran away back going again on their own without risking another runaway.

And a question. I have not seen mention of a fuel shutoff besides Alastair’s comment. I wonder if anyone has any evidence or calculations to suggest whether they are useful? I know that they are required on most commercial vessels but I don’t know if they really move the needle in terms of safety. On the one hand, there is huge fire potential in a fuel tank and if the hose burns through and a siphon starts, it could really accelerate everything. On the other hand, to get to that point the fire may already be out of control so it may not make a significant difference.


Eric Klem

Hi John,

I would bet that a foul weather jacket could indeed shut down the engine in most cruising boats if used correctly but using it correctly would definitely be tricky. The good news is that you can’t get a pressure differential greater than perfect vacuum so the pressures are not huge. The engines I had experience with were much bigger and capable of just eating stuff as the passages could pass large items and the valves, turbos and blowers could chop them up.

As for causes of runaway, I think there are a few we need to watch for. The most obvious one is leaking turbo seals on a turbo engine. When I dealt with high power turbocharged engines, I made sure to check the oil regularly for quantity and thinning and then also would take the intake off the turbo regularly and make sure that the shaft had virtually no play as once the bearings start to go, it will spray oil into the intake. It also makes sense to examine what is going through the intercooler regularly and if it gets noticeably nastier, it is time to investigate.

I know that a common cause given is poor compression but I am somewhat skeptical of this as being common. Yes, you do pull vacuum during the first stroke which could pull oil from the crankcase past the piston but I wonder whether the mixture coming into the cylinders will really be oil rich enough to cause a true runaway as most will still come through the intake. Maybe the engine won’t want to shut down or something but not rev at valve float? Out of pure curiosity, I would love to hear of actual examples of this if anyone knows of any, all the ones I have heard about ended up being something else. My suspicion is that the engine would be showing severe signs of low compression including very hard starting before you get to this point.

One scary one is external fuel sources. Assuming that we are not downwind of a chemical disaster, the fuel sources I can think of would be a propane leak or a gasoline leak. This is easily mitigated by proper stowage lockers and sensors so a well maintained boat shouldn’t worry about this.

It is also possible but highly unlikely to run away on your own fuel. 2 stroke Detroits were notorious for this due to their unit injectors where the actual pumping of the fuel happens at the injectors so if the fuel rack gets stuck, you get stuck at full fuel. Mechanical engines with injection pumps would normally be easy to shut down by activating the engine shutdown, I don’t know if there are any designs where this wouldn’t work. On electronic engines, it would be an electrical fault and hopefully shutting off the key would do the trick. If that doesn’t, it would get ugly fast as just shutting off the battery switch is unlikely to kill it as the alternator would still be providing power.

By the way, in road going vehicles with manual transmissions, the most effective thing to do is usually to hope you are in a high gear and then stand hard on the brakes and hope the clutch doesn’t slip. If you stand too lightly, the brakes will overheat before you stop and then you won’t be able to stop. I once received a panicked phone call from a friend doing 120+mph in a pickup truck wanting to know what to do (everything turned out okay, he had a fuel runaway due to a cruise control malfunction but he had already burned up his brakes).


Drew Frye

I’m not going to comment on engine fires. Not qualified.

Some very low impact suggestions that are also very, very effective.

Fire blankets. Every galley should have one. I prefer wool to the very light fiberglass type, because they better protect the user. It should be map-folded so that it deploys instantly (they are usually miss-folded when packed new). Other than a lid, the best answer for galley fires and some incipient fires. Also useful for warming peole up, which is another reason ambulances carry them.

Distilled water and water mist. I use distilled water in a mist extinguisher for welding fires. Very common for welding fire watch because they do no damamge and are the most effective type on class A fires. Distilled water is virtually non-conductive and is rated safe around electricity up to 35,000V (IIRC). I understand they have some popularity on boats in the UK. Protect from freezing. Not for the engine bay, but very good for everything else. Distilled water is also very unlikely to damamge electronics, because it dries without corroding or leaving any residue. Do NOT recharge with plain water.

Drew Frye

In my home shop I keep a 1.5 gallon pump-up bug sprayer at hand with DI water. I have an RO in the kichen, so refills are free and there is no disincentive to spray a little. Sometimes I lightly wet an area before using a torch or welding near wood or other combustibles; with a light mist there is no mess or damamge.

Kurt Jonckheer

The reference link is in Dutch so you will need to run it thru some translate, however this system does not break the bank and seems (never tried it, fortunately…) acceptable results.

The MABO is a technically high-quality fire extinguishing product based on a unique non-hazardous liquid packed in a special bottle, which breaks automatically at the start of a fire without the intervention of persons. MABO is a FLAMARK patent, developed in our own laboratories where years of specialist knowledge and experience have been brought together. The combination of this unparalleled powerful formula in a bottle with a capacity of only 570 cc extinguishes all kinds of fires safely and efficiently within seconds.

Link ans specs –

It is mounted on top of our indoor Volvo Penta (internal Diesel on our Hanse 385)

Stein Varjord

Hi John,

I don’t know anything more about this, but I do speak Dutch quite well now, so I’ve tried to look a bit into it. I’ll see if I can find more, perhaps call them. I’m interested.

Anyway, it seems to be a fluid that partly turns into a gas. It’s said to be non damaging to nature, short or long term, to humans, electric equipment or machinery. What its fluid form can do to an engine is still worth investigating further. Certainly seems able to stop it, just hopefully not permanently. 🙂

It does kinda have a manual trigger: The container is meant to be grabbed from the holder and thrown at some hard item near the fire, like a wall, which will break the glass and start the action. I assume that doesn’t really satisfy the manual activation regulations. To that end, it seems easy to put a small hammer or so on a hinge, with a cable connected so one can break the bottle manually from a distance. That might be sufficient?

Ray Taylor

Hello John and thanks for another well done article. On Aurora we use predominantly Purple K dry agent extinguishers with a small clean agent extinguisher at the engine bay fire port and a fire blanket in the galley.  
The decision to rely on dry agent extinguishers was based past experience in the oil industry where I used and trained with it regularly (mostly but not all Class B).  
I’m not as concerned about residual clean up and damage from the dry agent. My perspective is that Elvis already left the building, your boat is on fire the most important concern is to extinguish the fire as quickly as possible. For me (based on experience and training) Purple K dry agent is effective with low toxicity and adds a small amount of protection from re-ignition.  
Simply, the damage or clean up caused by dry agent is minimal compared to that caused by fire.  This of course is my opinion.
Best to you,

Brian Russell

We have Amerex Halotron handhelds units all over Helacious-except in the galley. There we have a simple inexpensive 2.5lbs. Kidde Sodium Bicarbonate extinguisher, and a handy fire blanket. The Kidde is not “USCG Approved”, but no matter, we have plenty of approved units onboard to satisfy the most ardent inspector. My opinion is that the galley is the most likely place for a fire to start (frying fish and the wok tips and poof! flash fire) so I want an extinguisher designed for grease fires: sodium bicarnonate. Environmentally friendly, easy to clean and inexpensive. We also have several accessible “fire masks” which are disposable smoke respirators that may give one a few extra minutes to fight the fire and save the boat. Smoke is the worst part of a fire, especially an electrical fire. Being able to approach and actually apply an extinguishing agent without being overcome is very important.

Brian on Helacious
Currently St. Pierre

Paul Browning

I recently came across Elide Fire Balls being advertised and having never heard of them, wondered whether the brains trust manifest at might know.

Charles Starke MD

Dear John & Phyllis
Will a silicone cooking glove protect long enough to throw a small lithium battery (handheld vhf, power drill battery) overboard or should I get a welders glove?

Best wishes,
Charles L Starke MD FACP
s/v Dawnpiper

Charles Starke MD

Does anyone know how silicone gloves would be? I carry them for cooking and don’t have a great place to store welders gloves.
This is on my mind because of this article:

Charles L Starke MD
s/v Dawnpiper

Stein Varjord

Hi Charles,
I also don’t know, but I think what works with a hot kettle will work with overheating batteries. Welding gloves might be better, but the batteries don’t initially get as hot as stuff we weld.

However, lithium batteries have another more dangerous issue; the poisonous smoke they give off when hot. It’s really poisonous. That’s also true for LFP. If a battery is smoking inside the boat, just getting out ASAP should probably be first priority.

LFP will get hot and smoke a lot if something dramatic has been done to them, like a massive short or physical cell penetration, but will not really burn enough to make a proper fire likely. However, most lithium batteries in small appliances, phones, laptops, tools… can indeed start burning without any external influence, and that certainly is hot enough to start a fire.

Initially such a fire will be limited to the item burning, so removing it would save the boat, but may actually kill the person doing it. That smoke is seriously bad. Again, that’s also true for LFP.

Lithium batteries very rarely do burn, but I absolutely think it’s smart to have a strategy for handling it. I think gloves is one part of it, but some sort of mask is probably even more important. That same mask is also essential in any other fire fighting strategy. I think this has been discussed in another article here.

I think it’s smart to have rules for where and how any object with a lithium battery is located on the boat. If it starts to burn, would it be easy enough to detect, and could we solve it? Some advocate keeping it all in a fire proof metal box, but I don’t think that’s realistic.

Charles Starke MD

Great answer! I do have a fire hood but doubt I’d have time to put it on.
Best wishes
s/v Dawnpiper