The Offshore Voyaging Reference Site

Maus Fire Extinguishers—A Breakthrough?

For years now we have had six fire extinguishers on Morgan’s Cloud located as follows:

  • Forward cabin
  • Salon next to the companionway
  • Aft cabin
  • Lazarette (in case we get trapped on deck by a fire)
  • Engine room (large and activated by a temperature sensor)
  • Galley

And, while I don’t claim to be any sort of expert on fire suppression or, more to the point, fire suppression at sea, Phyllis and I have always felt that this gave us some good options to deal with most fires we could imagine.

All but one of the extinguishers are of the clean agent type—halocarbon gas, purchased in the USA in 2004—to avoid the mess and damage that the use of other agents such as foam or powder result in.

The exception is the galley extinguisher, which is dry powder, in keeping with the recommendation we received from the fire suppression salesperson, who advised that the chance of a grease fire reigniting after a clean agent disperses, disqualified the latter type.

And therein lies a problem. Human nature being what it is, I just know that in the event of a grease fire in the galley we would hesitate to use the dry powder extinguisher because of the mess it would create.

And said hesitation could be the end of our boat, and maybe even us, since speed of action is the number one contributor to a successful outcome in firefighting.

By the way, if you have never let one of these dry chemical extinguishers off—I did in a long-ago course—don’t underestimate the mess. It’s bad enough that you may regret that the boat didn’t burn to the waterline!

That Was Then…This Is Now

But then, last year, member Peter Mannerstråle left a comment telling us about a new type of extinguisher from Maus, made in Sweden, which packs a huge punch in a small package—equivalent to a 1-kg dry powder extinguisher, at least (see video)—leaves no residue, and is suitable for grease fires.

I was so intrigued that I wrote to the company, and they kindly sent us four units for evaluation.

I’m not going to go into a long dissertation on how they work. Rather, here’s a video on just that. Have a watch and then I will detail what I think the benefits are for cruising boats:

What We Like

No Hesitation

I mentioned it above, but I think it bears repeating: To me, the biggest single benefit is that, since we know that using the Maus will not cause any mess or damage, we will use it instantly on even the smallest fire, rather than being tempted to try and “manage” the fire with other methods, such as our fire blanket.

Reduced Re-ignition?

It would seem that, at least in an enclosed space, the chances of the fire re-igniting are low for as long as the retardant agent is smothering the area. Now that’s probably true of halocarbon agents too, but the Maus agent is visible, so we will be able to see if it’s dissipating, while we stand by with another fire extinguisher in hand, probably the dry powder.

Fast Deployment

One of the problems with conventional extinguishers on a boat is that they can become dangerous projectiles in a knockdown, or even just a violent sea state. Of course, the answer is a massive retaining mount, like the the ones we installed (see picture at the start of the post).

But that solution reduces the effectiveness of the extinguisher, since getting it out of the mount will cost precious seconds if a fire does flare up.

In contrast, the Maus is so small and light that we are happy to use the simple plastic clip mount it comes with, which allows deployment with a quick and intuitive grab.

Sure, the Maus might fly out of the mount in a really bad knockdown, but it’s so small and relatively light that I think that risk is worth taking in exchange for fast deployment.

By the way, while thinking about speed of use, it’s important that all crew are aware of the need to pull the black ring in the base to activate the unit before using the yellow button to actually set it off.


As I understand it, many gas-type (all but CO2?) clean agents produce poisonous gasses when used on an open flame. Apparently, this is not a problem with the Maus, although I really wouldn’t want to breathe in a lot of the stuff. But here again the visibility of the agent is an advantage, particularly in enclosed spaces. Here’s some more detailed information.


Andreas Norlin, marketing guy at Maus, who has been very responsive in answering all my questions, tells me that they already have distribution in place all over Europe and are in the final stages of appointing North American and Australian distributors. So sourcing should be a solved problem very soon.

Cost and Options

Maus have just announced a larger Grand model, which looks to be three of the original Klein models in one package.

The Klein goes for Euro 70 including VAT, therefore I’m guessing a price in the USA of a bit less than $100, and the Grand is Euro 200, so probably a bit over $200.

Therefore the Maus units are expensive when compared to small dry powder extinguishers, but certainly competitive with other clean agent units like Halotron.

And, when thinking about value, we also need to think about lifetime. Andreas tells me that, after 5 years, the Maus units should be let off (for practice), and then disposed of as a standard metal spray can.

Maus have also announced a nozzle that fits the Klein to use in cases where the fire is in an enclosed space that has a fire port.


Of course, I’m basing all of this on claims made by Maus themselves. But given that this unit is from Sweden where safety regulation is taken very seriously, and the unit has been around for a while now, I think we are reasonably safe in believing their claims.

So would I equip a boat with just Maus fire extinguishers? No, not until they have been readily available for longer and some real world experience using them for fire fighting in boats has been accumulated.

It seems that even Maus agree with this approach, since Andreas wrote:

We are positioned as a complement to existing fire extinguishers.

Also, it may be some time before agencies outside of Europe, such as the US Coast Guard, certify the Maus units, although Andreas tells me that they have hired a company to at least start that process.

So the question becomes, are the Maus units worth the money on top of a full inventory of other extinguishers?

Given the advantages I listed earlier in the post, I would say yes. To me, adding at least a couple of Maus Klein units and replacing them every five years makes good sense.

And to answer my own question in the title, though probably not a breakthrough for us in the offshore cruising world yet, who knows how far this technology will go in the future? I hear from Andreas that they are nearly ready to release a large automated system using the same agent that might work well for a larger yacht’s engine room.

Further Reading


I believe that several of our members have extensive fire fighting experience, so I would be interested in your thoughts. Please leave a comment. Ditto if you have a question.

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Steve Hodges

Hi John,

As I’ve been involved with fire protection for too many years, I’ll take the bait.

Note that aerosol extinguishers have been around a while and have been offered by major fire protection companies, though reviews have not been completely favorable…. For example see this 2013 Consumer Report regarding two (non-pyrotechnic) aerosol spray extinguishers, which concludes “Don’t Buy: Performance Problem”:

But the above cited report did not consider the Maus product or a similar pyrotechnically generated aerosol (PGA) technology. I am not familiar with Maus products (yet) but have worked with many different types of extinguishers and fire suppression agents. So I couldn’t resist reading the literature on Maus’ website to get a better detailed understanding of this product; the following are my current thoughts. Their demonstration video is pretty impressive. The following are my current thoughts.

The main items to consider for any extinguisher are 1) chemicals involved, 2) potential combustion byproducts, 3) fire protection category (ABCDK), 4) clean up, and 5) life cycle cost (useful life, maintenance, etc). Based on my experience with pyrotechnically actuated extinguishers, I’d add, 6) temperature of exposed surface and effluent.

1. The 1st thing I looked for was the chemical used in Maus’ PGA extinguisher. The chemical used is important in understanding both fire-fighting effectiveness, and safety of use. The best I could find on the Maus website was “potassium compound.” Potassium-based is a good thing as potassium compounds, for example the dry chemical potassium bicarbonate (KHCO3), trade name, “purple-K,” are generally the most effective agents by weight (except for solids, aka class A, fires), with only minor safety issues (eye and lung irritation). However, the PGAs are more complicated than a dry chemical extinguisher, and the Maus product is no exception. The Swedish paper referred to ( has this to say about potential PGA health effects (note the final sentence):

“The size of particles generated by PGA’s was measured and the distribution of size showed that the particles have the optimal size for depositing in our lungs. A study of related literature showed that rats had been exposed to a similar PGA’s, but with higher concentration levels and a long exposure time. There were no fatalities amongst the exposed rats and a few of them showed symptoms of pneumonia. Further studies of this subject are required to reach a conclusion on if and how dangerous the particles are to humans. The conclusion of this report is that a PGA-system should not be installed in enclosures normally used by people.”

Note that common dry chemical extinguishers (sodium or potassium bicarbonate, ammonium phosphate) are safe to use in occupied spaces (but you may cough).

2. Byproducts. When a fire suppression agent encounters a flame it extinguishes the fire by a combination of thermal quenching, smothering, and chemical action. For example, the extinguishing action of water is purely quenching. CO2 and sand prevent oxygen from getting to the fuel thereby smothering the fire. Most dry chemical, Halons and clean agents (eg, FM200) both quench and attack the fire chemically (the effect of Halon 1301 is 70% chemical and 30% thermal, while FM200 has roughly the reverse ratios). I think it is a safe guess that the Maus PGA has both chemical and quenching action. Any agent that acts chemically by definition produces byproduct, and that byproduct may be toxic. This is obviously a concern if the intended use in is a confined, occupied space, such as a boat cabin. The Swedish paper referred to ( has this to say about PGA byproduct (again, note the final sentence):

“An analysis of the compounds produced when PGA’s are activated showed that the level of CO2 is far below the IDLH-value. The CO levels are just below the IDLH-value and should be taken under consideration when installing a PGA-system. The NH3 levels ended up at double the IDLH-value and therefore should be a factor taken unto consideration when a PGA-system is installed. The recommendation will be that a PGA-system should not be installed in enclosures normally used by people.”

Note that common dry chemical extinguishers (sodium or potassium bicarbonate, ammonium phosphate) are safe to use in occupied spaces (but you may cough).

3. Fire Protection Category. I could not find the rating on the Maus website, so requested what that is, or is expected to be, from their contact page. Most potassium-based fire suppression agents are rated BC which means they are effective against fuel-type fires (grease, petroleum), and safe to sue on energized electrical systems. The missing A in the BC rating means the agent is not effective against fires fueled by solids (trash, plastic, wood).

4. Clean-up. This is important as pointed out in the article. While there seems to be little doubt that PGAs produce less of a mess than typical dry chemical extinguishers (and they are a mess!), the PGA is not a clean agent. The aerosol is, after all, a cloud of “potassium compound” particles; the small size of the particles makes them more effective than larger particles used in dry chemical extinguishers, so less is needed for the same firefighting effectiveness wrt the latter. So some clean-up will most likely be required in order to prevent corrosion damage, staining, etc. The Swedish paper referred to ( has this to say about clean-up after a PGA discharge:

“A fast clean up of enclosures exposed to PGA is important, if left untouched the PGA will bind moisture and create a sticky paste. According to professionals in the decontamination field, such clean up is fairly easy and is best done by vacuuming or wiping the exposed areas with a damp cloth. However PGA’s are new on the market and no such cleaning has never been done, studies on how to clean up decontaminate is therefore required.”

5. Life-cycle cost. Since the Maus extinguisher is based on a pyrotechnic, it has a defined useful life, similar to pyrotechnic flares. According to Maus, the life of their extinguisher is 5 years (6 years maximum). So about every 5 years, they must be discarded and replaced. In contrast, single-use (aka disposable) dry chemical extinguishers are allowed (in the US) a 12 year life (ref. NFPA 10, or OSHA 29CFR1910.157). For the frugal, this tradeoff may be an important issue since the Maus extinguisher is more expensive than a dry chemical extinguisher: if it is 2X more expensive initially, its life-cycle cost will be about 4X more after 10 or 12 years. Depending on the clean-up required (see above) the extra cost may or may not be a wise investment. The good news is that there appears to be no maintenance requirement for the Maus, whereas, it is standard practice (and required by most applicable regulations) to perform a routine visual inspection of dry chemical extinguishers (gauge, cylinder condition).

6. How hot is it? All pyrotechnics produce heat after they are activated. The pyrotechnic shell gets hot, and the effluent (ie, aerosol) may be hot. The Maus extinguisher is no exception, but I didn’t find anything specific on this in the website, for example, what is the safe distance from the discharge port? It appears they have packaged the device so that thermal effects are not an issue – as long as their shielding and quenching mechanisms remain reliable throughout the life of the product. This is probably a safe bet, but something to keep in mind. That said, I would want to understand the temperature of the discharge before releasing the device, especially near someone I liked!

Bottom line: The Maus PGA looks like a promising product but there are significant caveats regarding safety-of-use in normally occupied (especially confined) spaces, clean-up required, and life-cycle cost. Some of these concerns may be mitigated when additional information is available. In any case, until it has the requisite approvals applicable to your vessel, the Maus extinguisher should, as you point out, be considered a complement to approved extinguishers.


PS. In case anyone has an insomnia problem, here’re some extra credit references:

a) This is an overview of my view of important sailboat fire protection issues and approaches:

b) As an example of the effort that may be involved with developing extinguisher systems, this is a study of fire suppression agents for potential use in a specialized application, military ground vehicles:

Lars Erik Karlsen

Hi Steve
I wonder if You also know something about Bontel.
A 300×60 mm container to place in the engineroom or in the galley.
If a fire takes place it will explode and kill the fire when temperature go over 90 dgr celcius.
No cleaning and no damage afterwards.
Any comments?

Dick Stevenson

Hi John,
You mention Nest detectors. A quick search indicates they are “smart” in that they can alert a phone. I am a firm believer in smoke/CO detectors in the engine room and other strategic locations but have always used well-reviewed household battery operated ones.
Are there advantages to the Nest that I should be aware of besides the “smart” feature?
Thanks, Dick Stevenson, s/v Alchemy


> will explode and kill..

Quote slightly out of context, but I still don’t like the sound of that in the galley.. 🙂

Steve Hodges

Hi John,

I agree with your conclusion and comments regarding clean-up’s possible contribution to life-cycle cost differences. But I think there are also safety issues (inhalation effects) that are also TBD. Until the new certification and rating of the new extinguisher is complete, detailed conclusions are speculative.

As I said in my original post, I haven’t any 1st-hand experience with the Maus product so can’t comment on what they’re like authoritatively and specifically; my comments are general. That said, I think clean-up could be a real problem due to the chemical used (which we don’t know), and the fineness of the discharged particles (which means it will get in all nooks). The video shows that the Maus discharge into an open computer enclosure doesn’t cause immediate electronic problems, whereas the dry chemical they used did. But what about after days or weeks, especially in a humid environment? That appears to be TBD.

I have no reason to suspect Maus is doing anything but their best to offer a safe and effective product, and I am not implying that they are trying to mislead (more than any marketing does), but even very large companies make honest mistakes. For example, Honeywell recently developed a new agent (HFO-1233zd) that appeared to be a breakthrough, and they went to the trouble of getting the US’ EPA to list it as a Halon alternative (not an inexpensive process), and it was on the verge of being included in NFPA 2001 (Standard on Clean Agents). But after all that ground work Honeywell discovered that even though the new agent seemed to work well in basic tests, there were scenarios when the agent could actually burn! So they withdrew it from the fire suppression market (it’s still a good, environmentally-friendly blowing agent, and listed for that use).

You are correct that chemically active clean agents can produce toxic byproducts. Many clean agents are fluorinated and pose two inhalation risks: the neat agent itself can be a problem if the concentration is too high, and when applied against a fire, toxic byproduct is a possibility. The inhalation risk of the neat agent from a handheld extinguisher is generally not a problem because typically the volume of the protected area is large enough that the concentration doesn’t reach unsafe levels (defined in NFPA 2001), and there is some air flow. However, when a fluorinated agent is exposed to a fire some hydrofluoric acid and carbonyl fluoride byproduct is produced, and these are toxic gases. Fortunately very little is produced – well within safe limits – when the fire is put out promptly. But near the limit of the fire extinguishing capability – for example, against a large, fast-growing fire, or against a fire in a very cluttered area – more byproduct is produced, and that could be a problem, especially in a confined space with little air flow.

Sodium and potassium bicarb dry chemical extinguishers do not produce toxic byproduct and pose very few health risks. The particles are too large to get deep into ones lungs so, though breathing the powder may be irritating, no long-term effects are likely. On the other hand, aerosols are by definition very tiny particles, much smaller than typical dry chemical powder, and they are small enough to go deep into the lungs so the health risks are potentially greater. And, according to the Swedish report, PGAs can generate ammonia at high-enough levels to be a concern, especially in a confined space with little air flow. I don’t know if, or how much, these issues apply to the Maus product.

As is so often the case, the devil is in the details, and there isn’t much detailed info on the new Maus product. Their marketing video is enticing and I think it’s worth watching the progress of the new product. By the time Maus completes the certification tests and gets their PGA extinguisher listed by government (eg, EPA, EN-3) and 3rd party (eg, UL) agencies, we will know much more.

As you have made clear in several posts in the context of electronics, it’s not generally wise to be a beta tester. And that’s the phase the Maus PGA appears to be in – beta. Caveat emptor!



Hi John,

After reading your primary article on the Maus extinguishers, I contacted their Portuguese reps and bought two small ones.
We sailed this August from Barcelona to Sardinia on our lovely Sunbeam 44 cc which we have been constantly refitting for a cast off date of 2020, including a professionally rewired electrical panel and entire boat.
Motoring back towards Menorca after a problem free passage, our new electric winch began to smoke. I thought that that was very strange and upon investigating, opened the engine access panel to discover a small conflagration of burning wires. I grabbed the Maus, activated it, and with one small squirt the flames were out! The smoke produced was insane and we activated a pan pan and prepared for the worst. The coastguard actually upgraded us to a mayday until I called them and said that the flames were out.
After changing my shorts, I investigated the damage and decided to attempt to repare the damage. Stripping some 60 -70 burnt wires and rewrapping them with elctricians and self amalgamating tape. I advised the coastguard that we would attempt a restart, just in case things went sideways. We fired up the engine and the elctrics were looking good only to discover a huge fuel leak. We quickly killed the engine, and discovered that the electrical fire had burned a hole in the fuel feed tube going to the primary fuel pump and that fuel was being pumped directly onto the flames! After changing my shorts again, I repaired the fuel hose, tied the wiring well away from the pump and proceeded homeward.

thank god that we discovered the fired quickly, and that the Maus lived up to its claims. there was absolutely no residue to clean up besides the smoke damage and burnt wiring and tubing. Thanks again for sharing your wisdom with us.

Marc Dacey

That’s what I like about AAC, John. You write an article and the first comment goes twice as deep!

Ted Scharf

I agree that a way to put out a galley fire and minimize the mess is important. I like the fire blanket. The one I have is make in Maine by firefighters. And there are others. At one time it was a requirement for the Bermuda race. Although when I looked at their requirements for this year it was not there. But it still is in the OSR requirements. “A fire blanket adjacent to every cooking device with an open flame”. Just another option. And one that doesn’t cost a lot.

Marc Dacey

I’ve learned recently that part of the issue with fire blankets is related to technique. You have to essentially raise the blanket to eye level and drape it fully over (for instance) the burning pot on the stove. Just chucking it could indeed overturn the pot. This sums up the approach, and it seems safe.

Marc Dacey

I don’t disagree, John. But you need to have a fire blanket and also the proper way to use it before you can decide it’s not appropriate depending on conditions. My takeaway from that video is to hold it high and use it as a shield so that it fully covers the stove top. If you have to walk uphill to do, I agree, perhaps not the best choice.

Drew Frye

Coming from a career in oil refineries and labs, let me speak to fire blankets. I have fought many incipient fires in many circumstances, most relating either to welding or lab accidents. I’ve used all of the tools and never had one get away from me.

A fire extinguisher can be the right answer. But it should not be the first thing that crosses your mind. The first thing is consider everything that is involved in the fire and pick the best course of action. What is the fuel. Where is it going. What needs to be cut off.

As others have mentioned, once you set an extinguisher off inside a cabin you have to leave. They are ALL inconsistent with breathing in a confined space. This is a strong reason to consider other actions first; if the extinguisher does not get it, if it re-lights, or if a little fire gets in a hidden space, you can’t go into the fight the fire. Thus, I like fire extinguishers mostly for engine spaces and hidden spaces; not general use in the cabin.

Regarding cooking there should never be so much oil in the pan that you can’t place a lid on the pan. The lid should be on the counter, next to the pan. The cook should never leave a hot frying pan. The cook cannot break these rules. Finally, even if you are going to use a blanket (the best answer for 95% of galley fires) , put the lid on the pan FIRST. In Europe the instruction caution that the fire can soak right through a blanket and spread. I’ve seen this happen in refineries. Put the lid on first.

Folding. The blanket MUST be folded so that it falls open when you grab the top corners; think Z-fold, like a map. It should open instantly or it is wrong. Do NOT fold like linens. In fact, most blankets are packed wrong from the factory; open the package and re-fold it correctly.

Finally, a wool fire blanket and be used for personal protection and to limit the spread. Getting it wet first is a big help. If it is not on grease, consider throwing water on the blanket. And don’t forget buckets of water! Finally, remember that fire extinguishers do not cool the embers; the fire can re-light. Water is generally best for this. Get your clothes wet (bucket over head) and wear gloves.

Fire off-shore can be a real fight to the death. It is dead serious in refineries too. You have to fight hard and fast, using all of the available tools and keeping a clear head. The raft is not much of an option, so fight to win. This does not mean you should seriously endanger yourself, but you may need to get in there and act without hesitation.

Drew Frye

I agree, once fiberglass gets going you are done. Get out. That is a good reason to have a raft. But depending on where you are, the raft is the “best bad option.” And even so, the ability to fight a safe delaying action will make departure safer. No, it is not about the value of the boat. It’s insured.

Without question, my background and experience encourages me be more aggressive, but I am still talking about incipient fires. That is the whole point–to attack aggressively and fast while you have a chance. My concern with fire extinguishers is that they drive you out of the cabin. You may not have put the fire out. You may have hit the wrong spots. I have seen MANY fires rekindle from hot spots because extinguishers do not cool. But since you have been chased out of the cabin, you won’t know until it flares back up, which it probably will. I’ve seen a LOT of fires that were out with an extinguisher re-light. Very common. Thus, unless liquid fuel is involved, a bucket of water may be a much better choice, and you won’t run out. Water is also needed after the extinguisher to KEEP the fire out. Thus, one or several buckets in a cockpit locker are key tools.

Common sense and a clear head is required, and that’s asking a lot in an area where few people get meaningful practice. I’ve watched people do stupid things in a panic, and I’ve pulled people out of the way so I could do it properly. Different situation require different approaches.

We had one incipient fire on a boat caused by a PO wiring stupid. It was easily handled by ripping off the covering and using a wet towel. After that I did a wire-by-wire inspection.


Pot full of oil? Is deep frying food on a boat galley stove ever a good idea? Just sayin!

But I do agree with you that trying to put out a fire with a blanket seems pretty tricky on a boat. Next to a campfire? Sure. But on a boat I’m not going to hesitate to knock it out with as much fire extinguisher as I need.

I spent 9 years in the US Navy on board submarines. We were all intensely trained on firefighting because, just like on a sailboat, there’s no fire department to save you. Unlike a sailboat, there’s the added complication of not being able to abandon ship.

Steve Hodges

I completely agree that having a fire blanket on hand is very wise. They are cheap, light, small and effective.

A correction on life cycle cost statement above, I made an arithmetic error! My statement “if it is 2X more expensive initially, its life-cycle cost will be about 4X more after 10 or 12 years” should read “if it is 2X more expensive initially, its life-cycle cost will be about 3X more after 10 or 12 years.” Generally, if the ratio of aerosol/pressurized extinguisher purchase prices is R, then after the 5-yr lifetime of the pyrotechnic, the aerosol will require 2*R more money. At the end of the 12-yr handheld dry chem extinguisher’s life, the aerosol will require 1.5*R more expenditure.

Also, ammonia byproduct mentioned in the Swedish paper, if it us part of the Maus PGA effluent or byproduct, could add to any clean-up issues.

Gardiner L Schneider

As an Off Shore Safety at Sea seminar Coordinator for the Cruising Club of America, I have been at a number of hands on fire training sessions. The speed of the enlargement of a fire on a plastic boat, which most now are, is phenomenally fast, often doubling in size in less than a minute. Losing the meal on the stove or grill is a cheap price to pay for saving the boat and the lives of the crew. In most cases, a five pound class ABC dry powder extinguisher is a good first choice. Yes, they only last for about ten seconds, which is why John is wise to have several on hand, especially as any fire may reflash even though it appears to have been knocked out.
CO 2 is great, we use them in our practice sessions on the fire pan. One of the main reasons we use the CO 2 is that repetitive use of the dry chemical type makes it almost impossible to relight the fire for the next person in line. Think about that for a minute: the CO2 smothers the hot oil and cools it minimally, but it rapidly disperses into the atmosphere and allows us to immediately relight the fire pan. The dry chemical powder floats on the hot oil and makes it hard to relight unless we add a splash of a new oil and diesel mix.
For me, the same argument holds for electronics fires. The “C” in ABC can be thought of as standing for “Computer”, i.e. “electronics”. I have heard it argued by participants in our classes that one should only use CO2 on an electrical fire as the dry chemical will eventually attract moisture and form compounds that corrode the wires and circuit boards. If I can put out the fire with dry chemical and save the boat and the crew, I will buy all the new electronics with a smile.
Garry Schneider

Odd Arne Lande

An interesting theme that one will make every effort to avoid. Here is a lot of good knowledge and a deep dive in a complicated subject. A good point here is the particle size of the extinguishing agent and the dangerous gases that are formed when several chemical substances are mixed together in a fire. A few breaths can endanger your life. If one has the opportunity to have a getaway mask, the likelihood of a good second-hand extinguish and search in the boat increases. If such a mask also can be stored safely outside in a lazarette and with a fire extinguisher device, one can get into the boat if a fire occurs when one is outside. A fire-retardant dressing suit and a pair of gloves are also wise to look up there.

Odd Arne Lande

Yes, the problem lies in the impossibility of exploring and analyse the chemical cocktail that occurs in a fire. Different substances at different temperatures, and what binds to new substances give us by products phosgene and other bad Per- and Polyfluorinated alkyl substances etc.

So here one must take all cautionary rules and consider it dangerous. Fire gases are dangerous, the temperature is more controllable and it is noticeable. If you get the temperature down, the chances are greater for a successful shutdown. That is why you see firefighters cutting holes in the roof while the extinguishing is going on. If we do the same in a boat, we are on a right track before we abandon. A small axe and a crowbar to open hatches to get hot gases out stored outside together with a small Maus, a smoke mask and flame-retardant dress is the way i have chosen to do it. Instead of an expensive special mask, use a half mask for protection against organic vapor and particulate hazards together with a wool balaclava and your dive mask together with (no nylon) coverall and you’re your own firefighter. Obviously, one must not stay in an area with a lot of CO and low oxygen, but this helps for a quick action.

A fire in the Engine compartments can develop a lot. Sound insulating foam of low quality is used in many new boats, these contribute to an explosive development of fire and they are so porous that diesel can easily be soaked if the thin surface is damaged (that often is the case). When ordering our Boreal I specified a damping foam that has a better flame resistance, thick skin and a density 10 time higher. Focusing on fire safety is something we have to request as customers, by demanding better solutions. If no-one else does, the industry continues with cheap solutions. Competition considerations on price, and the ISO standard may not be in our favour.

Charles Starke MD

Hi John
This is super article and discussion. The respirator is a great idea but the McMaster link had many confusing choices. Do you have a recommendation for a respirator mask to get? Thanks!

Odd Arne Lande

If you have a good half-mask that filters organic substances, you’re on your way (everything is better than nothing). The mask should have the best filter for particle (P3) since the dust and aerosols can harm you, the Maus aerosols has very small particles. If we get the polluted air and the aerosols out fast we have less to clean. The best filters are combination filters that take class ABEK P3, and some take CO as well. One gets these filters for half masks, or the best one; full mask. An escape hood like this one is among the best:

Shelf life is 16 years on this with filter change of 8 years. The advantage of such a mask is large, it’s quick to use and protect the head. Having it back home the rest of the year together with your fire extinguisher give you more time and safety if fire start here. Or bring it with you on travel and accommodation in places where safety is not a top priority, then the night sleep will improve after setting up your own smoke alerts. – Smoke detectors in boats like ours are not a requirement, just a recommendation according to the ISO standard, but I guess all of us have added at least one.

I have a Maus easily available in addition to ordinary extinguishers, and one is packed with the fire safety bag in the Lazarette. The tool in that bag is to break up or tear down things if it´s needed to get to the source of the fire.

Rob Gill

Hi guys,
Below is what we have in the cabin, plus one hood in the cockpit together with CO2 extinguisher, wool flash hood, a fire retardant boiler suit and gauntlets. It is a Japanese manufactured carbon based filter in a full hood / use once format. The price point (NZ$) was such we afforded one for each crew member. I really like the 20 minutes exposure time – anything beyond that and we would be in the liferaft!

Charles Starke MD FACP

Dear John
The Mcmaster link that you gave.above is to all their respirators. Further choice of respirators on their site is very confusing. Do you have a link or model number to the specific one you use?

I’m wondering whether to get the Draeger Parat fire escape hood that was also recommended above. Does anyone have a comparison with the respirator mask or comment? The Draeger fire escape hood at first glance looks very professional and appropriate. There seems to be a separate wall mount that has to be ordered if you get the hard case.

I haven’t found any way yet to get a Maus fire extinguisher in the US. Have you?

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

Andreas C. Norlin | MAUS

Hi everybody!

I was asked last week to comment on some comments regarding MAUS and I apoloigize for the delay. I sent this to our Fire Consultant Andreas Wistrand (Fire fighter who works for us) last week but I can see that he has’nt replied yet. So just let me start by posting the reply I wrote to John:


Hi John!

It will create at most a small dust like cover, but you could easily blow it away. No corrosion problems.

The aerosol is toxic free.

The report is from 2008 (on our website which was a general report of the new technology). The product was launched in 2013.

Have a great day and thank you for a great article. Feel free to experience the power of MAUS Xtin Klein.



If you wish to see the latest test done by a magazine in Holland for our Dutch distributor Technautic please check the link:


When I started this project my main focus was the auto industry. So many cars on the road doesn’t have a fire protection system because it wont fit anywhere unless you install it in your trunk. With MAUS I saw the possibility in having a fire protection within an arms length.

We are marketing our innovation as a compliment to approved fire extinguishers and there is no standard to test our unit against at the present. There are however discussions in the EU Parliament to certify EN3-7 fire extinguisher in fire classes as low as 13 BC.

There is one more thing that makes the MAUS Xtin Klein unique and that is the white potassium based aerosol (the smoke). If for example you have a fire in closed compartment and you exhaust MAUS Xtin Klein into that compartment and let the smoke float in that compartment, there will be no more fires starting. The technology of MAUS Xtin Klein is encapsulation the burning particles so they dont start burning. That is an easy way to explain it.

When it comes to the boat industry this is also a huge market for our unit. Our motto is Always use MAUS First! That might save you a lot of money and time and might even get you back to the harbour by yourself (without having some other boat towing you to the harbour). If the fire is too big you have suppressed the fire and bought yourself time to get the big fire extinguisher (powder, foam etc). However as great powder is to kill fires it will certainly kill everything in it’s path (electronic devices, engines etc).

We are soon launching MAUS Xtin Grand (3x as powerful as Klein) and our Automatic Fire Supression System; EGO. It will be all up and running on our new website that will be launched with in a month on

We have gotten so many amazing requests and we are working with a company in the US to be able to supply the units for the North American market. For Australia and New Zeeland we have not had any progress so please feel free to inform any of your distributors to contact us.

I wish you all a great day.

Greetings from sunny Sweden.

Andreas C. Norlin

Andreas C. Norlin

Hi John!

Please download the MSDS for MAUS Xtin Klein for a deeper analysis.

You don’t have to use any respirator cleaning up.

All the best.


Brian Russell

Interesting discussion…We have a bicarb extinguisher in the galley. While it doesn’t pass muster with USCG regs and isn’t “counted” it is still very good on grease fires. But the question I have is: Where on earth is all of this grease coming from?? Perhaps a better solution to the grease fire problem is to cook differently. I only ever use at most 1-2 tbs. of canola or olive oil for any dish, use very lean cuts of meat and we never deep fry!! Steaming, sauteing and roasting/braising are so much healthier and safer. We also have a nice Kuuma grill on the pushpit rail…although not usable at sea. But who wants to eat greasy food at sea? Just some thoughts…keep up the good work!

Brian Russell

Hahaha, we have switched to so-called Canadian bacon (which probably doesn’t exist in Canada!), the 3″ round stuff. Far different, but much less messy than the strip kind.

BTW, that fire blanket made in Maine is unavailable to the general public except through fundraiser sales by volunteer FD’s…

Dick Stevenson

Hi Brian and all,
I have been witness to a few fires, fortunately on other people’s boats.
As to grease, I also will not do without bacon, but I would also like to say that I have been impressed at how little grease can make for a big intense fire, at least for a short period, and a short period might be all that is needed for it to spread.
That said, whoever is cooking, should always have a good idea of the stove-tops capacity for fire and mix that in with the conditions one is cooking in.
The suggestion of a water mist reminded me of an alcohol fire that had spread impressively in a short time. A quick-witted skipper used his salt water spray nozzle at his sink and quickly dispersed the alcohol (one of the few nice properties of alcohol that was common in stoves 40 years ago). Many of us have these spray nozzles in the galley (salt or fresh) and I now list as ours of our fire-fighting tools in my fire-fighting crib sheet.
My best, Dick Stevenson, s/v Alchemy

Dave MacD

Timely article for me, as I am looking to update all of my fire systems at moment. One recommendation I have had is for a water mist system ( They are ABCF rated and claim to work for oil and electric with effectively no cleanup as the mist is basically dry.

Seems too good to be true.

Any opinions on this?

Peter Mannerstråle

The original in that area are High Fog and yes it works but has to be installed by pros. High Fog is expensive but it works for the areas like switchgear, steam turbine(oil) ,server farms. Would work perfect in the enginroom.

Peter Mannerstråle

I was to fast for answer, the one you link to is portable.
HI-FOG that I refer to is only fixed installation.
Maybe HI-FOG patent for the nozzel have expiere or they have constructed the nozzel another way.

Odd Arne Lande

Water expands quite a lot when it turns from a liquid to a vapor. The density of water vapor at 100 C at atmospheric pressure is about a factor of 1600 less, so water expands by a factor of 1600 when it turns into steam at atmospheric pressure. Water mist provides effective cooling. When fire fighting additives are introduced, the effectiveness of water mist is improved. I have good experience with high pressure systems (over 70 bar) stationary mounted. Expedition ship M/S Origo use this system everywhere in the boat as a big safety feature, it´s a long way to get help when you are North around Spitsbergen.

Brian Russell

Another important design / construction consideration for stopping brief grease flare ups from catching the overhead or adjacent cabinetry on fire is the installation of stainless steel sheet on the surfaces surrounding and ,especially, above, the cooking area. The overhead (side deck) which is partially about 3′ above our stove has 3/16″ of spacers between the 20ga stainless sheet and the wood overhead. This helps prevent the wood from getting too hot during normal cooking as well,, and is very easy to keep clean. Do not store combustible cooking supplies behind or to the side of the cooktop.

Bill Attwood

Hi Drew,
Your explanation of the correct way to fold a fire blanket was a revelation. I opened one of ours, and as expected it was folded wrongly. I re-folded it as you described. Result? Perfect! I asked my wife to deploy it. She pulled the blanket from its bag, extended her arms wide, and it was ready to do its job. Thanks for this nugget of good advice. Now to re-fold the other blanket.
Yours aye,

Drew Frye

I think it is scary that they are folded wrong. Just weird.

Another tip. Most wool army surplus blankets are treated to fire blanket standards. I learned this when I started test some old stuff for an article. Kind of obvious…no? (There’s lots of fire in a war).


As the Maus units are not USCG approved, they won’t satisfy the regulatory compliance mandated in 46 CFR, so not really an option yet for consideration for us – we are frugal.

Curious, your picture shows a Badger model 5MB-6H standard ABC multipurpose dry chemical extinguishers with manufacture date of year 2005. You state your other five extinguishers are of halocarbon gas, purchased in the USA in 2004.

As fire extinguishers of this type are required to be hydrostatically tested or removed from service at a maximum interval of 12 years from the date of manufacture [NFPA 10], how are you handling this issue?

As portable extinguishers must be inspected and maintained in accordance with NFPA 10, Standard for Portable Fire Extinguishers [46 CFR 162.025.30-10.a]; which implies some form of manual inspection record [NFPA 10], what is your method to comply with this? We are thinking of opting for the simple tag method or maybe log entries? Only an issue if boarded and inspected by you know who.

We are in the same situation with the foreign purchase of our boat – with very old unserviceable extinguishers that are not even USCG approved. Hydrostatic recertification appears to be more expensive than replacement – is this what you have determined?

Charles Starke MD FACP

Mark Lenci suggested I check out this agent:

It has the potential to be the solution for extinguishing a fire in a space that the typical boater could not get into due to smoke/heat/atmosphere.
Any suggestions or comments?
Charles L Starke MD
s/v Dawnpiper

Steve Hodges

The Flameguard “X-Tinguish® FST” appears to be a ‘grenade’ type extinguisher, which means, for it to be effective, one must toss the unit into the protected space. This is OK in some cases, for example, if you’ve evacuated to the cockpit and toss the ‘grenade’ into the burning cabin. However, if a fire is fully involved in an enclosed space, like the engine compartment, and a hatch must be opened into it the space to use the extinguisher, this could result in a worsened fire, because you’ve allowed more oxygen to fuel the fire. The strengthened fire may burst towards the opening, posing increased risk to the fire fighter, which is why fire ports, by which one can discharge a handheld extinguisher into the machinery space without allowing in more oxygen, are preferred.

So-called ‘fixed’ extinguishers, mounted in the protected space, such as the old Fireboy types with thermally activated ‘sprinkler’ heads, like fire ports, avoid the risks associated with opening a hatch into a compartment where a fire exists. Automatically activated fixed aerosol extinguishers are available; For example, Stat-X makes a variety of them, including ones designed for small vessels:

(While I have some experience with Stat-X aerosol extinguisher used to protect the engine compartments of large ground vehicles, I have no experience with their marine products.)

Application of aerosol extinguishers is covered in detail in NFPA 2010 “Standard for Fixed Aerosol Fire-Extinguishing Systems.” Section 10.5 in the 2015 edition the use of aerosol extinguishers to protect uninspected vessels and pleasure craft. Free online access is available here:

Steve Hodges

Hi John,

Unfortunately, there isn’t one answer that applies well to all applications; the devil is in the details….

Carbon dioxide (CO2) and the Halons are attractive because they are ‘clean’ agents; they leave no residue. CO2 extinguishes fires mainly by displacing oxygen to levels where combustion can’t occur, so, since we have similar oxygen needs as a fire, it is dangerous for us to use in confined, or unventilated spaces. Halon works at much lower concentrations and doesn’t need to displace anywhere enough oxygen to pose an asphyxiation risk in order to be effective; its action is mainly chemical – it interrupts the exothermic combustion process with endothermic reactions which don’t propagate so the fire goes. You can think of it like this: Halons work on fire the way carbon monoxide (CO) works on us; as you know, CO is dangerous to breathe when there is plenty of oxygen available.

Halon 1211 (CBrClF2) is a ‘streaming agent,’ and the most common Halon handheld (in the western world), and, on a weight basis, is about twice as effective as CO2. Your fixed engine system is probably based on Halon 1301 (CBrF3), which is one of the most effective ‘total flooding’ fire suppression agents available. The downside of Halons, besides their potent ozone depletion potential (a general global concern), is that they can, if used against a large aggressive fire (eg, one that isn’t extinguished quickly), break down in into toxic gaseous byproducts (acid gases and carbonyls). Unfortunately, newer, more environmentally friendly fire extinguishing fluorinated agents appear to break down in the presence of a fire more easily than the Halons, probably for the same reason they are more environmentally friendly (short atmospheric lifetime)….

Dry chemical extinguishers are very effective, and good substitutes for the Halons in many applications (including on a boat), and they pose no health risk; their downside is cleanup. Concerns about residue and cleanup, I think, were among your main reasons for being attracted to the Maus aerosol handheld. The grenade style extinguisher might be a helpful backup asset on a boat, especially if tossed into the affected area after the fire was knocked down by a handheld via a fire port. As indicated earlier, I’d be very reluctant to open any access port or hatch into an area where I knew a fire was burning due to the fear of making the fire stronger and getting injured in the process.

FWIW, I maintain up-to-date dry chemical extinguishers that meet USCG requirements (mounted in quarter berth and forward cabin), but also keep my old (and well cared for) Halon extinguishers handy (one in cockpit locker, one in chart table opposite galley). In the event of a fire aboard, I plan to reach for Halon first. My engine compartment is protected by a thermally activated Halon 1301 extinguisher.

Fun and extra credit?

The US EPA tracks and lists alternates to ozone depleting substances, like the Halons, in the significant new alternative policy (SNAP), see and If an agent is SNAP listed, it means it has undergone an extensive review that addresses firefighting effectiveness and health issues such as whether it is safe to use in an occupied area. While there are several aerosols listed in the ‘Total Flooding Agents’ section (including Stat-X), I don’t see any listed in the ‘Streaming Agents’ section. And note that some total-flooding aerosols are listed as safe for use in occupied spaces while others aren’t.

A deep dive into how to choose a handheld fire extinguisher selection can be found in annex C in NFPA 10 (2018), “Fire Extinguisher Selection.” The checklist in the “Principles of Selecting Fire Extinguishers” is not long and worth reading. Spoiler alert: aerosol extinguishers are not (yet?) addressed in NFPA 10.

Steve Hodges

Hi John,

Regarding the “worry with CO2 was that a cylinder could leak and suffocate us as we sleep….” It’s possible but to the best of my knowledge it has occurred very rarely, and I’ve never heard of that sort of accident on a small boat (eg, cruising sailboats). I wonder if two different hazards are being conflated, specifically that of leaks into adjoin compartments after a discharge on a ship, and a leak from a handheld extinguisher on a small vessel? Casualties due to the former are known, whereas, I am unaware of any examples of the latter. For example, according to the “Death and Injury Incidence Report” section (Appendix A) in a 2000 EPA report [1] that included merchant and military ships, during the period “BEFORE 1975” to 2000, there was one incident in 1970 where the death of (12) crew was attributed to slowly leaking extinguishers. That, while tragic, indicates a pretty low casualty rate, and I suspect many more lives in that period were saved by onboard extinguishing systems. Also, getting back to application on cruising sailboats, since CO2 is heavier than air (about the same density as propane), it sinks and so is expected to pose more of a hazard on large vessels, that have occupied areas on several living levels in the ship’s interior, than on small vessels where everything is on one level, and air mixes more freely. Certainly, CO2 should be used with attention to the risk of asphyxiation, but I think that is reasonably within the capabilities of most boaters, especially ocean sailors. I hadn’t heard about the NZ marine regulation regarding CO2 use on yachts, and didn’t find anything on it in a quick search. Do you have a source for that? I’m interested….

[1] “Carbon Dioxide as a Fire Suppressant: Examining the Risks,” EPA430-R-00-002, Feb. 2000.

Regarding Halon having the same risks, I’d say to a far lesser extent, and I wouldn’t worry too much about that one, assuming reasonable maintenance. My reasoning is first that halon (and CO2) extinguisher leaks are rare; I bet cracked chain plates are far more likely. In addition to that, even with the huge variation in vessel details, it is reasonable to assume that there is less Halon aboard a given boat than CO2, where they are used. This is because halons (1211 and 1301) are generally more efficient than CO2 so less of it is needed per codes and standards. The relative risk of Halon being much lower than CO2 is further supported by Halon being ‘safer’ at higher concentrations in breathing air than is needed to effectively extinguish fires (ref. NFPA 12A and 12B), whereas, whereas CO2 requires concentrations much higher than safe breathing levels in order to be effective (ref. NFPA 12). Both Halons are heavier than air, but lighter than CO2, so stratification will occur, but be less intense than with CO2. All that said, users of halon extinguishers should be aware that breathing the agent at high concentrations (eg, near the discharge) can cause dizziness and other potentially disorienting effects, so should be avoided. The hazard of toxic combustion byproducts being produced during firefighting, which, as described earlier is possible from all fluorinated agents, should also be understood.

Rob Gill

Hi Steve, John,
The requirement comes from NZ regulations of sailing which are based on World Sailing racing regulations. Open the PDF here: You are looking for page 53.
We have a CO2 extinguisher in a sealed cockpit locker that doesn’t drain to the cabin. Our Cat 1 inspector explained the risk was the cylinder discharging from a rust pin hole into the cabin and instead, extinguishing a sleeping crew member on a low bunk. CO2 is pretty poisonous at fairly low concentrations in air, but I have wondered why we wouldn’t experience the chest tightness (as when free diving) and wake up? But the Cat 1 regs are absolute in NZ. You can’t clear customs, even as a cruiser without a current Cat 1 certificate, signed by your inspector.
On another matter, talk is we will almost certainly see the CAT 1 regs require preventers to be bow rigged very soon.

Steve Hodges

Thanks Rob, I hadn’t seen that. I’m curious if there have been accidents involving CO2 poisoning on yachts? Anyway, I think a brief answer to your question, “why we wouldn’t experience the chest tightness (as when free diving) and wake up?” is: it only takes part of the typical CO2 extinguisher contents leaked into a living area to greatly exceed the levels where one would have the ‘wake-up’ reaction, and if exposed in a confined space to the high concentrations needed for effective fire extinguishment, you’d be in a coma or dead before you awoke.

Just for ‘fun’ I ran a few numbers. A typical handheld CO2 extinguisher contains 5 lb (2.3 kg) of agent. Five pounds of agent into a 150 cu ft (4.3 cu m) space results in an average concentration of about 30%, a little lower than the minimum extinguishing design concentration recommended for CO2 (34%), and about twice the breathing level that can kill in a minute or so. The ‘wake-up’ reaction would occur for CO2 concentrations of less than 10%.* The same mass of halon 1301 released into the same volume, by comparison, results in a concentration of a little less than 8%, far above the minimum extinguishing design concentration (5%), and only a little higher than a safe breathing level (7% for 15 minutes).

Aside: We breathe in CO2 at 0.04% and exhale about 4%, and build-up exhaled CO2 in closed-up cars has been implicated as the cause of drowsy drivers that have accidents.

So a take-away is that the relative safety of halon over CO2 is large (a much wider gap than what I had intuited). So the NZ containment/separation rule makes sense. Luckily, it is very unlikely that a CO2 extinguisher would spontaneously leak, but still….

* CO2 toxicity is described in gory detail in appendix B in the CO2 hazards EPA report I posted a link to above.

Rob Gill

Hi guys,
Sorry for the delay guys – I am in Fiji waiting a weather window to help a mate bring his yacht home to NZ.
I have little knowledge about Halon so can’t comment, but again chatting with my Cat 1 inspector who is a wonderfully experienced sailor and engineer, the danger is rust pin holes in the cylinders which cannot be seen visually (being under the paint finish), just the same with dive bottles. I don’t know of specific CO2 bottle incidents on yachts in NZ. My understanding banning CO2 from accomodation areas is a proactive stance, given their higher risk and numerous CO2 incidents in larger vessels.
The only safe thing is to pressure test cylinders every few years, which means emptying the contents which you can’t do with Haylon. With CO2, the safety risk is much higher, but pressure testing is simple.
As for the NZ regulations of sailing John, yes, they were a marvellous check list for us (young and old) going offshore, administered by our volunteer safety inspectors who act as your safety inspectors, coaches and mentors – they are mostly just brilliant!

Rob Gill

Hi Steve,
Haha, liked your analysis. Our CO2 cylinder is 5kg – happy it’s in a sealed cockpit locker.

Dick Stevenson

Hi Charles, Steve and all,
Thanks Charles for bringing this device to our attention.
Steve, Thanks for your clearly well-informed comments and the suggestions I was unaware existed. When reviewing the information on line, it was for the engine room that I considered the X-tinguish FST to possibly be a valuable addition to Alchemy’s firefighting ability. This was, in part, as I am one of those without a fixed extinguishing system for the engine “room”. I do have a fire port, but the idea of the “grenade” and its potency strikes me initially as far more potent than my large halon-type extinguisher through the fire port. This may be naïve, but opening my engine room door to quickly throw in the FST and then slamming it shut again, may not allow in so much oxygen that the extinguishing action would be negated.
My best, Dick Stevenson, s/v Alchemy

Charles Starke MD FACP

Hi Dick
Unfortunately, a flashback caused by opening the engine room door can be overwhelming and disastrous. You may not be able to toss this in if you get overwhelmed by the sudden “explosion” of a flashback.
I like your fireport or having automatic extinguishers that are mounted in place in the engine room.
Does anyone have a recommendation for a fireport, and what nozzles (like the Maus fireport nozzle) will fit it?
Best wishes
Charles L Starke MD
s/v Dawnpiper

Dick Stevenson

Hi Charles,
Thanks for the feedback.
My fire-port is a hole drilled into the engine area sized to fit the nozzle of a large halon-type extinguisher located ready-at-hand (sized to flood the engine area). It is covered by a Lexan see-through cover (to confirm the fire visually when the smoke/fire detector indicates a problem) that is designed to swing out of the way when using the extinguisher.
Many years ago, for many reasons, I decided this was the wiser route to go for fire fighting than a fixed internal system, either automatically or manually deployed. Part of that decision was just plain the real estate in my engine area was so limited. The FST is far more modestly sized and it (or a similar product) might be a much more reasonable choice for a manually-deployed internally-mounted fire suppressant system that is fixed in the engine area. In this way, any opening of the engine area is un-necessary.
At first blush, the effectiveness of the FST and “grenade” type fire fighting equipment looks superior to the usual fire fighting extinguishers. I like the reports of their effectiveness at reducing temperatures among its other reported attributes.
I look forward to further information on this type of fire-fighting gear.
My best, Dick Stevenson, s/v Alchemy

Steve Hodges

Hi Dick,

While it could work out so that “opening my engine room door to quickly throw in the FST and then slamming it shut again, may not allow in so much oxygen that the extinguishing action would be negated,” it might also not work out that way, depending on the fire details. Fires in confined spaces are often limited by oxygen supply, and they might even self-extinguish in a reasonably sealed enclosure. I like your idea of a fire port that allows viewing and use of a handheld extinguisher. But note that a fire that appears to be tame can, as Charles suggests, quickly grow into a dangerous monster if it gets fresh air. As one who has been singed (in firefighting exercises), I would be reluctant to remove any barrier between me and an unwanted fire, and would attack the fire using the fire port with the best extinguisher I have on hand.

Charles Starke MD FACP

Hi Dick, Steve & John
How can you see into the engine room by the lexan viewimg port?
My light switch is inside the engine room, and a typical boat fire has thick black smoke, obscuring vision.
The small Maus extinguisher can be fitted with a small nozzle. Is this large enough for an engine room? Is there a nozzle that fits on the larger Maus extinguisher? Which engine room port is appropriate for either extinguisher? I’ll email Maus with these questions. Thanks
Best wishes,
s/v Dawnpiper

Dick Stevenson

Hi Charles,
My idea, luckily not tested, is that I might be able to see flames through the Lexan covered fire port and/or see thick black smoke: either way, I would consider it time for the fire extinguisher. My light switch for the engine area is on the outside. My port was drilled with a hole saw to allow the nozzle end of my large extinguisher to just fit: from memory ~~1 ¼ inch. At some point I would start to get reluctant to drill a larger hole.
My best, Dick

Charles Starke MD FACP

To Maus extinguishers:

The small Maus extinguisher can be fitted with a small nozzle. Is this small Maus extinguisher large enough for an engine room fire? Is there a nozzle that fits on the larger Maus extinguisher? Which engine room port is appropriate for either extinguisher? Thanks
Best wishes,
s/v Dawnpiper

Hi Charles, How large is the engine room? The Xtin Klein is roughly the same effective power as a 5 lb dry chemical extinguisher. A major difference however, is the added benefit of continuing to retard the fire as long as the potassium-based aerosol is in the air in the engine room.

Depending on the size of the room, and of course the size of the fire, the Xtin Klein may or may not be sufficient. Sometimes having two Xtin Klein units readily available is a good solution. Unfortunately we do not offer a fire port nozzle for the larger units.

The Nozzle Klein is just about a 1/2″ square at the tip and 10″ long in total.

Any other questions please don’t hesitate to ask.

Nicholas A. Gregory-Bernstein
NordFire Inc.

Chuck B

I’ve just received my order of Maus extinguishers. I’m not so sure about the mounting brackets provided, although I understand this may provide a deployment advantage, and I see you’ve mounted yours in the same orientation I had decided on. I’ll be curious to hear what your experience is over time with how susceptible these things are to jumping out of their brackets. 🙂



Dick Stevenson

Hi all,
In sharing the Maus with others I was informed of what looks to be a very similar product which can be found at I am curious whether anyone has experience with it. I am limited at my connectivity at present, so I am unable to poke around the web site and play their video.
My memory is not great, but I do not remember this product coming up in the discussions on fire extinguishers.
My best, Dick Stevenson, s/v Alchemy

Edward Sitver

Hi John,

I was intrigue by the Maus extinguisher and finally did some more digging. Looks like there’s now a distributor in the USA:

Nick at Nord Inc
‭1 (508) 444-2077‬


Chuck Batson

Ed, I can confirm – I purchased two from this source last year.

Dick Stevenson

Hi all,
Practical Sailor (April 2020) has a nicely detailed article on the Maus fire extinguisher (and its brethren) concentrating on its use and its particular characteristics as well as comparing it to more conventional extinguishers. The testing was done and it was written by frequent AAC contributor Drew Frye in his usual thorough manner. I learned a good deal that will be useful when I use my already purchased Maus extinguishers.
My best, Dick Stevenson, s/v Alchemy

Ann Bainbridge

There is a new North American distributor for Maus products in BC, My recent order came with this news which some might find useful?

“Our MAUS Grande (3 barrel unit) just met UL711 for a B1 marine fire – that meets with the America Coast Guard Standards! The unit has a B 1 rating. B 1 allows a boat owner to use just one extinguisher for under 26 feet and two for under 46 foot… “

Ann Bainbridge

Sorry, that link should have read

Dave Meindl

I was just looking at the Maus site to see about ordering some extinguishers as a backup to our current set of extinguishers. They also have a product that was not mentioned in this post that might be worth looking at called Maus Fire Stixx. They are small stick on pads that release potassium based smoke to kill a fire early. I’m thinking this might be a good addition inside the electrical panel or under the floorboard above the bilge pump. Any thoughts?

Chuck Batson

Hmmm interesting, I wonder how well that would work for an engine compartment.

I see now they also have a nozzle for the Xtin Klein which for me solves the dilemma of how to use it with the small fire port for the engine compartment.

Dave Meindl

I tried to comment in the Fire Control article but the comment window would not open (maybe that discussion is closed and I missed the party?). In any case, thanks to everyone for all of the enlightening information. We are going to upscale our fire fighting equipment from the 5 dry chemical extinguishers and fire blanket by adding 2 Maus units and a 10lb extinguisher for the engine compartment. With regard to the engine compartment unit, I’m not comfortable with the idea of having CO2 on board so I’m thinking of adding a portable FE36 extinguisher just for that purpose. I’m planning on mounting the FE36 unit in the salon. If that unit were to get a pinhole leak, does it pose the same sort of risk of asphyxiation as a leaking CO2 unit?


Fortunately leaks and inadvertent extinguisher discharges are rare (I’d hazard to guess that they are rarer than propane leaks), especially if the extinguisher is inspected regularly and maintained as required (eg, as given in manufacturer instructions, and NFPA 10). But leaks, even if very unlikely, are possible.
Assuming no fire, the risk due to the inadvertent discharge or leak of an extinguisher charged with a gaseous fire suppression agent (ie, FE-36, Novec 1230, Halon) into the living space of a boat are two-fold:

  1. Asphyxiation due to oxygen displacement, and
  2. Cardiac sensitization, thus risk of heart attack, due to inhaling the fire suppression agent.

The standard for ‘clean agent’ fire protection systems, such as those based on FE-36 (aka HFC-236) or Novec 1230 (aka FK-5-1-12), is NFPA 2001 which gives the details on how to calculate concentration in a given application, and safety limits. Carbon dioxide (CO2), covered in NFPA 12, is not considered a clean agent and ‘only’ poses risk 1, asphyxiation.
 A detailed look into the safety question associated with 10 lb of FE-36 , or any fluorinated fire suppression agent, finding its way into the boat’s living space, requires knowledge of the free-air volume of the cabin. I’ll use my 36 foot sailboat as an example. My boat’s documentation lists her net tonnage as 12. My understanding is that 1 net ton corresponds to 2.83 cubic meters (m3), so based on that, the air volume in my boat is about 34 m3. Applying NFPA 2001, 10 lb (4.54 kg) of FE-36 into a 34 m3 volume yields an *average* concentration of about 2%. This means only 2% of oxygen is displaced, which is a non-event, akin to going a few hundred feet above sea level. A 2% concentration is also much less than the 5-minute exposure safe limit (based on the threshold for cardiac sensitization) of 12.5% volume concentration given for FE-36 in NFPA 2001. 
Unfortunately the above analysis is misleading because the free-air volume of a lived-in cruising boat is likely significantly less than indicated by her net tonnage. Probably more importantly, due to the relatively high molecular weight of FE-36 (152 g/mol) wrt air (29 g/mol), the concentration will not average over the cabin volume, rather it will stratify, as propane does (in fact, FE-36 is a variation of hexafluoropropane). This means a the agent from a leaking FE-36 extinguisher will concentrate low in the boat, as leaked propane would. This means that, at low areas, eg, bottom bunks, the concentration could, in a poorly ventilated vessel, reach levels that exceed the cardiac safe limit, or perhaps, in an extreme, lower oxygen levels to unsafe levels. Additionally, the safe limit, as noted above, is for a maximum exposure duration of 5 minutes. Clearly, if the leak occurs while people are aboard and asleep the exposure time will likely be much longer, and I’m not aware of any guidance for longer exposure times.
John’s caution regarding the use of any fluorinated fire suppression agent against a fire is spot on: “When [exposed to a flame], get out fast.” Combustion byproducts are nasty and can reach unsafe levels in a confined space quickly.
Bottom line: the dangers posed by FE-36 is essentially the same for any fluorinated agent (Novec, Halon, FM-200, etc); they all have down sides. The good news is that extinguisher leaks and inadvertent discharges are rare, especially if the extinguishers are inspected regularly and maintained as required. Good ventilation would probably mitigate the risk of a leak quite a lot (got muffin fans?). The reason to have clean agent extinguishers aboard is that, when applied correctly, they are very effective at extinguishing fires (almost as good as Halon 1211 and 1301 were), and they don’t make a mess.  


Hi John,

You’re welcome!

Regarding gas detection, I don’t know for sure, but I expect a typical combustible gas detection system would not sense the presence of a clean agent. The reason is that combustible gas detectors either rely on actual burning of the gas in the presence of a catalyst that allows combustion at much lower temperature than normal flame temperature, or on infrared absorption. Clean agents obviously don’t normally burn (caveat: I’m sure what effect the catalyst would have, but I expect not much), and they absorb at different infrared wavelengths than hydrocarbon fuels like propane, hence I don’t think they’d be detected by available combustible gas detection systems.


Dick Stevenson

Hi John and all,
I have been talking with a local fire guy about Novec 1230. Some take-aways (compiled from random talks in the boatyard while both of us were working, so do your own research to confirm).
Novec leans toward fixed installations like in an engine room.
Novec is good at quick response to the hint of a fire: a suppressant.
He believes it will not set off a propane sniffer alarm if it leaks: but believes it is safe.
Novec does not seem to do hand-held extinguishers (is this my error, John, because you report doing so?). For hand-held portable extinguishers there is a very similar stuff, FE 36. Novec is 3M while FE 36 is Dupont. Both are “clean” ie good for electronics and no clean up.
Extinguishers using FE 36 can be had from Ansul Clean Guard.
Neither are “A” approved (trash, wood, paper), just B, C (liquids, electrical) so to meet CG regs, other extinguishers may be necessary.
These are expensive products, but sound like they last a long time and are re-fillable.
My best, Dick Stevenson, s/v Alchemy