The Offshore Voyaging Reference Site

Crash Pump


The sound of gushing water from below has got to be right up there on any voyaging sailor’s list of worst nightmares. On Morgan’s Cloud, given that we believe that any pump that is practical for a yacht, no matter how powerful, is going to be of limited use in a flooding situation, we have always pursued a strategy of prevention, coupled with the gear and training to quickly stop a leak if one did occur.

But two of the comments to our recent bilge pump post got us rethinking:

  • Matthew pointed out that the pump we put such faith in is not thermally protected and will likely burn out in under an hour in an emergency situation.
  • Dick pointed out that large manual bilge pumps, like our huge Edson, are really pretty useless for a short handed crew because they are exhausting to operate and, worse still, using them will distract the crew from what should be the primary goal in a flooding situation: find and plug the leak.

Thanks to these two comments, and the others on the post, we came to the following three conclusions:

  • Our bilge pumps on Morgan’s Cloud were not adequate to at least slow the rising water while we looked for the cause of flooding, or to pump out the huge volume of water that might be left in the boat after we (hopefully) found and plugged a bad leak.
  • That we needed a pump that would run continuously for long periods and that would automatically cycle on and off using thermal protection if it did overheat.
  • There was no recreational electric bilge pump that was large and robust enough to do the job and had thermal protection.

So we went looking for an alternative in the commercial and industrial world and found a good solution.

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Dennis K. Biby

Interesting in the sense that a former girlfriend defaulted to engine starting in a crisis. Works great IF the engine starts but if it doesn’t the crisis becomes starting the engine – not sailing oneself away.

A hole four feet below the waterline spews a 1.73 psi geyser of water. See

Perhaps tis better to stuff a sock, plug, or … in the hole, a simple solution while others ignite the engine, rely on bilge pumps, or waste time trouble-shooting same.

Dos centavos,

s/v Ferrity

apt George Wall

Which is precisely why water detection should start with detecting traces of any water (or at a very low level before pumping begins) in an otherwise dry bilge. Waiting to start looking until when the “high water alarm” goes off or pumping starts, puts you behind the power curve in locating the source of the water.

Charles Starke

Great article!
How come you bought the 1/3 hp vs. the 1/2 hp?
It has larger diameter and flow output.
I am selling my large aluminum Edson on a board. Anybody want one?

Steve A

Hi John,
I have also been looking for a back up AC “crash” pump, and this one goes to the top of the list as I trust & respect your research & opinion. Can’t have too many pumps or redundancy. I wonder how long it could run dry before it burns up? Seems like the auto switch would be a good idea, rather than stationing someone to moniter water level at the pump.
My primary dewatering pump is a hydraulic Stanley SM21. It is made for use by utility companies to lower down manholes. Ok to run dry, pumps solids. According to the specs it pumps a staggering 5 gallons per second, 300 gallons per minute (1135 lpm) 18,000 gph, 50′ head max, 2 1/2″ hose. If you could direct the discharge stream it would probably propel the vessel! Weighs 20lbs, 6″x16″. Needs a 4-9 gpm hydraulic pump to power it, like a Vickers VTM42, which is a fairly small and common pump, though I installed something larger.
I agree that adding hydraulic pumps, compressors or alternators to the front of an engine is not the ideal solution. My dream engine or gear will accept a bolt on hydraulic pump…..however my Volvo has a bracket on the front to mount accessories on. My previous (commercial) vessel had an engine on flexible mounts and a hydraulic pump mounted to the hull. This was installed by the previous owner and as it was my first inboard I never gave it any thought. I discovered the misalignment while under full power and was shocked, it was obvious to the naked eye, but it was in the middle of a long summer season and there was no stopping to fix it. I carried a spare pump & clutch for a quick swap out, which was needed at 4,000 hours. The bearings on the $150 electric clutch were shot. I’m amazed that it didn’t eat belts (I kept them fairly loose) and the misalignment probably wasn’t doing the front end bearings any favors. I sold that boat with 9,000 hours on the engine and it is still going strong. I don’t advocate abusing machinery & would never install a pump like that myself….but feel pretty confident with a well aligned pump on a bracket that moves with the engine. That said I do carry several sets of belts, and a spare electric clutch.

richard s. (s/v lakota)

i still think it’s a good option to be able to switch the engine raw water intake from outboard to inboard including a well mounted and robust strainer for the inboard line…this could be just one of several remedies for flooding…probably can’t have too many…also means activating the valve switch from time to time probably using a sizable bucket to hold the water for the engine to pick up…just flipping the valve switch occasionally is obviously not enough to be really sure the option will work when and if really required although this is better than nothing when the bucket is occasionally just too inconvenient…cheers

richard in tampa bay

Svein Lamark

Hi John,
I think this is a good idea. I have had a pump like that for years and it works good. It is also an advantage that the pump is portable, you can move it around in the ship if necessary or also important: Help another ship that has a leek. Most yachts does not have a large portable pump, so if you inform The Coast Guard on the radio that you have that pump, you can be ordered to save another boat. This has happened to me and it ended good.
In Europe you can get cheap versions of this pump made of plastic, not polished stainless steel and they have a floating switch. The price is around 10% of yours. I have had one for many years and it is still working, but of course the quality is not the same as yours. On the other hand it is better than nothing.
Most marine diesels have a large pump built into the engine (in opposition to car engines converted to boat engines). This pump will always run as long as the engine runs to keep the engine room dry. Even if I have such a pump, I go for your solution because I feel safer that way.


Hi Svein, which pump could I get in Europe? I’m living in the Netherlands and preparing for an Atlantic trip next year. We’d like to buy a European version of the pump.


The pump looks good but I am not a big fan of the hose you have used. The advantages are that it is cheap and flexible. Unfortunately the corrugations cause a great deal of turbulence which reduces the flow. A smooth bore hose of the same diameter will allow more water to move from the same pump.

Dick Stevenson

Dear John,
I agree with Stan if your hose is as rough on the inside as it looks to be. Edson makes a hose (which I kept when I sold my big portable Edson pump) which is flexible as it has those ridges on the outside but is smoothed out on the inside. This hose, I believe, was designed to move large quantities of water with less interference.
My best, Dick Stevenson, s/v Alchemy

Dick Stevenson

Dear John,
I have some concerns about the amount of time you would need to get your pump up and running. Have you timed it?
I had a similar set-up that should have been a little easier to get going than I suspect yours could be in that my pump was permanently installed. I needed to get out the discharge hose, attach it (Edson quick connects), run it outside the cabin and tie it off so it did not flail about when full of pressurized water. I could not get the pump up & running in less than 2 minutes. I considered that 2 minutes, done under optimal conditions, too long for me to not be searching for the leak in a flooding situation. Every inch the water level rises makes finding the leak that much more difficult and unlikely.
I think your pump choice is marvelous as well as the thinking about powering it. I would, however, suggest considering making the pump permanent, ready to go at the flick of a power switch. If you want a portable pump, then repeat what you now have. Your boat is big and you have the room.
BTW, I consider $400 not out of line for what you describe. There are 2 scenarios that feel very scary to me on a boat: flooding & fire. And being prepared to deal with them is money well spent as it allows me to sleep better.
My best, Dick Stevenson, s/v Alchemy

Petter ;-)

Nice article John,
On-board Iris the “bread and butter” solution is an electric Rheinstrom M50 diaphragm pump which also comes in a manual version. ( The electric version is said to be a rugged, solid work horse of a pump. If one couples this with a manual version of the same, a fair amount of spares is interchangeable. The electric pump is manifolded to suck from various selectable compartments.

As a crash pump, I have chosen a solution similar to the one on Morgans Cloud, with a few modifications. As Svein Landmark pointed out, the 220V pumps also exist in a rugged plastic version a very attractive price, so we have opted for that. It can be driven either from a Mastervolt inverter or a separate portable petrol honda 2kW generator. I agree with you John that petrol is not ideal and fiddling with a starting it may not be a prime concern. However, as the portable generator will have work on deck, if it start, is will continue providing electricity to the pump even if ship is fully flooded (hopefully not), and in a situation when both batteries and the main engine is not functioning any longer. This may provide valuable float-time in a case where an evacuation is the only solution.
It is being said that the right time to leave the vessel, is only when you have to step up to get into the life raft.

Petter ;-)

I forgot to mention the item that inspired me to comment in the first place. To save space on-board the above pump has been fitted with a collapsible fire hose. Hopefully it opens up and stays open with the 15.000 liters/hour gushing trough the hose.


I bought a collapsable fire hose and returned it because the pump could not keep the hose open. Seemed like an ideal solution but did not work. Also having a hard time finding an adapter that goes from 1 1/4 ” thread to 1 1/2″ hose barb. Still looking.


The Rheinstrom pumps are great. I use one to pump my dirty water tank. Bread and Butter…Hmmm… mine cost around 500 Euros. Do not use the bilge pump model in an engine bilge. the valves cannot handle oil. The dirty water M50E model seems to handle a little oily water ok though.

Matt Marsh

Re. standard bilge pumps:
Their ratings are usually based on perfect conditions (no discharge hose, engine running, batteries fully charged, no voltage drop in the wiring). I find that if I assume they’ll pump half their stated capacity – at best – in an actual installation, I’m probably not too far off. More here,

Commercial pumps like the one John’s talking about tend to have fairly realistic ratings. The good ones also have published performance curves (like this: ) that tell you how the rating will change with additional head or reduced revs.

Bob Hinden


Interesting post. I found a somewhat similar DC pump. It says it has a 1/3 HP motor that delivers 2580 GPH (43 GPM). Meant to connect to a car batter, but could easily be adapted to run from the house bank. This would avoid all of the AC issues you describe.


What do you think?


Charles Starke

I found a Gould’s LSP07 stainless pump at Depko pumps for $257, that is much cheaper, 3/4 hp, heavier duty and comparable to the pump above. The 3/8 hp LSP 03 sounds very similar.
“• Single phase, 3450 RPM, 60 Hz
• LSP03, 1⁄3 HP, 115 V, 2.9 maximum amps
• LSP07, ¾ HP, 115 V (7.1 amps) or 230 V (3.5 amps)
• Built-in thermal overload protection with automatic
• Permanent-split-capacitor type
• Class B insulation
• Stainless steel shaft
• Air filled design
• Power cord length: LSP03; 10 feet standard, 20 feet
optional, LSP07; 20 feet ”
Capacity 57 GPM at 10 feet!!!
Does anyone have any opinion? It sounds like a better buy.
I have a 2500 watt inverter, generator or engine that could run this.
Where can I get flat fire hose in US?
Best wishes,

Petter ;-)
Charles Starke

Does anyone have thoughts on the comparison between the Goulds and the one recommended? I was going to buy the Goulds if there are no thoughts of major problems with this one.
I will get the fire hose, and post how this works out.


If there ever was a reason to have AC on a boat, this is it. AC industrial pumps are so impressive, the abuse they can take, some can pump very thick sludge. The guys on the building sites don’t exactly treat them with kid cloves.
Of course the good ones are not cheap.
I guess the reason that the leisure boating world does not have a real bilge pump, is that no-one demands it. I am fairly sure that over 50% of the installed leisure bilge pumps don’t work well in general and maybe 95% won’t actually save your boat when called on.
I wonder how the guys on a building site would react if someone gave them the very best leisure bilge pump on the market today to pump out a flooded building site on Monday morning.

Philip Waterman

A rant about “non-user serviceable” internal fuses.

I have noticed a trend for the manufactures of electronics and electrical systems to design in internal fuses that are designated as “non-user serviceable”.

Recently, we had to bin (or rather sell on Ebay for spares) a six-year-old Canon Camera, which in its day was the top of the range, because a surface mounted fuse on the main circuit board had blown.

Of course Canon’s service people would have happily replaced the PCB at a cost very close to that of a new camera with a similar specification – thanks to Gordon Moore.

I am not saying it would have been easy to replace a surface mounted nano-fuse, however, if Canon had been able (or permitted) to tell me where it was and identify the component, I would most certainly have had a crack at it to avoid trashing the Camera.

I have a degree of sympathy with consumer electronics manufactures. Such fuses are almost certainly mandated by the product liability insurers for markets where no one would consider switching on a system without their lawyer standing by with a video camera. I am sure that Canon had a good reason to consider a scenario where the internal lithium memory battery, through some hitherto unknown chemical reaction, produces one hundred times its voltage and sets alight a great public building.

However………when a leading Dutch manufacture of marine electrical systems has a policy “not to give details of, nor supply spares for internal components”, including PCB mounted fuses, I get annoyed.

Of course there is a repair or swap out service facility – unnecessary and expensive for a blown fuse and not so easy mid-Atlantic.

I currently have a very expensive turquoise and grey box, whose PCB mounted fuse has been destroyed (literally) by a voltage spike in a marina. Sadly, it is so badly damaged, that it is impossible to identify the component.

In the absence of information from the manufacturer, I could make an educated guess at what this rather particular axial leaded fuse is. Of course, if I get it wrong and a subsequent fault sets alight a great public building, it will be my fault for not following the manufactures repair policy and most certainly not their fault for refusing to give me the specification of the fuse.

Here endeth the rant – thanks I feel better.

Bill Shuman

This is all very interesting but one thing keeps nagging me… these pumps will keep up with a 1″ hole in the boat up to 4 feet below the waterline or 1-1/2″ hole one foot below but anything bigger than that and they will be overwhelmed. Does anyone know what is typical for a water ingress emergency? In what percentage of real life scenarios would this pump make any difference? Thanks.


I bought a Gould’s LSP07 stainless pump at Depko pumps for $257, along with two inch flat fire hose on Amazon. The hose rolls up and stores well on the pump. Pump is 3/4 horsepower and starts easily on the 2500 watt inverter. I also installed a 110 plug directly off the generator since it is so high and would be the last to flood.
This works well and I recommend this setup.
I agree with previous comments that the first order of business is stopping the leak but we sail with at least two crew and one can search for the leak and one can get the pump running. I previously carried a big Edson, but don’t see how to man this easily and also find the leak.

Philippe Sandelé

would like your comments on the following possibility for a non-electric, high capacity bilge pump

In case of a saildrive engine, one could consider installing a short separate shaft connected to the engine with a belt to drive the shaft/pump.

Charles Starke

Happy Thanksgiving, John and Phyllis!
I bought a Fast Flow pump but had to return it since it was impossible to fit in my boat’s bilge. Their service was friendly and they took the return with no problems. Construction looked excellent.
But it looks great, and if you can fit it, it seems a superb solution. There is no load on the engine if there is no water in the bilge. It works automatically if there is a leak. And WOW!, you are going to see it work right away with a leak and the engine running.
I bought the Goulds pump (described above) instead, and fitted a dedicated 110 plug in the engine room running off the generator. It’s portable and, for fun, I emptied a 20′ boat sitting at the dock and filled with rain water, in under 20 seconds.

Alan S

Another DC alternative is a Rule Evacuator Pump
created by putting 2x 4000gph pumps into a common casing. Obviously will have the same operational limitations that their bilge pumps have.
It would probably have a similar realistic output to John’s AC pump. The outlet is 3″ which needs a big hose – I have a lay flat hose altho this is not preferred.
Sea Tow boats carry these as a pump to pass over to vessels taking wáter.
One comment on the Ericsson Safety pump – looks a good concept but in my view is flawed because the drive shaft has to be turning to pump, in an offshore flooding situation ie no beach to drive up, the last thing you want is to be moving the boat as this could just accelerate the inflow



I like your idea of using 110v commercial pump. Currently I have 2 Rule High Capacity 12v pump with a Y connector to a single thru hull – not a good idea. I discovered during a test that there was a leak at the Y joint so no water was going out of the boat.

I dread if my boat were to flood as I have the main and genset below floor board making any 240v high capacity pump useless. Will have to work on a better high water sensing and alarm.

Thanks for the great idea.


apt George Wall

In following the article link to McMaster Carr site, the pump motor is described as “intermittent duty”. Is this link correct?


apt George Wall

Thank you. I usually get the manufacturers technical spec sheet on any item like this. In order to do that, I need the manufacturer and model which is not available on McMaster-Carr website. Can you help?


Eric Klem

Hi George,

McMaster is really helpful both by phone and email. I call them on a fairly regular basis for work and they will happily provide the original manufacturer and model number as well as a spec sheet.


George Wall

I’ve converted to the crash pump. Any suggestions on how to wire it for unattended operation with rising water in the bilge? 12 volt bilge pumps are easy by comparison.

capt George Wall

I’ve just completed my wiring. Here’s what I did:
1) installation is permanent in Bilge.
2)Wired a float switch and a toggle switch (to manually turn pump on and override float switch) to a GFI outlet
3) added 12v bilge pump switch wired only to Loud Buzzer(wake the dead loud).This acts as earl warning signal that there is about 5″ of water in bilge(which is usually dry) and allows early investigation of problem and manual operation of pump.
4)I also have a cell phone connected alarm system that detects water levels above the Buzzer level that calls my cell phone if water reaches that point. Which should give enough early warning to get to boat at Marina to investigate problem.

capt George


This discussion is interesting. However the AC running with a boat bouncing in the water, maybe heeled on the wrong side… maybe having a couple 100s gallon of salt water slushing inside… is the last thing i would want. One emergency is enough than having someone electrocuted. I have a small Honda pump vacuum wrapped ready to go. It will run inside the boat tied to a seat. I have a steel hull with crash protection in the front and the first bulkhead is watertight. So if water get’s through, and the three 4000 liters/hour can’t work it so i can solve the problem, then its a real first class emergency and i figure the 45 minutes of fuel i have should be enough – otherwise we should take the raft. I also have the intake of the engine on its impeller side connected to a Y valve so i can choose to evacuate water if need. But its only a sailboat, if i had more space i would have installed an engine driven damage control pump on it.


Hi John

Thanks for your precision. I agree with you – nothing is perfect ! It is possible to get a “safe” AC on a dry boat, this is what the ABYC rules give guidance for. But if the assumption is that there is sea water entering the boat, then the design of an AC damage pump should start with the placement of the inverter first. i would also make sure the pump is on a dedicated AC circuit not shared by any other AC appliances or socket. It suffice of one cup of seawater at the wrong place and the breaker will trip and the pump will be useless. I’ve seen in your post that the current AC setup on your boat is compliant with those requirements but just wanted to emphasis this to anyone contemplating installing such a pump.

The sad thing is that we all have 50 HP to spare and most diesel engines can continue working (mine has a mechanic pump) until they suck water which in my case should be when i’ll be on the raft, but to try to harness that power for a damage control pump is much difficult 🙁

Jim R

Hello John,
Some transmissions have bolt on PTO’s that can be used to power hydraulic windlasses / bow thrusters. That would seem to be a good source to power a hydraulic crash pump if already fitted. Granted, the con of having to start the engine remains. Thoughts?


I have completed the physical installation of the recommended 115v crash pump. I would like to control it with a traditional bilge pump switch and control circuit (this would help prevent continuous running as every time the bilge emptied the pump would stop)
Any suggestions?

AJ Kinney

John, thanks for all the great information about bilge pumps and switches. Can you give me the diameter of the 1/3 hp pump? It is not listed on the McMaster-Carr site, and I have limited access to the deep bilge because the drive shaft, V-drive, and prop shaft are directly over it.

Marc Dacey

Did you check under “sump pumps”? There’s a wide range of options (with dimensionals) here:

AJ Kinney

Oops – temporary blindness, I guess. I now see it is 6″ diameter. I think that will fit, but I’ll need to measure.


I bought the High Flow bilge pump you recommended, but my 1500 watt Xantrex inverter is not powerful enough to run the pump. It cycles on and off continually when connected to the inverter because it cannot handle the startup load. However, the pump runs well when connected to shore power. Can you please tell me what stats I need in an inverter to adequately run the pump? I’d also like to know what brand and model inverter you have?
Something else to know is that I bought a collapsible fire hose with quick connects from CTW, which does not work because of the tendency to kink.
To make sure the pump was working correctly, I tested the pump by plugging it into AC and tossing it into my backyard pond. The pump runs well when connected to regular
1 1/2 inch hose. With no hose, It can empty a 5 gallon bucket in 4 seconds.



Eric Klem

Hi Larry,

Is the pump marked with manufacturer and/or part number?

If not, you might try asking McMaster what the startup load is. They are usually really good about getting more specs for you if you ask. I order from them all the time for work and occasionally need more info on a part which they can usually provide. When they have gotten stumped they have referred me to the actual manufacturer who can answer.



Would this inverter be sufficient to run the pump?
Xantrex PROwatt SW 2000, Pure Sine Wave Inverter

I saw it advertised for $415.00 here: