Bilge pump questions

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kazenza

kazenza

Veteran Member
Joined
May 20, 2013
Messages
31
Location
USA
Vessel Name
Sea Rover
Vessel Make
CT 40 / Hartley Motor Sailor
Any strong preferences on automatic bilge pumps vs a pump w a separate float switch. Also, has anyone any experience with the aqualarm heavy duty bilge switches. Are they more reliable than the rule float switches.

Randy
 
Just a newbies opinion, in my experience some of the rule pumps with the built in float failed due to oil in the bilge water (some of there documents even warns of this), while a bit more costly I have installed dozens of "Senior Ultra Bilge Pump Switchs" both commercial and pleasure boats without ever having a failure, and the neat feature is that it controls the pump as well as high water alarm. As far as the pump IMHO the mayfair magnum pump is a great pump, again I have installed many of these in no CG inspected vessels as it only has the ISO and CE standard as of yet so I cant install on commercial in that case I go to the smaller mayfair pumps. Hope this helps and again this is only my opinion as a newbie.
 
My concern with the automatic bilge pumps would be the noise of the thing starting regularly to check for water. I'm not sure I'd want to hear that when sleeping.
I have used Ultra Safety System pump switches on boats for something like 20 years now and although the design is good and sold as perfect we've experienced a couple of failures.
The company refused to acknowledge the "lifetime" warranty and suggested that the only way a switch could fail was a lightening strike or a perhaps if the switch was left under standing water...
Well, it had been under water as it stopped turning the pump on and off...

Anyway, they are good switches but don't expect factory support if anything goes wrong.
Bruce
 
I have used Ultra Pumpswitches for years and found them to be very reliable. Several reports and one personal experience lead me to believe that the guy who makes them may be slightly "out of alignment".
 
Shoalwaters said:
I have used Ultra Pumpswitches for years and found them to be very reliable. Several reports and one personal experience lead me to believe that the guy who makes them may be slightly "out of alignment".
Click to expand...

Your assessment of the owner is very kind...
Bruce
 
Regarding automatic versus manual, IMO it depends on whether you regularly get water in the bilge. My trawler bilges (2 compartments) are essentially dry (none of the pumps have cycled in 6 months). Makes no sense to have a pump that checks for water if there usually isn't any. My charter boat has hatches that leak when it rains, when I wash the boat after a charter, and when scuba divers come back on board. This boat also has a long narrow keel that the remaining water sloshed back and forth in. This was hell on the pumps and float switches with a lot of short cycling. The automatic pump works better in this application.

Can't say as I'm overly impressed with the quality of the automatic pumps.

Ted
 
What is the size of the thru hull opening? This un-looked detail often makes people select the wrong bilge pump thereby shortening pump life. The typical hose sizes will be 3/4" or 1-1/8". The pump should match that hose size without using any reducers. Having any check valve in the line also adds head pressure along with hose type, length, and actual lift. All of those things need to be considered when selecting a bilge pump size. Nearly everyone picks a larger pump which only ends up shortening the life of the pump without pumping any additional water out.

And with check valves, having any in a bilge pump system is a mistake of the design (ANY). There is always a way to get around using a check valve while providing a better solution of removing the water. Check valves in a bilge system can easily sink a boat but mostly shorten the life of the pumps.

It's shocking how little information about all of this is out there. The pump manufacturers are motivated to make us think we need bigger pumps and that "they all fail so keep some backups." What most boats need are smaller pumps that are put in properly.
 
Shoalwaters said:
I have used Ultra Pumpswitches for years and found them to be very reliable. Several reports and one personal experience lead me to believe that the guy who makes them may be slightly "out of alignment".
Click to expand...

Those are pretty much the only switches I use. I think I've only seen one or two fail in decades.

Can't speak to the mental health of the company owner. Never had to deal with him.
 
Jeffrey S said:
It's shocking how little information about all of this is out there. The pump manufacturers are motivated to make us think we need bigger pumps and that "they all fail so keep some backups." What most boats need are smaller pumps that are put in properly.
Click to expand...

Could not disagree more!

Boats need smaller bilge pumps!? That's a first.

Most boats have to few and to small a capacity pumps from the get go. And while it's worth check into, I rarely see pumps installed with the wrong size thru hull.
 
Capt.Bill11 said:
Most boats have to few and to small a capacity pumps from the get go. And while it's worth check into, I rarely see pumps installed with the wrong size thru hull.
Click to expand...

I think I've written 3 articles about it so far with another 3-5 still coming. The first one was about hose size/thru hull size comparing it to pump outflow size. I'd bet we received 400 emails from people who went and measured to find that their pumps were the wrong size for the hose and thru hull. Four of the bilge pumps on Red Head had the wrong size thru hull/hoses. It is very, very common - all you need to do is look at the pump itself and see if there's a reducer right at the pump - that's where most people put them going from 1-1/8" to 3/4" for a typical Rule 1500 or 2000. It's just simple physics that adding a bigger pump will not put out the amount of water expected if the outflow pipe is smaller than specified. Rule themselves include the reducer so people can use the pump. But it's a pump-life mistake to put it inline. And again, because it can't be said enough, check valves are even a worse mistake.

I was at a yard for 4 months this summer with Red Head. The guys there are all career boat builders with tons of experience. They all know that these larger Rule pumps give shortened life because the hose connection is too small. They'll re-install a thru hull and use the same exact type of pump and it lasts for many years. Centrifugal pumps shouldn't "burn" out but everyone agreed that they do - could be cheaper parts used or something that doesn't like the added head pressure.

It's a pretty good exercise - go measure your own hoses and thru hulls. I'll bet that most are 3/4". If you're using a Rule 1500 or 2000 (or larger), your bilge design isn't really right - it has a 1-1/8" output. If it's in an area that is pumping occasionally, you're likely seeing reduced pump life. If it's for an emergency and is never really pumping, life won't be reduced but it also won't pump the water you're expecting by a long shot. It would be much better to have a second smaller pump installed to a different thru hull and reduce the pump size of the original one next time it fails.
 
I would NOT get a so-called automatic pump. Every one I have ever had failed in short order. I would also never buy a Rule pump, Since ITT bought them a number of years ago the quality has been terrible. I have had way too many Rule pumps fail as well. I think I'd give Johnson Pumps a try next.


And I don't think Jeff is saying you want less pumping capacity. He's just saying that if the pump size isn't matched to the hose size, you will reduce the pumping capacity and shorten the pump life. So if you want more pump capacity, you will likely need to increase hose and thruhull sizes.
 
In my opinion both Jeff and Capt Bill are correct.

If you are going to install pumps...make sure you are doing it right so the advertised gph is close to what you are getting.

Going smaller isn't really what anyone really recommends...just go with what you might expect from a through hull breach or other common taking on water emergency.

As I have said repeatedly...if you hit something and crack or breach the hull...the chances the average boats bilge pumping capacity will be 1/10 of what is required would be a miracle.....better know damage control and the steps to go through.
 
Last edited:
psneeld said:
Going smaller isn't really what anyone really recommends...just go with what you might expect from a through hull breach or other common taking on water emergency.
Click to expand...

It's the entire system that matters. The pump is just one part. Pulling out a pump that's installed and installing a pump with 4 times the pumping capacity will generally not provide any more water outflow. Experience suggests it will only destroy the pump.

Wire size has a significant impact as well. Sure, you might install a large pump but do the wires and voltage drop support the pumping you think you'll get? Usually not. I've yet to find someone who actually measured the voltage drop of their bilge pump power feed.

If anything, the pump is the simplest part of the system and the least capable of modifying to something that matters. Thru hull, hose, and wiring often cast the die of the result much more than the pump. And yes, in most systems I've come across, the pump was too big - a smaller one should have been used instead with additional design to remove the water that might need to be removed.
 
Jeffrey S said:
It's a pretty good exercise - go measure your own hoses and thru hulls. I'll bet that most are 3/4". If you're using a Rule 1500 or 2000 (or larger), your bilge design isn't really right - it has a 1-1/8" output. If it's in an area that is pumping occasionally, you're likely seeing reduced pump life. If it's for an emergency and is never really pumping, life won't be reduced but it also won't pump the water you're expecting by a long shot. It would be much better to have a second smaller pump installed to a different thru hull and reduce the pump size of the original one next time it fails.
Click to expand...

How much do you want to bet?

Before you answer I think it's only fair to tell you I have 5 Rule 3700s plus a 1&1/2" discharge diaphragm pump on a manifold that I can direct via valves to low spots at each of 5 bilge areas.

So the likelihood of me having any 3/4" sized discharge thru hulls or bilge pump hoses is pretty much zero.

But I'm willing to take your bet if you're still game. :D

As I said, I haven't see a lot of reduced bilge pump hoses/discharges. But perhaps that has become in a an issue with newer boats.

And I sure as hell haven't met anybody who thinks having smaller bilge pumps (other than perhaps one or two to get the last drops of water out of the low spots in the bilge) is a good thing.

But as they say, YMMV. So I guess get back with me sometime after you start sinking and let me know how that smaller pumps are better theory worked out for you. :D
 
The rule float switches have a reliability problem in my opinion they quit in the on position and if you do not hear it it will burn up the pump. in fact I am done with most products from jabsco. as I feel the quality on most of the products is poor
 
Jeffery,

Can you explain the check valve failure that could cause a boat to sink? I am thinking of installing a check valve since on the rare occasions I end up with water in one bilge after draining the hot water tank, every time the pump runs and then shuts off, the back flow from the anti-siphon loop triggers the float switch again.

Tom
 
I have looked at this a few times. I am not happy with my bilge pumps and am looking to add additional pumps and thru-hulls.
My thru-hull is 2 1/2" from a collection box. The bilge pump is a Rule 3700 with Ultra Switch. I have a smaller Rule 500 pump to clean up any smaller amounts of water night next to the 3700.
 
motion30 said:
The rule float switches have a reliability problem in my opinion they quit in the on position and if you do not hear it it will burn up the pump. in fact I am done with most products from jabsco. as I feel the quality on most of the products is poor
Click to expand...

ITT bought Rule a number of years ago, and more recently bought Jabsco. Then ITT spun out the pumps group creating Xylem. Same crap, different name.
 
tpbrady said:
Can you explain the check valve failure that could cause a boat to sink?
Click to expand...

I don't agree with everything ABYC says but they're quick to not allow check valves in bilge systems. They specifically and strongly warn against them as backflow devices for bilge discharge systems in any type of attempt at stopping a siphon flow back into the boat - they are often used for that when a proper siphon break/loop isn't possible because of space. But they are dangerous in that use.

Check valves used in non-clean water environments like bilges fall easy prey to having debris caught in the check valve causing them to fail. As time goes on, they often require more pressure to open too which greatly overloads the pump creating another reason for short life and failure. So failure to close can sink the boat through water siphoning back. Failure to open will stop the water from pumping out which could also sink the boat (although not in your case as a hot water drain).

Given the small amount of water when occasionally draining your water heater, you should look into a diaphragm pump - the Whale Gulper is a good example. You can mount the pump remotely and get nearly all the water out of the bilge when needed using a pump like that. It's a much better way to go. The typical centrifugal pump isn't really made for the function you're trying to put it into.
 
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HenryD said:
I have looked at this a few times. I am not happy with my bilge pumps and am looking to add additional pumps and thru-hulls.
My thru-hull is 2 1/2" from a collection box. The bilge pump is a Rule 3700 with Ultra Switch. I have a smaller Rule 500 pump to clean up any smaller amounts of water night next to the 3700.
Click to expand...

A 2-1/2" thru hull for bilge outflow is super large. That's usually a size of engine outflow!

You have a pretty good design although you too would find that you'd like your system much better if you replaced the Rule 500 with a Whale Gulper. The 3700 should also be mounted higher than the Gulper. Let it grab the bulk of water in emergency situations and have the diaphragm pump handle the rest of the water - it's made for that.

Many people are unhappy with their bilge pumps because what they really want is a "drying" pump and not a bilge pump. There should be bilge pumps to remove large amounts of water especially in emergencies - they are often handled with centrifugal pumps like the Rule's. Drying pumps are meant to get the last bit of water out. Something like a Whale Gulper is perfect for that. They are made to pump dirty water and won't clog either. That's another reason to mount the bilge pump above the drying pump - let it handle the cleaner water since centrifugal pumps can get fouled with dirty water.

The next issue is that when there are two pumps in proximity, there is often the desire to throw in two check valves so both can outflow through one thru hull. Avoid that desire - have a second thru hull or other collection mechanism to allow the system to work without check valves. Never, ever have a check valve in a bilge system.
 
Jeffrey S said:
I couldn't care less. If your boat has a well-designed bilge pump, good for you. If you don't want to share the details, why respond?
Click to expand...


"I couldn't care less."

Then why respond?

And I take it the bet is off? :rofl:

As to the details, I thought those were pretty clear. 5 - 3700s and a 1 1/2" diaphragm pump on a valved manifold.

But if you want more details, the 5 3700s have Ultra switches with high water alarms on them, proper sized hose, proper sized thru hulls and unfortunately check valves. I use very simple check valves that so far have given me no real issues. But I'm sure they restrict the flow some.

The diaphragm pump is a 24v Sealand pump that I installed to replace the factory installed manual pump using the existing manifold. I just had to remove the original check valves and replace the old clogged up foot strainers. The hoses and they hull for this system are properly sized as well.

Then we have 3 sumps with 2000 gph pumps in them, all with proper size hose and fittings, for things like showers, sinks, A/C drains etc.

And we have a couple of shop vacs onboard.

Oh, and several 5 gallon buckets. Do you think I should down size those as well as my pumps? :popcorn:
 
Randy, concerning your question about the Aqualarm bilge switch, I haven't sold enough to get a feeling about their reliability but it appears to use a similar system to the Ultra Safety System floats. It's probably pretty good.
 
Thanks to everyone for the discussion. Another reason I love this forum. Just FYI I am refitting an 81 CT 40 trawler that was bought, pretty stripped out, on Lien sale by the previous owner. Having to replace nearly everything except the engines. The boat has a continuous bilge. Right now I'm replacing all the electrical including panels,gauges, and alarms. I saw the aqualarm switches which prompted my question ab bilge systems.
 
Jeffrey S said:
I think I've written 3 articles about it so far with another 3-5 still coming. The first one was about hose size/thru hull size comparing it to pump outflow size. I'd bet we received 400 emails from people who went and measured to find that their pumps were the wrong size for the hose and thru hull. Four of the bilge pumps on Red Head had the wrong size thru hull/hoses. It is very, very common - all you need to do is look at the pump itself and see if there's a reducer right at the pump - that's where most people put them going from 1-1/8" to 3/4" for a typical Rule 1500 or 2000. It's just simple physics that adding a bigger pump will not put out the amount of water expected if the outflow pipe is smaller than specified. Rule themselves include the reducer so people can use the pump. But it's a pump-life mistake to put it inline. And again, because it can't be said enough, check valves are even a worse mistake.

I was at a yard for 4 months this summer with Red Head. The guys there are all career boat builders with tons of experience. They all know that these larger Rule pumps give shortened life because the hose connection is too small. They'll re-install a thru hull and use the same exact type of pump and it lasts for many years. Centrifugal pumps shouldn't "burn" out but everyone agreed that they do - could be cheaper parts used or something that doesn't like the added head pressure.

It's a pretty good exercise - go measure your own hoses and thru hulls. I'll bet that most are 3/4". If you're using a Rule 1500 or 2000 (or larger), your bilge design isn't really right - it has a 1-1/8" output. If it's in an area that is pumping occasionally, you're likely seeing reduced pump life. If it's for an emergency and is never really pumping, life won't be reduced but it also won't pump the water you're expecting by a long shot. It would be much better to have a second smaller pump installed to a different thru hull and reduce the pump size of the original one next time it fails.
Click to expand...

Jeff, I completely disagree with your conclusion that restrictions in a centrifugal bilge pump discharge hose will somehow shorten pump life. The fact is with a centrifugal pump, restricting the discharge flow via system flow resistance ( hose too small, too long, clogged HX, throttled valves, etc. ) reduces power and therefore amps used by the motor. It makes no difference if the motor is DC, AC, steam, or hydraulics. The power requirement goes DOWN with reduced flow.
This is easy to prove with a garden hose and installed typical Rule bilge pump, clamp on DC ammeter and seacock. Fill a bilge compartment with garden hose until the float switch activates and read the pump amps after the initial start amps clear. While reading the ammeter, throttle the outlet seacock 3/4 of the way closed. Amps and power consumed will go down, not up. Thats not what is causing your pumps to fail.
Positive displacement pumps like a diaphragm pump work the opposite. Same test with an old style diaphragm pump. If you throttle the seacock closed, the amps will go up until the motor stalls, a relief valve opens, or something fails.
I spent 33 years running fully instrumented centrifugal pumps in 3 different nuclear power plants. The theory is the same whether it is a 600 GPH bilge pump or a 22,000 GPM Reactor Recirc Pump or a 13,000 GPM steam driven feed pump.
 
High Wire said:
Jeff, I completely disagree with your conclusion that restrictions in a centrifugal bilge pump discharge hose will somehow shorten pump life.
Click to expand...

I know. When we release a newsletter, it goes to about 250,000 boaters. Scores of them replied to say the same thing. I understand the physics about centrifugal pumps. And in a purely theoretical way, it shouldn't shorten life. I agree with you.

Now contrast that to a yard full of mechanics and boat builders from 4 yards. My daily contacts were with guys having 25-45 years of experience helping me understand why 20% of the bilge pumps on Red Head had failed. They made it clear. A lifelong customer comes in with a burned out pump. They replace the pump and in a couple of years it comes back, burned out again. Eventually they instead remove the 3/4" reducer and put in 1-1/8" hose along with a 1-1/8" thru hull. The pump never comes back for replacement. Similar things happen if they reduce the size of the pump to something spec'd for 3/4" outflow.

They told me how it's a very consistent finding. So you can argue the physics of centrifugal pumps all day long. In the end, the pump burns out.

Yogi Bera explained it best:
"In theory, there is no difference between practice and theory. In practice, there is."
 
tpbrady said:
Jeffery,

Can you explain the check valve failure that could cause a boat to sink? I am thinking of installing a check valve since on the rare occasions I end up with water in one bilge after draining the hot water tank, every time the pump runs and then shuts off, the back flow from the anti-siphon loop triggers the float switch again.

Tom
Click to expand...

Jeffrey explained it well. My primary concern in your application would be if the valve failed over time. This wouldn't be a siphon issue in the NT42 if I recall, but a failed check valve can fail to open fully as well as fail to seal closed. This could create problems with the pump not being able to open the valve when it comes on.

The the last bit of water, you could always look at something like the dry bilge system. I actually have one that I have yet to get around to installing. Of course by the time I have the time, being the mess that my life is, I likely won't be able to find it. :banghead:
 
Jeffrey S said:
I know. When we release a newsletter, it goes to about 250,000 boaters. Scores of them replied to say the same thing. I understand the physics about centrifugal pumps. And in a purely theoretical way, it shouldn't shorten life. I agree with you.

Now contrast that to a yard full of mechanics and boat builders from 4 yards. My daily contacts were with guys having 25-45 years of experience helping me understand why 20% of the bilge pumps on Red Head had failed. They made it clear. A lifelong customer comes in with a burned out pump. They replace the pump and in a couple of years it comes back, burned out again. Eventually they instead remove the 3/4" reducer and put in 1-1/8" hose along with a 1-1/8" thru hull. The pump never comes back for replacement. Similar things happen if they reduce the size of the pump to something spec'd for 3/4" outflow.

They told me how it's a very consistent finding. So you can argue the physics of centrifugal pumps all day long. In the end, the pump burns out.

Yogi Bera explained it best:
"In theory, there is no difference between practice and theory. In practice, there is."
Click to expand...

If you are using generic yard workers and boat builders...that's a scary bunch.:eek:

Heck with my experience, a few here think that all my years of experience doesn't count for anything...so why would you think theirs amounts to anything? :D

Guys like CMS try to do a great job of taking their real life experience and doing some anylitical research into all these dofferent boating questions. :thumb:

Like Steve and the anchoring videos too. :thumb:

I agree that many electric bilge pumps are installed poorly. I am not sure that many are installed with downsized hoses and through hulls...but improper hose, length of hose, bends, check valves, poor wiring, etc are all factor I agree are bad.
 
Last edited:
Well being just a "generic yard worker" I tend to agree with the fact a restricted pump will fail sooner. Not being an engineer or possessing a physics degree I dont understand some things but I know what I see. If a customer brings me or I obtain a larger pump he gets a larger hose and thru hull and is happy. As for check valves, being from the northeast where most boats are put up for the winter, and due to poor owner maintenance or winterizing I find a lot of damaged valves, hoses and housings damaged. These issues could be existing on many boats without the owner even knowing, possibly untill to late.
Just my 2 cents worth
 
SBR said:
Well being just a "generic yard worker" I tend to agree with the fact a restricted pump will fail sooner. Not being an engineer or possessing a physics degree I dont understand some things but I know what I see. If a customer brings me or I obtain a larger pump he gets a larger hose and thru hull and is happy. As for check valves, being from the northeast where most boats are put up for the winter, and due to poor owner maintenance or winterizing I find a lot of damaged valves, hoses and housings damaged. These issues could be existing on many boats without the owner even knowing, possibly untill to late.
Just my 2 cents worth
Click to expand...

Nothing petsonal...unless you fit the description.

One could accuse me of being one too if they didn't know me.

But all I was alluding to was that I haven't seen too many installs where someone added a significantly larger bilge pump but reduced it down to whatever was there before.

99 percent of bilge pump replacements I have seen or been involved with are either direct replacements for output and hose diameter...or there is an increase in hose size and thru hull size.
 
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