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Old 01-17-2017, 04:49 AM   #41
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I have no doubt PSNEELD knows what a reducer looks like. I also suspect that there are many incorrectly installed bilge pumps out there. Here is a recent example:
My own 21' Sailfish CC came from a well respected major dealership/boatyard. The PO who bought the boat new wanted the extra security of a second bilge pump which the dealership installed. He never mentioned the second pump to me. Both pumps and float switches were located at the transom, under a platform that held 2 batteries, a battery charger, a saltwater washdown pump, and a freshwater washdown pump. Access to the pumps required serious disassembly. The PO only trailered the boat for day use so it was normal to pull the boat and drain plug every trip at the ramp. When I bought the boat, my plan is to leave the boat in a marina slip from April to November. The first time I washed the boat down in the slip (all 11 cupholders and rodholders drain into the bilge), I hear the bilge pump come on and with it a loud sloshing noise from below. The outlet is spitting water occasional then whoosh, the outlet shoots out a stream several feet out the side then shuts off. WTF was that all about? Curiosity stops my boat wash. Time for a functional test which I admit should have been done prior to launch. Fill the bilge from the hose and lets see whats going on. Same thing. Well something must have come loose and since I'm in the slip it needs to be fixed right now. What I found, surprise, was the second pump. The second pump discharge was TEE'd to the first pump with only one outlet. Whichever pump started first pumped its water out the suction strainer of the other pump, aggitated the water enough to trigger the second float switch, then both pumps together would empty the bilge!!! Even better is the installer TEE'd the second pumps power off the first pump downstream of the fuse so BOTH pumps were powered by the same 15 amp fuse.
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Old 01-17-2017, 07:15 AM   #42
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I am going to weigh in on this.

Having seen only the bilge pumps on our own boats, those owned by friends on the dock and boats I have helped fix while cruising I have my own thoughts.

First, most bilges are beyond disgusting! The average bilge would make a billy goat puke. They are full of oil and all kinds of debris.
Before we begin the boating season I finish a long comprehensive boatwide maintenance routine with a bilge cleaning. This consists of cleaning with a detergent (I like Roll-Off) a brush and rinsing with a hose. After flushing lots of water through the bilge and testing all pumps I vacuum the bilges to be sure everything is clean. Finally I physically inspect pumps for debris and electrical connections are visibly inspected.

The pumps I have seen fail have all failed for one of two reasons. Debris in the impeller locking the shaft will cause a pump to melt down. This is obvious when you see it the pump literally changes shape it gets so hot.

The second failure I have seen is water egress in the wires due to a faulty installation. The water will wick its way down the wire all the way to the pump with predictable results. I always use clear heatshrink butt connectors of the proper size on connections and I am sure to keep those well above expected water levels. Inspection includes looking and giving the wires a soft flexing. A leak will be apparent...

Restrictions in hose do limit the output of a bilgepump, something that is a very important consideration in understanding how that pump might be used. That is a subject worth having a discussion about.

For the record, the only pump I have ever owned that failed was due to a piece of wire that locked the impeller. The pump suffered a locked rotor failure and drained the battery of the little sailboat it was installed in. The pump was properly fused but that did not help...

That was almost 30 years ago and I have kept the cleanest bilge anyone has ever seen from that day on...
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Old 01-17-2017, 07:55 AM   #43
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Greetings,
Slight thread drift. One other advantage of a clean bilge is it allows one to quickly spot any new leaks (particularly engine/transmission fluids). Back to pumps.
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Old 01-17-2017, 10:21 AM   #44
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As a professional mariner, salvage master and marine surveyor, my 40 years experience in the marine business and investigation of literally hundreds of sinkings and thousands of failures, I completely disagree with Jeffrey, and completely agree with Bruce B. Oh, and on commercial boats, any through hull discharge MuST have a non return valve or device by rule. Not a suction break, a device.
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Old 01-17-2017, 10:45 AM   #45
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I completely disagree with Jeffrey, and completely agree with Bruce B.
I'm not doing my job if you're only agreeing with me. I must be the most successful guy in existence that gets everything wrong so often.

We sort of were saying different things. I don't disagree about debris causing pump failures. I was saying that hose size is leading to poor pump life and it's something that I never hear about. That type of thing gets my attention - and most of the people who have read our newsletters and checked have been appreciative when it turned out...drum roll...they had the wrong size hose connected too. Unknowingly.

The design of putting a centrifugal pump at the bottom of the bilge is also problematic. A much better design uses two pumps - the centrifugal mounted higher than a diaphragm pump, neither having a check valve. Diaphragm pumps are made to handle debris so this design solves a bunch of failure problems.

Of course, that's probably wrong too...
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Old 01-17-2017, 11:09 AM   #46
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I'm not doing my job if you're only agreeing with me. I must be the most successful guy in existence that gets everything wrong so often.

We sort of were saying different things. I don't disagree about debris causing pump failures. I was saying that hose size is leading to poor pump life and it's something that I never hear about. That type of thing gets my attention - and most of the people who have read our newsletters and checked have been appreciative when it turned out...drum roll...they had the wrong size hose connected too. Unknowingly.

The design of putting a centrifugal pump at the bottom of the bilge is also problematic. A much better design uses two pumps - the centrifugal mounted higher than a diaphragm pump, neither having a check valve. Diaphragm pumps are made to handle debris so this design solves a bunch of failure problems.

Of course, that's probably wrong too...
It kind of is wrong.
All diaphragm pumps have at least two check valves built in. While some are built with large valves designed to pass some debris, they can all get stuck open if the debris is big enough.

I do like the idea of using a diaphragm pump as the primary pump and a centrifical as the emergency pump.
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Old 01-17-2017, 12:45 PM   #47
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Jeffery's observation that pumps "burn out" due to having a restricted discharge may be simply due to the pump has to run longer to move the same amount of water.

A 3/4" hose has a cross section of 0.44 sq inches. A 1 1/8" hose has a cross section of 0.99 sq inches.

A restriction in the discharge causes the pump to move up on the affinity curve, creating more head, and less flow.

If the flow is halved, the run time is doubled.

My observation is that most small boat plastic bilge pumps are junk.
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Old 01-17-2017, 01:08 PM   #48
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Jeffery's observation that pumps "burn out" due to having a restricted discharge may be simply due to the pump has to run longer to move the same amount of water.
Adding one more observation from the guys who see this all the time...

If instead of replacing the hose/thru hull with the proper sized one (usually 1-1/8") they replace the pump with a smaller pump that is made to work with 3/4" outflow, the pump life extends greatly too. The specific finding was large 1500/2000 Rule pumps on 3/4" lines where the problem appears. That was why I suggested earlier that a smaller pump will often work better in many boats.

The fact is that a 1500 cannot push 1500 GPH through a 3/4" opening anyway so it's probably better to have a few smaller pumps sized correctly.

I totally agree that these pumps are junk. I just also think there is a relationship between centrifugal pump restriction and shortening motor life (windings? connections?) on these cheap motors even though it shouldn't happen with that type of pump. Perhaps with a really excellent pump, it wouldn't matter. With these mass produced, cheap bilge pumps, it seems like it does.

The only thing in boating worse than bilge pumps are the typical float switches. We switched to all USS switches for bilge and high-water alarms. They appear to have much more quality and you certainly hear better reports about them (even within this thread). I'm quite interested to see their lifespan on our boat. The typical elbow ones are incredible junk.
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Old 01-17-2017, 01:25 PM   #49
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[QUOTE=Jeffrey S;

I totally agree that these pumps are junk. I just also think there is a relationship between centrifugal pump restriction and shortening motor life (windings? connections?) on these cheap motors even though it shouldn't happen with that type of pump. Perhaps with a really excellent pump, it wouldn't matter. With these mass produced, cheap bilge pumps, it seems like it does.

The only thing in boating worse than bilge pumps are the typical float switches. We switched to all USS switches for bilge and high-water alarms. They appear to have much more quality and you certainly hear better reports about them (even within this thread). I'm quite interested to see their lifespan on our boat. The typical elbow ones are incredible junk.[/QUOTE]



Now this I can agree with. Now you are on the right track. A properly built centrifugal pump is the correct tool for the job. Also a well constructed float switch. Stuff you can buy at west marine doesn't cut it. Go look at commercial grade stuff from an industrial/marine catalog and you will find some good options.

Diaphragm pumps are not the best tool as primary bilge pumps and should not be in that service.

Back flow restriction valves (non return valves) built of a rubber diaphragm are crap. Use weighted bronze non return valves. You use bronze in your sea suction so don't you? Why not in the discharge end? And while in discussion, use proper piping, plastic hose is also crap and a potential failure point.
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Old 01-17-2017, 01:28 PM   #50
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And I do not doubt your success. I think your electronic products are excellent. But here you have wandered into a field beyond your area of expertise and your first post offered really bad advice.
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Old 01-17-2017, 01:50 PM   #51
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Now this I can agree with.
The world must be ending. This is one of the signs.


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Use weighted bronze non return valves. You use bronze in your sea suction so don't you? Why not in the discharge end?
No, I don't use a check valve in any part of "sea suction" or bilge systems - ABYC says to not use check valves in bilge systems. They end up adding too much head pressure and fail because of debris in bilge environments. I don't care what it's made out of - it's wrong to put them in.

Holy cow - what happens if ABYC agrees with me too? That must signify the end times.
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Old 01-17-2017, 01:52 PM   #52
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...and your first post offered really bad advice.
Can you please give the statement that was "really bad advice"?
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Old 01-17-2017, 02:57 PM   #53
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I think ABYC doesn't allow a check valve to be installed as an anti-siphon device.

I believe you can install a check valve as an anti backflow device.

This may also be in the form of a foot valve to assist in priming.

I also believe that ABYC standards are for DC powered submersible pumps.

I don't have my standards with me as I forgot my thumb drive at home. I may very well be wrong.
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Old 01-17-2017, 05:20 PM   #54
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I'm not doing my job if you're only agreeing with me ...
Indeed. Hard at work.
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Old 01-17-2017, 05:49 PM   #55
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You are correct. A check valve may be used to prevent a pump from short cycling due to back flow but not as anti-siphon protection. It is found in ABYC H-22, 22.8.9.

Quote:
Originally Posted by Northern Spy View Post
I think ABYC doesn't allow a check valve to be installed as an anti-siphon device.

I believe you can install a check valve as an anti backflow device.

This may also be in the form of a foot valve to assist in priming.

I also believe that ABYC standards are for DC powered submersible pumps.

I don't have my standards with me as I forgot my thumb drive at home. I may very well be wrong.
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Old 01-17-2017, 06:26 PM   #56
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You are correct. A check valve may be used to prevent a pump from short cycling due to back flow but not as anti-siphon protection. It is found in ABYC H-22, 22.8.9.
ABYC H-22.7(e) discourages the use of backflow devices in bilge systems. This conflicts with H-22.7(g) which says a checkvalve, "can, if necessary" be used for pump cycling. That's a shame because it's giving some permission to use something that isn't needed when better design would solve the need instead. Still, the "if necessary" clause implies that it's not the first thing to think about using.
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Old 01-17-2017, 07:31 PM   #57
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I am going to weigh in on this.
Bruce
Thank you for bringing us back from the academic world with actual examples and advice
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Old 01-18-2017, 07:38 AM   #58
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Can you please give the statement that was "really bad advice"?
Crickets...
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Old 01-21-2017, 04:10 AM   #59
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Don't feed the troll.
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Old 05-12-2017, 08:02 PM   #60
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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.

And increase wire size of the feed. A more powerfull pump to move more water will have a bigger motor which will draw more current which will produce more Vdrop in the original wire which will cause the motor to run slower and move less water, run hotter and likely cause a frequently operating pump to burn out sooner..
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