Bilge Pump Non-Return Valve

[waterdancer]

Originally Posted by Dockhead

Anybody have an opinion on diaphragm pumps versus the Supersub? I am inclined toward the latter, since it pumps much more (1100 gallons per hour nominally) and is much cheaper. Any reason why the much more expensive diaphragm pump would be worth the money? The new Supersubs are logic controlled, too -- looks like a nice unit perfect for this purpose. I would put one of them in place of the small original bilge pump.

This installation of a diaphragm pump calls for a check valve at the end of the hose, where the strainer is. This helps the pump to prime easier, since the water does not flow back immediately, but will not prevent the water from the hose eventually from flowing back into the bilge. Hopefully, thi swill be a small diameter hose (1/2 inch or so) so the water volume flowing back is minimal.

I like diaphragm pumps, such as the Whale Gulper 220 that allow bilges to be pretty dry, but they are only maintenance pumps, and should not be relied on as the main defense mechanism. As others mentioned, if you can not change the position of the float, mount the entire pump on a block and use a diaphragm pump with a check valve to suck the bilge dry.
Another advantage of the diaphragm pump is that if the strainer is not solidly mounted, you can actually move it around in the bilge to suck out the water when the boat is heeled.

[psneeld]

Originally Posted by Blue Stocking

Take a look at an old Penn Yan, 14-16ft, with a molded in floor, and a small sump under the engine. You'll see what I meen.

ingenuity....

[rlmmail]

Originally Posted by psneeld

never inferred that wasn't an issue... but no boat should rely on one pump...that's a newbie issue so I didn't address it...bact to my ststement about listening to the people in the know...not necessarily what you learn from bosatshows and internet forums....

But it's also a *different* issue. I agree about the need for more than one pump. But an unattended boat could have fifteen pumps and they would all be useless of the batteries were dead because of one of them.

You seem to be insisting that certain "people in the know" always agree on the issue. I wish life were that simple, but clearly it isn't.

[Cheechako]

Originally Posted by rlmmail

Again, it's not a matter of manufacturers vs. lifelong cruisers--clearly there are members of *both* groups are on *both* sides of this issue. That kind of "analysis" clearly cannot resolve the issue.

What I'm wondering is whether there are empirical examples of a boat sinking or being endangered because of a failed check valve?

I can give you one example of a boat nearly sinking when it DIDN'T have a valve... mine! Caught it with water to the floorboards... I think the odds of other bilge pump issues are much higher. Havent we all experienced stuff getting in the bilge pump? A couple of years ago I bought a bilge pump off Ebay that the seller said had been tested. It did spin, but didnt pump because there was a couple of feet of 1/8" cord wrapped around the impeller inside the cage. I think one's effort should be used toward a protective cage around the pump before worrying about a check valve.... even if you are fastidious about your bilge, once the water gets up to the floor boards, pieces of stuff can come from anywhere....

[rlmmail]

Thanks, Cheechako. I wasn't expecting to hear this kind of example, but it does make sense, and I'm glad to know it! Did your boat have the usual other precautions (vented loop, enough distance between bilge and outlet, etc.)? Have you noticed any serious reduced pump capacity problems since installing a check valve? Thanks again.

[psneeld]

Originally Posted by rlmmail

But it's also a *different* issue. I agree about the need for more than one pump. But an unattended boat could have fifteen pumps and they would all be useless of the batteries were dead because of one of them.

You seem to be insisting that certain "people in the know" always agree on the issue. I wish life were that simple, but clearly it isn't.

but often they do....

[Cheechako]

I no longer have this boat. It originally had a very high loop up under the coaming, no vent. Because I installed a DC gen and made other changes I decided to re-route the new hose with a lower loop creating less "head" for the pump to push. It worked fine for a few weeks. Then one day while motor sailing, I just had this intuition.... not sure what clued me...maybe the motion of the boat.... but I pulled the bilge pump access floor board and the water was at the board! Evidently, the combination of the large bow wave at the stern quarter and the heel got a siphon going. Later I put the check valve in the horizontal part of the hose. Personally I would probably go for a real high loop if it's an option rather than a valve. But I wouldnt be afraid to use a valve at all. A light that shows when the BP is operating could be a lifesaver. Even the big bilge pumps dont really put out a lot of water... it's amazing how long it took me to empty that bilge.... even though the stream looked real strong coming out of the hull..
Moral to this story? If it aint wrong dont fix it!
Since this experience I have often had two large bilge pumps on my boats. Large Diapragm pumps have a check valve in them and they are supposed to be the "storm" solution due to the volume they put out, (until your arm give out! ha!) so I wouldnt be afraid of a valve.

[psneeld]

Originally Posted by Cheechako

I can give you one example of a boat nearly sinking when it DIDN'T have a valve... mine! Caught it with water to the floorboards... I think the odds of other bilge pump issues are much higher. Havent we all experienced stuff getting in the bilge pump? A couple of years ago I bought a bilge pump off Ebay that the seller said had been tested. It did spin, but didnt pump because there was a couple of feet of 1/8" cord wrapped around the impeller inside the cage. I think one's effort should be used toward a protective cage around the pump before worrying about a check valve.... even if you are fastidious about your bilge, once the water gets up to the floor boards, pieces of stuff can come from anywhere....

how did NOT having a check valve affect that situation???...you mention junk in the bilge...another potential issue to make a check valve irrelavent (check valves are usually designed for clear water usage...never true of a bilge....

OK saw your next post...but a check valve wasn't the best answer...the best answer is a properly desighned bilge pump system....

[psneeld]

Originally Posted by Cheechako

I no longer have this boat. It originally had a very high loop up under the coaming, no vent. Because I installed a DC gen and made other changes I decided to re-route the new hose with a lower loop creating less "head" for the pump to push. It worked fine for a few weeks. Then one day while motor sailing, I just had this intuition.... not sure what clued me...maybe the motion of the boat.... but I pulled the bilge pump access floor board and the water was at the board! Evidently, the combination of the large bow wave at the stern quarter and the heel got a siphon going. Later I put the check valve in the horizontal part of the hose. Personally I would probably go for a real high loop if it's an option rather than a valve. But I wouldnt be afraid to use a valve at all. A light that shows when the BP is operating could be a lifesaver. Even the big bilge pumps dont really put out a lot of water... it's amazing how long it took me to empty that bilge.... even though the stream looked real strong coming out of the hull..

horns are better than lights for high water...often you may not notice a light...

you are right about 12v bilge pumps...and most don't pump ANYWHERE near capacity for a lot of reasons....check valve could be one of those reasons..... a gas powered trash pump is your best defense against flooding...other than normal damage control.

[Blue Stocking]

Just as a bit of an aside,-- for a period of time I ran a Navy surplus 48 ft LCU, with the bow opening door.
Powered by Grey Marine 6-71s, some of the raw water from each engine dumped directly into the engine room bilge, to be constantly scavenged by engine/belt driven rotary-vane pumps, because the door had no seals.
Pumped out on side decks, so you could always see your discharge.

[waterdancer]

Protective Cage: A must. I had a fire on one of the bilge pumps because a washer got stuck in the impeller, because there was no cage and the fuse was too high so it did not blow.

High Capacity Bilge pumps:
There is a caviat. These bilge pumps sometimes can start cavitating, and will not pump the water untill you can turn them off and then on again. Several times I waited for a while, hoping that the build-up of the pressure on the bilge water would get the pumping going, but it would not. The moment I stopped the pump, by pushing the float valve down, it started pumping.
It seems to happen if the pump starts spinning too soon and there is a rush of water. Anybody have any insight to this ?

[Capitain Mike]

Originally Posted by rlmmail

Thanks, Cheechako. I wasn't expecting to hear this kind of example, but it does make sense, and I'm glad to know it! Did your boat have the usual other precautions (vented loop, enough distance between bilge and outlet, etc.)? Have you noticed any serious reduced pump capacity problems since installing a check valve? Thanks again.

Having nearly had my boat sink. reasons below.

INCORRECTLY FITTED vOLVO STERN GLAND. FITTED BY A COMPANY IN LEKAS LEFKADA Greece.

The company shall remain nameless for legal reasons. all I will say is the company carries out yacht services is run by an English man and is very close to the public berths and the floating restaurant.

NRV can stick open or closed in either situation it not a good idea to have them.

As you see in this thread there are several major manufacturers who though they manufacture then do not recommend NRV I am adding to the list Rule/Jabsco. see my post #21

http://www.cruisersforum.com/forums/...tml#post697860

I have a Wind Gen a Solar Panel and excellent batteries and my boat was supposedly being monitored while I was away. On arriving at the port by ferry at 4am and checking on the boat I found myself knee deep in water because of floating rubbish on top of one pumps float switch. Rubbish left in the bilge by the afore mentioned company. A second pump had a failed float switch a TMC TMC-08121 Automatic Float Switch and a third pump had a blocked Jabsco/Rule/ITT NRV.

So I bailed out with a bucket until I could see the pumps. Wife holding a torch and standing in the cockpit at the companion entrance the water being thrown out into the cockpit to drain away through the cockpit drains.

Welcome to JabscoShop - Jabsco & Rule Pumps and more - from the experts

I would advocate scrupulously clean bilges (as far as you can go). If you want to be serious put a pump over the side and fill the bilges with water and see what is floating about, Gel coat chips separated from the hull, paper, matchsticks, all sorts of plastic, including electrical tape, washers, wire strippings, labels, cable ties toothpicks you name it and if you have kids well there is a lot more can be down there. Scrape as much as you can up by hand then pump the water out using all the pumps at the same time, the loose crap will congregate around the pump strainers, so keep them clear.
It would not hurt to carry out the operation twice. ( I thought my bilges were clean!!!!! UNTIL IT HAPPENED)

When you are carrying out work internally in the boat make sure all rubbish goes straight into a rubbish bag as you make it, DON'T clean up later. Keep the under side of the floor pan opening edges clean. When you sweep up the rubbish goes between the GRP and the wood.
secure the float switch to the bilge bottom then raise the pump above the water level returned to the bilge when the pump stops.

If the pump is an all in one pump and float switch fit it on a raised block or bracket above the feedback water level if you want it dry fit a sump strainer and pump also/ Or use a sponge and bucket once it is all out it should remain dry.

Many pumps have a fitting where the float switch is fitted on a level with or slightly lower than the pump.

Most pump manufacturers can supply a side mount bracket for the smaller pumps Rule 66. Up to Rule 1100

Rule 66
Vertical Mounting Bracket
Fits all 'Round' Rule pumps from size 360 up to size 1100
Actual Weight: 0.04 Kg (Approx. 0.24 Kg packed)



Universal Pump Adapter
Allows all Rule 360 (1360), 500 (1893), 800 (3028) Round and 1100 GPH (4164 LPH) pumps to be mounted to competitive bases: Attwood® V-500, Mayfair Proline 500 (1893), 750 (2839), 1000 (3785) and West Marine 500 (1893), 750 (2839) and 1000 GPH (3785 LPH) models. Price $3.50
Rule Submersable Pumps AND ALL THE FITTINGS PIPES VENTED LOOPS THAT YOU COULD NEED.


JOHNSON PUMP 10605 CARTRIDGE SIDE BRACKET

PLEASE NOTE THE PICTURE FOR THE JOHNSON IS UPSIDE DOWN THE PUMP REALLY FITS ONTO THE LARGER SECTION AND HAS 5 PUMP FIXING HOLES. 4 ALREADY PREDRILLED.


Usually available world wide

You will have to find the rest yourselves.

I like the Johnson because you can use other pumps fitted to the base.

If you are talking about vented loops then don't forget the sink wastes, the toilet, shower tray, water tank breathers central heating and air con vents and any other ingress or exit but usually these are for a heeling vessel. If your siphoning back in from your bilge pumps then sort the bilge pumps float switches etc.

You can join to Bilge pump pipe outlets but only at the through hull connection and the through hull should be twice the diameter of the bilge pump tubes. If your worried then raise the pipes above the level of the through hull fitting. (Note you can use any brass that has been de-zincified.
http://www.aquafax.co.uk/aquafax_v2/...s/TechData.pdf

Please note all you Volvo Stern Gland users (Volvo call it a Rubber Packing box) who complain that there stern gland leaks rest assured its not fitted, greased, burped or maintained correctly. After refitting a new one myself I can safely say that THERE SHOULD BE NO LEAK OR DRIP AT ALL.

P.S. Don't forget if you have a pump on your shower tray a manual override switch gives you another pump in an emergency.
Every reduction in pipe internal diameter restricts the flow keep the runs as short as possible and the the pipe section to the through hull as vertical as possible.

Every little helps
THE HULL IS THERE TO KEEP THE WATER OUT IF ITS COMING IN THE BILGES AND ITS NOT RAIN WATER YOU HAVE A PROBLEM. I hope this helps took me a long time to type with one finger.

[Capitain Mike]

Originally Posted by psneeld

horns are better than lights for high water...often you may not notice a light...

you are right about 12v bilge pumps...and most don't pump ANYWHERE near capacity for a lot of reasons....check valve could be one of those reasons..... a gas powered trash pump is your best defense against flooding...other than normal damage control.

You are right about the light,
I like the horn idea how about a 3 tone car horn. No I'm not joking
And how about a separate float switch that does nothing but turn the horn on ???

[Maine Sail]

Originally Posted by rlmmail

My question was whether anyone knew of actual cases where a boat sank or was endangered because of a failed check valve? Thanks.

How about my own brothers boat many years ago. I know of a couple others too. My brothers Mako sank because the check valve stuck and the bilge could no longer pump and it also eventually killed the batteries. This was a 24 foot walk around with outboard but still it sunk due to a stuck check valve.

In the aftermath we discovered that the bait well seacock made of PVC and threaded over a bronze thru-hull, another STUPID manufacturing mishap, failed/cracked and was weeping pretty badly. He never knew it and when the check valve stuck on the bilge pump it kept weeping.

I you think some sailboats are built poorly you should see some of the center console and walk around fishing boats. Slapped together does not even begin to describe how poorly some are built. Even ones with "stellar" reputations in that market can be scary.

Once we had it in the driveway on the trailer we installed new batts and filled the bilge with water, nothing, and the pump was simply cavitating. Manually flipped the switch on and off to try and get it moving or to prime, nothing, removed the check valve and found is stuck. re-routed the hose right to pump and whoosh pump began moving a torrent of water. This was a very short lift too and was not due to the weight of the water behind it in the hose the valve just stuck. Lucky for us it was a two stroke engine and easily fixed. His boat had zero need for a check valve, but it still had one.

[sdowney717]

strainers that I roll out of Monel screen wire

Blue Stocking, where do you get monel screen?