Bilge pump debate

[lipets]

Surprised no one yet brought up the use of fabricating an discharge manifold rather than several thru hulls for several pumps


Thinking about a one 2" thru hull with a manifold to accept several pumps


Anyone research or make one?


You can push a lot of water out a 2" hole

 

[SteveK]

Surprised no one yet brought up the use of fabricating an discharge manifold rather than several thru hulls for several pumps


Thinking about a one 2" thru hull with a manifold to accept several pumps


Anyone research or make one?


You can push a lot of water out a 2" hole

One thing I read was multiple lines allow a back feed event.

 

[rslifkin]

My current plans involve some manifolding to avoid needing to punch additional holes in the boat. 2 of my current close-together sink drains are going to be manifolded together onto a 1.5" discharge, freeing up another 1.5" discharge for the big 3700 gph pump.

And the aft head sink discharge is also 1.5", so provided I can test and confirm that there's enough vertical rise to avoid backing water up into the sink, the 1 1/8" discharge from the 2000 gph pump will get Y-ed into that sink discharge (on a vertical section of the run just before the fitting).

When sharing thru hulls, total flow capacity needs to be considered, as well as any potential back-flow issues and whether sharing leads to longer hose runs (with corresponding reduced flow).

 

[lipets]

Add an anti siphoning loop?

 

[angus99]

My current plans involve some manifolding to avoid needing to punch additional holes in the boat. 2 of my current close-together sink drains are going to be manifolded together onto a 1.5" discharge, freeing up another 1.5" discharge for the big 3700 gph pump.

And the aft head sink discharge is also 1.5", so provided I can test and confirm that there's enough vertical rise to avoid backing water up into the sink, the 1 1/8" discharge from the 2000 gph pump will get Y-ed into that sink discharge (on a vertical section of the run just before the fitting).

When sharing thru hulls, total flow capacity needs to be considered, as well as any potential back-flow issues and whether sharing leads to longer hose runs (with corresponding reduced flow).

Just a thought: is your sink through hull at or just above the waterline? If so, you may be pumping against considerable back-pressure if the boat settles a bit and blast some of that water up through the sink drain.

 

[SteveK]

Add an anti siphoning loop?

yes that would work unless pumped water goes past. Maybe a back flow valve?
anyway it came up a few times in articles with thumbs down.

 

[rslifkin]

Just a thought: is your sink through hull at or just above the waterline? If so, you may be pumping against considerable back-pressure if the boat settles a bit and blast some of that water up through the sink drain.

My drain thru hulls are all a few inches above waterline. That's a good point about what might happen if the boat were to settle down far enough in the water. Might need to look at popping an extra thru hull in there this winter to keep the 2 separate.

 

[AusCan]

Yeah, the mat has its uses but I’d feel better with a variety of tools.

Nice selection of tools.
You never know what you'll be dealing with. Having many options readily available is the key.

 

[wkearney99]

NERF footballs are very soft closed cell foam toy football
Great stuff foam
Truplug
soft wood plugs
toilet bowl wax

Never underestimate the value of spare pillows and foam mattresses. Those jammed into holes can buy you precious time to arrange other fixes and seek help via the VHF.

 

[Bud]

We have three bilge pumps with float switches. The main pump is the lowest, the next highest has a alarm hooked to it so if it comes on it also sounds the alarm to let you know that either something is wrong with the first pump or it is not keeping up. Then I also have a T valve in the suction side of the a/c pump (1hp for multiple units) so the pump can be used to pump the bilge.

Bud

 

[psneeld]

As in all true survival situations....preparation, initiative, creativity, and the will to live are all important ingredients.

 

[Lou_tribal]

As far as I'm concerned, total automatically controlled bilge pump capacity on a boat should approximately equal the water ingress from a failure of the largest underwater fitting (typically a shaft log or engine intake thru hull).

I would say that your pump capacity should match your potential water ingress, murphy's law applied. If you have 4 underwater fittings expect all of them to fail at the same time, match the water ingress, and add 50% (or more) for good measure if one of the pump burns.

But as a general guideline I would say that this is the typical domain where more you have, better you are.

As an example one day a raw water hose popped out in my ER, the pump was able to cope with the water ingress but just enough, it was a traumatic experience to see a feet of water down there. This is something I need to improve!

L

 

[syjos]

As in all true survival situations....preparation, initiative, creativity, and the will to live are all important ingredients.

I agree 100%

Add to that a calm demeanor and "resilience in the face of adversity".

 

[syjos]

I would say that your pump capacity should match your potential water ingress, murphy's law applied. If you have 4 underwater fittings expect all of them to fail at the same time, match the water ingress, and add 50% (or more) for good measure if one of the pump burns.

But as a general guideline I would say that this is the typical domain where more you have, better you are.

As an example one day a raw water hose popped out in my ER, the pump was able to cope with the water ingress but just enough, it was a traumatic experience to see a feet of water down there. This is something I need to improve!

L

Here in the PNW, I size pumps for the worst case scenario, hitting a deadhead (logs floating submerged, just below the surface) or a submerged unmarked rock. Deadheads are not as prevalant now as they used to be with the current high cost of logs. But we still hear Coast Guard warnings about deadhead location on the VHF

We hope not to hit one, are real careful, but we plan for the worst.

Sandpiper, 40', 40,000# has 2 Rule 3,700's, 2 Rule 2,000, Rule 800 Shower Sump, and a Shurflo 180 diaphgram pump for sucking bilge dry. All thru hulls are equipped with easily accessible seacocks.

I also carry a 1/2 hp 120 VAC portable Little Giant submersible utility pump with hose for huge emergencies. It pumps 2 or 3 thousand gallons per hour.

 

[Searios]

hydraulic trash pump

If you have a hydraulic system then a hydraulic trash pump is a good option. Its basically an Ericsson Pump rebranded and connected to a hydraulic pump...Low maintenance and a fantastic performance,
https://www.fastflowpump.com/all-submersible-hydraulic-pumps

 

[FF]

NICE , even the smaller pumps are 550-600 GPM!

 

[BlindHog]

Lots of great comments. If you want to slow your sinking, which seems to be the point of your post, then I would look at installing a bilge pickup to your water intake on your main(s). Lots of sportfishermen are built this way today - look at cabo, viking, hatteras, etc. Your mains can pump a lot of water with a high rpm to slow the inevitable. Not sure where you travel or how you use your boat, but I would invest my time and energy in a good high quality water alarm first as most trawlers are inland and occasional coastal cruisers.

Also keep in mind going to a larger pump will mean more standing water as the larger pumps can't always get that last amount out like a smaller pump can, unless you are simply increasing gph in the same pump model.

 

[rslifkin]

Lots of great comments. If you want to slow your sinking, which seems to be the point of your post, then I would look at installing a bilge pickup to your water intake on your main(s). Lots of sportfishermen are built this way today - look at cabo, viking, hatteras, etc. Your mains can pump a lot of water with a high rpm to slow the inevitable. Not sure where you travel or how you use your boat, but I would invest my time and energy in a good high quality water alarm first as most trawlers are inland and occasional coastal cruisers.

Also keep in mind going to a larger pump will mean more standing water as the larger pumps can't always get that last amount out like a smaller pump can, unless you are simply increasing gph in the same pump model.

Personally, I'd rather add a belt driven (clutched) pump to the engines instead of diverting the cooling water intake. Some of those pumps move even more water than the cooling pump (unless you have very large engines) and it avoids the risk of causing yourself an additional problem due to sucking up debris or running the cooling pump dry during an emergency.

For the water quantity, that's why a good bilge pump setup should involve multiple sizes of pumps. Small ones mounted low to keep things fairly dry, then big pumps with the floats up higher to handle any major water ingress.

 

[HopCar]

Personally, I'd rather add a belt driven (clutched) pump to the engines instead of diverting the cooling water intake. Some of those pumps move even more water than the cooling pump (unless you have very large engines) and it avoids the risk of causing yourself an additional problem due to sucking up debris or running the cooling pump dry during an emergency.

For the water quantity, that's why a good bilge pump setup should involve multiple sizes of pumps. Small ones mounted low to keep things fairly dry, then big pumps with the floats up higher to handle any major water ingress.

Why not do both? I agree a belt driven pump will be preferred but it costs almost nothing to rig the engine cooling pumps to pump the bilge. When properly done, the water will be going through your sea strainers which should protect your engine.

I was once on a big sport fish boat that was sinking. The 1500 gph Rules installed by the builder were totally inadequate. The engines had nice 2” cooling pumps. I was about to close the seacocks and cut the hoses when the Coast Guard showed up with a nice big trash pump.

 

[SoWhat]

A hose falling off a 1" through hull 2' under the water line will result in 1800gph flowing in. Sounds like a 2000gph bilge pump will be perfect. But....

Voltage drop may reduce the power of the bilge pump, and then pumping water up and out causes an additional reduction in capacity, and finally corrugated tubing with numerous bends reduces capacity even more. Your 2000 gph bilge pump might be maxed out at 1000gph. Great. Buy 2 bilge pumps for 4000 gph. But....

You may be able to keep up with the intake of water if your batteries are in good shape but your bilge may have a few hundred gallons floating around before the auto switches turned on (if they work). So your actual dewatering capacity might be 2000 gph with 2 pumps. You might be able to keep up but you won't be able to reduce the amount.

I think bilge pumps are great for removing rain water, might be able to handle a hose coming loose, but are not designed to handle hull damage. I think having double the potential ingress volume is OK. In other words 2 4000gph pumps would be adequate. I have 2 1750's and carry a spare 2000 pump with plug and hose attached that I could direct into sink or overboard if required. I'm guessing I can buy enough time to find the broken hose and close the right seacock.

Anything more, I'm in the dinghy.

 

[rslifkin]

The idea isn't that the bilge pumps can keep up indefinitely or keep the boat dry with a major leak. The idea is for them to keep the flooding down to a manageable level for a period of time so you can find and reduce the leak. The further under water the leak gets, the harder it is to find it and do something about it. And the bigger the mess and more secondary water-induced problems you'll have to deal with after.

 

[lipets]

Just follow up on my latest thinking.


crawling around in the lazarette under the cockpit I see two cockpit drains on port and two more on starboard


each pair connect to their own 3" pipe out to a three inch thru hole


( so this on on both sides)


I was thinking about using that pipe as a manifold


hooking up a Johnson 4000 mid bilge wired to the house batteries 8 6volt bank plenty of amps there even without the engines running


or hookup two one on port one or starboard


what do you guys think about that plan

 

[syjos]

Just follow up on my latest thinking.


crawling around in the lazarette under the cockpit I see two cockpit drains on port and two more on starboard


each pair connect to their own 3" pipe out to a three inch thru hole


( so this on on both sides)


I was thinking about using that pipe as a manifold


hooking up a Johnson 4000 mid bilge wired to the house batteries 8 6volt bank plenty of amps there even without the engines running


or hookup two one on port one or starboard


what do you guys think about that plan

Maybe I misunderstood the question. Sorry if you have additional pumps in addition to the 4000.

I would not want to rely on one 4000 gph pump for the whole boat. Multiple pumps is good insurance when debris in the bilge could block the pump. Or the pump quits.

Also when taking on water, the boat may list or the trim may change from the additional weight. Having multiple pumps throughout the bilge will insure that one of the pumps will be in a position to dewater.

 

[seadragonbahamas]

Great thread here. Some really good setups posted for bilge pump systems.

My 2 cents worth on bilge systems would be.

Any boat over 25 feet and not foamed with positive flotation should have a minimum of 3 watertight compartments and preferably 5 compartments.

The bilge pump system should have two pumps per section that operate from two different seperated battery banks. They can be staged in switch water level activation height (and noted in a previous post the second pump switch can have an alarm).

I have had poor luck with pumps containing a self activated switch. When using one such as the Rule 1000 I put an extra external switch in the 3rd wire manual activation line (in addition to the manual switch).

The only bilge switch that I can highly recommend is the "Ultra Safety Systems" (Riviara Beach, Florida) "Ultra Bilge Pumpswitch" two versions with or without the alarm wireing. Top quality components with installed heat shrink waterproof butt connectors attached already for wiring. Select voltage 12volt, 34/32volt DC. These switches last nearly forever in commercial service.

Enjoy your boats.

 

[psneeld]

Warships are built to similar standards...


Good luck finding a 26 footer with 3-5 watertight bulkheads and 6-10 bilge pumps.


I agree that many should be built with separations high enough to not allow progressive flooding. However, the loss of space would limit a lot of boat usability/functional spaces and considering how few boats sink with reasonably good maintenance and captaining..... those requirements are a bit over the top in my mind.

 

[rslifkin]

Depending on how much space you've got between the cabin floor and the hull, bulkheads that at least greatly limit water flow between compartments may or may not be particularly intrusive to living space. They certainly don't have to be water tight more than a few feet up, as there's a certain threshold where you'll either have drowned everything that keeps the pumps running or will be running out of freeboard, at which point it just doesn't matter anymore.

 

[Gdavid]

A great tool and in my opinion, an underutilized one is a diagram of all thru-hulls in the boat, laminated and either briefed to the crew or posted in plain view. Resources like this are very effective at allowing passengers to assist in the event of an emergency and are helpful even for the owners who are likely to be in a state of panic. It is good practice to close seacocks not in use in heavy seas (best practice would be leaving them always closed except for in use, but who wants that hassle) but often the person with the closest knowledge of their location is otherwise occupied and doesn't want to leave the helm as conditions are deteriorating.

A good reminder to place on the diagram is to check the fresh water tankage levels. I have experienced a heavy leak from potable water tanks and it is very unnerving to realize how easily such a important resource can be lost, fortunately in my case it was inland cruising and a minor inconvenience, but there have been multiple instances of crews launching into a manic response, bailing out the bilges in a mad frenzy, only to realize they just pumped over all their fresh water.

 

[dhays]

A great tool and in my opinion, an underutilized one is a diagram of all thru-hulls in the boat, laminated and either briefed to the crew or posted in plain view.

That is a good idea. Thanks.

 

[steve Dublin]

A small 1" dia. thru-hull located 2 feet below the water line will let in 28 gpm. Your typical 500 gph bilge pump pumps out 8.3 gpm. Suggest you store some wooden plugs near each of your boats thru-hulls.
Cheers Steve Dublin
USCG 100 ton.

 

[Brooksie]

" The best bilge pump is a scared man with a bucket "