Y together two bilge pumps?

[Tom.B]

Our boat has two bilge pumps, both with their own above-the-waterline thruhull. However, the factory didn't really put the pumps in the three places where the water sits when the boat is at rest. Basically, slightly forward of the pump and slightly aft of the same pump. Sooooooo... I want to move the current one more forward and add another one more aft under the master berth (using one of those small Whale pumps with the remote pickup). This is primarily to remove the water that never leaves the boat (rain water that gets in the hatch) because I do have plans to add yet another Haus Daddy pump for emergencies in the near future. Anyway, for the forward pump, would it be okay to "Y" the two outputs together for the time being? Running a new hose for the new pump is going to be a HUGE PITA and I would like to tie that job to another future project rather that having to go thru the entire ordeal twice. I get that it will probably hurt the total capacity and that a check valve or two might be needed, but am I missing anything here?


EDIT* The other option, I suppose, is to use a very small bilge pump and pump it into the shower sump and let the sump take it overboard.

 

[psneeld]

Removing the final bits of water with bilge pumps to me is not the way to go.

For my whole recreational and pro career...I never really gave the dri-bilge concept a second thought.

Once I saw the DIY projects here and on YouTube, I had everything on hand except the $30 pump. So I tried one out.

Never been happier and never had a dry bilge like now.

The beauty of the setups is they can be rigged for multiple pickup stations and not the complexity or expense of the larger bilge pump setups that will still never get all the water out.

Sure adding bilge pumps with check valves can be done but I would never T in with check valves. Either connect them past the loop that drains overboard or make one tiny and pump it into a sump like a shower sump that pumps overboard.

 

[OldDan1943]

Do NOT put a Y in your bilge pump overboards. Dont consider a check valve in your overboards.
One bilge pump, one overboard. Two bilge pumps, two overboards.
End of story.

 

[DavidM]

I agree with OldDan. The running bilge pump will send water back through the other one when it is off unless you install check valves and check valves in bilge hose are fundamentally unreliable.

David

 

[Nick F]

i agree with olddan. The running bilge pump will send water back through the other one when it is off unless you install check valves and check valves in bilge hose are fundamentally unreliable.

David

+ 10 !

 

[Comodave]

If it is just mopping up a little bit of water, maybe something like a Dry Bilge system. Run it’s output to the shower sump. I bought one for the last boat but sold the boat before I got it installed.

 

[Tom.B]

Thanks everyone

 

[OldDan1943]

Perhaps we/me should have started out with, "Why is isn't your bilges dry now?"

 

[Marco Flamingo]

I've only recently been made aware of the "dry bilge" concept. It apparently isn't a thing in the wooden boat community. I suppose it would be possible with a fiberglass boat, but I'm still unsure of the intended benefit.

Right now, I have water sitting in the toilet bowl at the house. Been that way for years. It isn't an issue unless, of course, there's something in there besides just the water. Why is water sitting in the bilge an issue? It isn't gray/black water, right?

 

[hollywood8118]

I've only recently been made aware of the "dry bilge" concept. It apparently isn't a thing in the wooden boat community. I suppose it would be possible with a fiberglass boat, but I'm still unsure of the intended benefit.

Right now, I have water sitting in the toilet bowl at the house. Been that way for years. It isn't an issue unless, of course, there's something in there besides just the water. Why is water sitting in the bilge an issue? It isn't gray/black water, right?

It promotes " boat funk" smell
Hollywood

 

[Tom.B]

Once I saw the DIY projects here and on YouTube, I had everything on hand except the $30 pump. So I tried one out.

Never been happier and never had a dry bilge like now.

I am going to give this a go. Seems cheap and easy.

 

[Fish53]

I'm assuming the USCG not allowing bilge pumps to share an overboard discharge on inspected vessels has some reason?

 

[psneeld]

Not sure the USCG regulates anything about or even requires bilge pumps. 33CFR183

 

[Gdavid]

Not sure the USCG regulates anything about or even requires bilge pumps. 33CFR183

I assume he is talking about inspected vessels

 

[psneeld]

I assume he is talking about inspected vessels

Sorry, now rereading his post I see where he might be headed.

Yes Fish....sharing bilge pump outlets are probably a bad idea and the USCG most likely disallows them on inspected vessels....yet ....I think some years, Sea Ray glassed in a huge overboard discharge manifold that had many onboard discharges dump into it. It may eventually blended with an oversized exhaust outlet through the transom. Seemed to work great, lessened though hulls probably for looks as much as anything, and I never heard of an issue with that concept...

But hoses, y's and check valves sound like a bad idea.

Here is the CFR link for commercial vessels and it isn't clear on the y issue with my quick read, but still not likely approved in my mind.

https://www.law.cornell.edu/cfr/text/46/182.520

 

[Fish53]

Not sure the USCG regulates anything about or even requires bilge pumps. 33CFR183

Inspected vessels are in title 46, small passenger vessels with more than one bilge pump are required to have a discharge manifold and depending on the size vessel in question number, type and discharge size is stipulated. Generally on inspected boats carrying more than six passengers most inspectors take a dim view of the common Rule type pumps although it isn't stated in CFR.

 

[Fish53]

Sorry, now rereading his post I see where he might be headed.

Yes Fish....sharing bilge pump outlets are probably a bad idea and the USCG most likely disallows them on inspected vessels....yet ....I think some years, Sea Ray glassed in a huge overboard discharge manifold that had many onboard discharges dump into it. It may eventually blended with an oversized exhaust outlet through the transom. Seemed to work great, lessened though hulls probably for looks as much as anything, and I never heard of an issue with that concept...

But hoses, y's and check valves sound like a bad idea.

Here is the CFR link for commercial vessels and it isn't clear on the y issue with my quick read, but still not likely approved in my mind.

https://www.law.cornell.edu/cfr/text/46/182.520

I agree it does sound like a bad idea, probably because it is. One of the things I dislike about centrifugal pumps is water can go through them either way, in essence it's a hole in the side of your hull leading straight to the bilge. That's why I use diaphragm pumps and Ultra switches, I also have an 1 1/2" manual diaphragm pump. I'm not too excited about the through the exhaust idea, if you did you'd want a raised syphon break at least several inches above the exhaust elbow.

 

[rslifkin]

Manifolding diaphragm pumps to a sufficiently large output is safe. I wouldn't do it with centrifugal pumps unless there's no choice and a significant vertical drop from the high point in the hoses to the manifold.

 

[Fish53]

Manifolding diaphragm pumps to a sufficiently large output is safe. I wouldn't do it with centrifugal pumps unless there's no choice and a significant vertical drop from the high point in the hoses to the manifold.

Most of the overboard bilge discharge manifolds I've seen have lower and much larger discharge point than the bilge line connections so water can't back up an open unused line. The idea of course is you only open the line or lines currently in use. I'm sure you saw my views on centrifugal pumps.

 

[rslifkin]

Most of the overboard bilge discharge manifolds I've seen have lower and much larger discharge point than the bilge line connections so water can't back up an open unused line. The idea of course is you only open the line or lines currently in use. I'm sure you saw my views on centrifugal pumps.

Valves on a bilge pump discharge (manifold or otherwise) is entirely unsuitable in my mind. If the pump can't be made automatic or I can't just flip a switch to turn it on, it better be a last resort emergency pump and nothing less. Otherwise it's worthless as a bilge pump.

 

[Fish53]

On larger vessels all bilge piping has valves and like fuel shutoffs, which we should all have, are accessible from an open deck. Obviously in the type use we're talking about here at least one automatic pump would have it's valve open. I'm not advocating a manifold setup but an individual discharge for each pump anyway. If you have a properly installed and functioning bilge alarm the assumption is you could address the pump issue in plenty of time, especially with the limited capacity of most common bilge pumps. If you can't with those capacities you're going to lose the boat anyway.

 

[psneeld]

Valves on a bilge pump discharge (manifold or otherwise) is entirely unsuitable in my mind. If the pump can't be made automatic or I can't just flip a switch to turn it on, it better be a last resort emergency pump and nothing less. Otherwise it's worthless as a bilge pump.

Manifolds on bilge pump intakes are common on commercial smaller vessels and ships.

I think often they are mandated by the USCG. See the link I posted.

Valves are required on discharge thru hull too in many cases.

 

[High Wire]

I agree with OldDan. The running bilge pump will send water back through the other one when it is off unless you install check valves and check valves in bilge hose are fundamentally unreliable.

David

Agree 100%. My current center console boat came with 2 bilge pumps tied together with a tee. Which ever pump started first just just blew out the others suction strainer until the second pump kicked on. Then both pumps shot a truly impressive stream several feet out the hull side. The knuckleheads that installed it also used the same fuse to power both pumps. I went back to only one reliable pump and has been trouble free for seven years now.

 

[rwidman]

Do NOT put a Y in your bilge pump overboards. Dont consider a check valve in your overboards.
One bilge pump, one overboard. Two bilge pumps, two overboards.
End of story.

This is the correct answer.

 

[stubones99]

If you are trying to get the last little bit of water in the bilge, you'll need a diaphragm or peristaltic pump, since they have valving to prevent backflow when the pump shuts off.
One DIY project I saw uses a timer and a peristaltic pump which is a low volume pump but will self prime and won't let the bilge water run back down the pump when you shut it off.

The downside is you need a decent filter on the inlet so debris won't ruin the pump tubing or valves. Unless you use a electronic water sensor, you'll probably have to run the pump on a timer, cutting it on for a minute every few hours.
https://www.amazon.com/Peristaltic-Pump/s?k=Peristaltic+Pump

 

[OldDan1943]

My N46 had a diaphragm bilge pump aft with the small strainer, very expensive.... Changed it out to a large capacity Rule.
It also had a manually operated diaphragm pump.

 

[cks]

One port for each pump.
Just last weekend my friends raw water engine pump fitting failed. This resulted in a 1” hole from the seacock through 5’ of hose directly filling the boat. Thank goodness the bilge pump kept up. If there was any other issues the one bilge outlet from two pumps would fail to keep up.

 

[Bacchus]

There are a few places that Mainship installed a manifold for overboard drain discharge. In all cases the hoses are routed to a high spot well above the manifold and it seems to work well... never had a problem.
All bilge pumps have separate hoses & thru hulls as they are relatively far apart.

 

[Fish53]

Manifolds on bilge pump intakes are common on commercial smaller vessels and ships.

I think often they are mandated by the USCG. See the link I posted.

Valves are required on discharge thru hull too in many cases.

Most larger vessels are to some extent depending on size compartmentalized and carry ballast. It makes more sense to have a single place for an engineer to control suction, discharge and transfer to/from various tanks and compartments. I've run a lot of fishing vessels that weren't inspected that nonetheless were set up like this simply because it makes sense, but yes on inspected vessels it's mandated.

 

[FF]

"I suppose it would be possible with a fiberglass boat, but I'm still unsure of the intended benefit."


Bragging rights , like my deck cleats are bigger than yours!