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Old 18-06-2014, 06:38   #1
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Installing 2nd Bilge Pump

Good sense is telling me put a float switch and bilge pump in a recent sailboat purchase that only has a manual bilge.

I would like to splice (Y connection) the hosing to the manual line near the outflow (so I won't need to cut any more holes in the transom) below the manual pump. I do have some questions, some may have common sense answers, so please forgive me:

1) Will triggering one pump result in negative pressure (sucking) on the other, possibly wearing out diaphragms or other mechanical components?
2) I realize flow rates will be reduced should (knock-on-wood) both be in use simultaneously. I'm assuming i should use a larger diameter hose downstream of the Y-connection to stop this. Are there any other ideas on how to add a second bilge pump that may be better?

Thanks.
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Old 18-06-2014, 07:01   #2
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Re: Installing 2nd Bilge Pump

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...I would like to splice (Y connection) the hosing to the manual line near the outflow (so I won't need to cut any more holes in the transom)...
Horrible idea.
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Old 18-06-2014, 07:28   #3
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Re: Installing 2nd Bilge Pump

I don't know why it would be a horrible idea, but my preference is truly independent systems without a single point of failure, in other words I'd drill another hole in the transom,
I already have 6, what's one more? 7 is a lucky number, right?
2 cockpit drains, one manual bilge, one electric, exhaust, shower bilge pump
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Old 18-06-2014, 08:45   #4
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Re: Installing 2nd Bilge Pump

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I don't know why it would be a horrible idea...
Because it could sink your boat.
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Old 18-06-2014, 09:15   #5
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Re: Installing 2nd Bilge Pump

Cut another hole up high on the transom. Mixing discharges is a bad idea if not done properly......a "y" is not properly
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Old 18-06-2014, 09:28   #6
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Re: Installing 2nd Bilge Pump

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Because it could sink your boat.
I do not think a Y is a good idea either, but I don't see how it could sink your boat. Will you elaborate?
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Old 18-06-2014, 11:00   #7
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Re: Installing 2nd Bilge Pump

Thanks for most of the responses. I'll go ahead and make separate systems.
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Old 18-06-2014, 15:25   #8
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Re: Installing 2nd Bilge Pump

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I do not think a Y is a good idea either, but I don't see how it could sink your boat. Will you elaborate?
Presumably the existing outlet is sized for the flow of the existing pump. Adding a T or Y and another pump to that outlet means that you are restricting the line and restricted to the use of only one pump at a time. When/if you really need the extra pump capacity, you're screwed. Also there is some danger of one pump back-flooding the other.

Whatever savings you think you're gaining, you aren't.
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Old 18-06-2014, 21:04   #9
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Re: Installing 2nd Bilge Pump

A long time ago (7 years) I posted here a similar question.

I proposed to put the Rule pump in series with the Whale pump.

Horrible idea. Heresy. Boat will sink. I will die.

7 years on each time I hit the Rule button it pumps out any water. Each time I wobble the Whale it pumps out any water.

I wouldn't consider a Y joint but series has worked fine for me.

I am all for redundancy - especially as one gets to bigger boats and more $$$ to protect. You appear to have a 24 foot boat. I have a 26 foot boat. For "complete" redundancy I have a couple of buckets on board - LOL...
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Old 21-06-2014, 17:10   #10
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Re: Installing 2nd Bilge Pump

That's the way my two pumps are rigged. Just be sure to have some rise in each line just before so the water goes out and not back into the boat via the other one. Works fine.
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Old 21-06-2014, 17:52   #11
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Re: Installing 2nd Bilge Pump

So you have, starting at the bilge, the Rule centrifugal pump, and then the Whale diaphragm pump, to the discharge point?
I can see that that would work, but if you got in a real pickle, I can't see that it would pump out as much water as two separate systems. But you could have sized it such that it didn't matter.

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A long time ago (7 years) I posted here a similar question.

I proposed to put the Rule pump in series with the Whale pump.
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Old 21-06-2014, 18:52   #12
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Re: Installing 2nd Bilge Pump

I too think that series plumbing would reduce the flow of both pumps, especially the centrifugal, for they do not react well to head increases.

But obviously it will in fact work in the sense that either pump will remove water at some rate. If that is good enough for you, then go for it!

Your choice to make separate systems is the correct one IMO.

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Old 22-06-2014, 03:42   #13
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Re: Installing 2nd Bilge Pump

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<snip>

I can see that that would work, but if you got in a real pickle, I can't see that it would pump out as much water as two separate systems. But you could have sized it such that it didn't matter.
OK so now we are going open the can of worms -

My philosophy - Planning the pump system starts with what catastrophe am I going to try to overcome. Planning a system that will overcome a major collision is not practical. When I go to a bigger boat things like watertight compartments a separate riggable high capacity thrash pump system etc. will be considered - I can't tell anyone what they will be comfortable with.

My biggest through hull is about 1 1/2 inches (head discharge) - all the rest are 1 inch.

So the bilge pumping system serves two purposes for me.

- Empty the bilge of "minor" accumulation - I have leaky cockpit lockers - rain ingress - but working to fix it. We've had the engine water pump drain leak when the pump shaft seal failed. Other engine hoses could fail.
- Buying time - I don't expect a complete hose failure but a leak is possible. However (not having done the math) I doubt the Rule will keep up with a 1 1/2 hole. But for a split hose, chafe etc. it does extend my time to solve.

When I added the rule the intention was not to add capacity - It was to add an automatic system because A) I am lazy and B) I'd like a dry bilge when I come to the boat

Also unless I am multi-crewed I don't expect to be wobble pumping. I will be over the side with the bungs trying to plug the hole. There are a ton of strategies for patching below waterline leaks underway but I won't divert here.

Also I coastal sail. My max time from shore is never greater than about 3 hours. I accept there are scenarios where I may lose the boat if I can't slow the leak or beach it. I am confident though that I can get lifted off the boat and let it sink if I had to.

Oh - Final thought - There is a long thread about the loss Rebel Heart going. One thing RH said that I am taking to heart is, "Once the battery and electrical bay starts getting wet, you start losing power."

No sense having a billion GPH pump system if you don't have electricity...

@Jim Cate is exactly right - The accepted practice is to have separate and redundant systems - the dichotomy of that is another hole in the boat albeit above the waterline.
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Old 22-06-2014, 05:43   #14
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Re: Installing 2nd Bilge Pump

The leak from a 1 1/2" through hull will overwhelm the buoyancy of a 24' boat probably 10 times faster than it will a 40' boat. So little boats don't need smaller bilge pumps than bigger ones; probably the opposite.

I think every boat of whatever size should have some kind of crash pump -- a high capacity pump which will give you some chance of finding the leak before the boat sinks. I use a Rule 4000 with a 2" outlet hose for that. For "maintenance", I have a Whale Supersub 1100gph pump.

On a little boat you could do without the maintenance pump, but I would not, personally, go without the crash pump. A really big manual pump (I forgot who makes it) might be ok as a crash pump, but in a crisis I think I might prefer to have an automatic one, especially if single-handed.

My boat came with two separate outlets for bilge pumps -- one for the standard electric pump and one for the manual pump which evacuates both main bilge and engine room bilge. I added two more, for a total of four, which is the total number of bilge pumps I have. Cutting a hole in the transom is not all that big a deal.

Sinking is no fun, and bilge pumps are like a number of things, like EPIRBS -- they sit and do nothing for years, but when you need them, you REALLY need them.


On my (long) list of things to do on the boat is a fifth bilge pump, or rather portable dewatering pump -- an AC powered very high capacity Honda trash pump, with a folding fire department style hose. Keep in mind that in a severe case of flooding, bilge pumps usually get clogged with trash when the bilge level gets up to levels where water isn't usually found. Be sure you can get to yours so you can clear it; and keeping your bilges spotlessly clean and free of any kind of debris is also a very good idea. A powerful trash pump which simply sucks up and discharges floating debris is a really good idea for a dewatering pump. A portable one can be used to save someone else's boat, too. Which reminds me that I need to move this up the list of priorities.
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Old 22-06-2014, 06:05   #15
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Re: Installing 2nd Bilge Pump

This may help the OP
Understanding Bilge Pumps - YouTube
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