Author Topic: Bilge pump hose route  (Read 5239 times)

bensails

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Bilge pump hose route
« on: June 12, 2017, 01:21:14 PM »
I had to replace my electric bilge pump outlet hose on a P32.  I thought I followed the route carefully, but the water will no longer climb the loop forming a backflow preventer.  I water stops about halfway up the loop and stalls there.  only by taking the loop out could I get the ware to the outlet.

selene

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Re: Bilge pump hose route
« Reply #1 on: June 13, 2017, 01:28:39 PM »
Thinking aloud here, there are a few options you may wish to consider:
- Hose blockage
- Some vented loops include an anti-backflow valve. Not a good idea, IMHO. They can get stuck, preventing outflow.
- Type of hose - a larger diameter, smooth bore (inside) hose is better than a ridged, small diameter hose, especially for longer distances
- Blockage at pump, e.g. strainer
- Bad/damaged pump.

My money is on the last two....

If the water no longer climbs the loop, that implies there is not enough pressure.  I don't know how long the run is on a P32, but clearly you need to be able to get a sufficient GPM output to deal with a leak...so it should be not merely marginal, but gushing out!

Hope this helps...

bensails

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Re: Bilge pump hose route
« Reply #2 on: June 13, 2017, 01:50:21 PM »
Thanks for the thoughts.
It is a new pump, rated higher than the old one, 2200 gph.  New hose, 1"ID, recommended by pump manufacturer. 

selene

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Re: Bilge pump hose route
« Reply #3 on: June 14, 2017, 12:08:51 PM »
Dang. Well, the advice is worth what you paid for it!! :-) Sorry it was not more help.

Okay, well in your shoes I would start with basic tests. This is going to get ugly, I know! Since you have done all the troubleshooting you can in the boat, I would move onto the hard for testing.

So I would put the bilge pump into a water supply - bucket, barrel, swimming pool, etc. - with the bilge hose attached, and see if you get 2200 gph.  Which is a little over 30 gallons a minute! Clearly the pump needs to be submerged; a partially submerged pump will just suck air.

If all works well, you could then lift the pipe and simulate the full run with antisiphon. Lift the pipe up, and see what it does with the flow. A 6' lift can reduce the output by 40%. But that is still ~15 gallons a minute for you, not the trickle you were describing.  This is an old article but still relevant: http://www.boatus.com/magazine/2014/december/bilge-pump-capacity.asp

It it all works out of the boat, then you need to carefully reinstall and test the run in the boat. 

It will be tedious, but proceeding methodically, and making no assumptions is needed.  Probably like me you went straight to the obvious problem areas; but it is rarely that simple. So when that does not work, I am forced to take the methodical component-by-component test route. Sometimes the problem turns out to be where you least expect it - like does the brand-new pump actually pump?  Coincidentally, I had a brand-new unit fail on me.

Good luck




MangoCats

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Re: Bilge pump hose route
« Reply #4 on: February 20, 2019, 12:09:32 PM »
My "high output" bilge pump wasn't getting any water out, I traced that problem to a kinked hose... not sure how likely you are to have a kink you don't know about.