Bilge Pump

Discussion in 'Powerboats' started by estan, Oct 13, 2010.

  1. estan
    Joined: Oct 2010
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    Location: Venezuela

    estan New Member

    Need to install a bilge pump on my powerboat, but distance from the pump to the outlet thru hull is about 5 feet and there is allways water coming back into the bilge . How can I fix this?
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Install a check valve in the outlet hose.

    [​IMG]

    Like this one.
     
  3. estan
    Joined: Oct 2010
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    Location: Venezuela

    estan New Member

    Thanks for you reply......Great idea. I'll look for a check valve like this one.

    Once again Thanks a lot!!!
     
  4. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    Estan,

    Normally I wouldn't argue with Par, but I have had a lot of problems with check-valves, and would highly recommend against them particularly for a bilge pump. The proper way to run a bilge pump is to have the pipe enter at the through hull, lift at least 6 inches vertically, though more is better (up to about 2 foot), then chase down to the pump. This prevents backflow from the throughhull and while the height will decrease pump efficiency to some degree it isn't enough to justify check-valves, that have a long history of clogging open from almost anything.
     
  5. jehardiman
    Joined: Aug 2004
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    jehardiman Senior Member

    Stumble, I think you missed the point. I believe that Estan is complaining about the water in the discharge pipe below the vented loop that flows back through the centrifugal pump when shut off occurs. In bilges that are flat or slack, this can be a problem, also for small deep bilge sumps. I have seen an instalation where the amount of flow back was sufficient to keep the pump short cycling in a seaway. To combat this a check valve is installed, and yes, they need to be constantly maintained. The real question is wether it is placed before or after the pump. In shipboard applications, the check valve is on the suction side to keep the pump (which is most likely above the bilge line) primed. With a submerged bilge pump it can be placed in the discharge line immediately after the pump.


    Estan, I think you should check to see if the pump already has one (many submersible bilge pumps do) and is it working correctly.
     
  6. estan
    Joined: Oct 2010
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    estan New Member

    Hello Guys: You are correct jehardiman! It is a sumerged pump and the situation is exactly as you pointed out. The real problem is the water that flows back to the bilge from the discharge pipe, mantains the bilge wet, creating mildew that even clogs the pump!!!. What about using a regular water pump likr JABSCO ParMAX with an automatic switch conected to it. Would it work?
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    [​IMG]
    This is a rebuild kit for your pump. The best thing you can do is disassemble the pump, clean it up and replace any worn out pieces. I'm fairly sure this pump doesn't have a check valve internally. Inspecting and cleaning out check valves should be done annually at least, more often if you boat has active leaks and the pump cycles regularly. Crap and debris can collect inside the pump and the check valve, holding the valve open and clogging up the pump. Routine maintenance is the only true method of keeping up with these sort of things. I mention this because Stumble is correct and those of us that deal with a marine life daily, see lots of check valve problems that can lead to huge other problems. Again this is a routine maintenance issue not a part problem.
     

  8. Stumble
    Joined: Oct 2008
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    Location: New Orleans

    Stumble Senior Member

    I love when I answer the wrong question. :(

    Estan,

    What I have done is used a conventional bilge pump rig without a checkvalve. However I added a small diaphram pump with the pick up in the bottom of the sump on a timer that runs for 90 seconds after the vane pump turn off. This pump leaves so little water in the bilge that short of going after it with paper towels there isn't anything there.

    It does backflow a small amount, but probably less than a quart of water spread over the size of the bilge is as close to completely dry as I could imagine without adding seperate sumps just to hold the little bit of residual bilge water. Again though I would point out that for me check valves always seem to go bad, and after replacing them over and over again I just choose not to use them, your experience may vary.
     
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