Bilge Pumps and back flow - SailNet Community
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post #1 of 3 Old 05-29-2009 Thread Starter
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Bilge Pumps and back flow

So I tear the Rule 2000 out and the hose before the refit. I flicked the switch and it ran for a few further thought.

18 months later and I'm putting the pump back in, all cleaned up and tested in a bucket. Looks great. Dump some water in the bilge and the thing starts cranking. Really moves water..until the float shuts off, then the sizable hose full of water flows back to the bilge. Just enough for the pump to turn on, fill the hose then shut off, over and over.

What am I missing? No check valve, would rather not have one. I can't put a high point in the hose any nearer the pump.


Preserved Killick

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post #2 of 3 Old 05-29-2009
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It sounds like you have hit a one-in-a-million combination where the volume of water in the hose, combined with the contour of your bilge, and the hysterisis of the float switch, are exactly right to make the returning water trip the float switch again and again.

Relocating the hose, raising the float switch (the pump, if that's integral) or changing the volume that the bilge holds by the float switch all would work. The may leave more water in the bilge or a less desirable hose run, but you'll have to pick the compromise. The alternative is to use one large pump as a "flooding" pump, and locate that an inch or two higher than your "drain pump" which is a small pump with a small hose, designed just to get the last half inch of water out.

Since bilge pumps seem to burn out frequently anyway, having a dual setup may be less wasteful than you think.
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post #3 of 3 Old 05-29-2009
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What HS is suggesting is the typical installation I usually recommend. Two pumps. The first is a maintenance pump and is smaller capacity, with a smaller hose, and has the float switch in the very bottom of the bilge. The second is a larger dewatering pump and has its float switch an inch or two higher.


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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
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