Re: Discharge of Bilge [N]

From: Eric Johnson (etj@nwlink.com)
Date: Sun Mar 12 2000 - 23:11:16 PST


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>Greeting all:
>One more point on bilge pumps. Given the shallow bilge depth of the Potters;

FWIW I was able to modify a Rule 500 pump to fit IN the skeg itself, in the
stern, under the winch and cockpit drain.

>putting the bilge pump outlet high and far away from the pump will cause the

>water in the line to backflow into the bilge when the pump can't extract any

>more and loses suction. this could set up a cycle where the pump empties
>the bilge, shuts off (or loses suction) and then turns itself back on as the

>gallon or so in the lines refloods the bilge.

I used a rule switch that has some unique properties in that it doesn't switch
ON until the switch has floated pretty high, but doesn't switch OFF until its
pretty low, so I'm not too worried about it cycling too much. it would take
a tremendous amount of water in the lines to make the switch raise the inch
or so it needs to turn on again after it has shut down. YMMV with other switches,
but i suspect most are designed the same way.

>An in-line check valve would
>prevent this.

Don Casey recommends against using a check valve because of the likelihood of
clogging. I'm still not sure whether I'll add one (or a scupper flap at the
output).

I've got everything hooked up now (electricity and mounting) except i still
haven't drilled the drain hole. I think I'm going to put it up pretty high.
http://www.nwlink.com



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