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Old 09-10-2018, 04:11 PM   #1
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Aft bilge pump advice

We had the unpleasant experience of our aft bilge high water alarm going off recently. When I checked the aft lazarette there was a moderate amount of water present. I started the generator, that acts as an emergency bilge pump, and used a hand pump as well to remove the water. It became clear that the water was entering via the aft bilge pump. The issue is that while the discharge is above the water line at rest or at low speeds, when we are planing the thru hulls for our aft bilge pump and fish box macerater are submerged. The hose from the bilge pump thru hull to the pump is a direct fall. The bilge pump and its check valve had failed, allowing water to drain into the sump and lazerette. We replaced the faulty pump, with its associated check valve ( comes with the pump), but we still have water draining down into the sump and cycling the pump. I attached some photos and would love suggestions on how to prevent this from occurring in the future. The repair will involve removing the cockpit floor - which is straight forward as it is designed to be removed easily - for access.
Thanks in advance for any ideas
Eric
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Old 09-10-2018, 04:25 PM   #2
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Hard to tell from the pix how this would work on your boat, but the best practice is to have the hose loop above the through hull to above where the waterline is "at the greatest point of heel". Some throw an anti siphon at the top of the loop too, which to me makes sense only if you can't get the loop high enough. On my old Hatteras we had a bunch of through hulls almost right at the level waterline, and never had an issue due to the height of the loops, and no anti-siphons or check valves either. I really don't like introducing a check valve in a bilge pump system, too much crud can cause them to fail.
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Old 09-10-2018, 04:26 PM   #3
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First get rid of the cheap corrugated hose. When it fails it usually breaks in half. Use a reinforced marine water hose.

Second, you need to add a "vented loop" at the highest point you can. This will prevent water siphoning back into the bilge.
Third, get rid of the check valve. Nothing but trouble in the bilge pump application.
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Old 09-10-2018, 05:57 PM   #4
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We will definitely replace all of the hoses while we have access.
I thought the loop makes the most sense as well, with removal of the check valve
Thanks for the advice

Eric
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Old 09-11-2018, 06:29 AM   #5
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If there is room an anti siphon loop in the line from the pump to the discharge should be installed.

They can be had in plastic or bronze , and are no restriction as a check valve usually is.
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