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Old 03-12-2010, 15:09   #1
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In-the-Water Ball Valve Replacement

My new-to-me old boat, on my first sail across the Sea of Cortez, she began filling the bilge about the 3rd day out of San Carlos enroute to La Paz. The bilge pump hummed but didn't reduce the water in the bilge. I located an emergency bilge pump in the next bilge section and pumped into a bucket a dozen or more times and tossed overboard at anchor. At the suggestion of my crewman, an old sailing buddy and architect and builder, I reattached the main bilge pump to the long hose used by the emergency electric pump, and the main pump worked like a champ and had much more head, so we could pump it into the cockpit drains instead of a bucket a few feet higher than the pump.

Ok, so my bilge pump works like a champ, so either the hose is clogged or one of the 10 or so valves on the bilge exhaust plumbing is closed, right?

Anyway, I decided today was bilge pump day. Tried tracing all the hoses once before so had an idea of where they ran but still didn't have the schema straight. One electric pump, another unattached emergency electric pump, one whale gusher and one wall-mounted manual pump.

My new slip neighbors pulled in day before yesterday, a S. African Seattle dweller, Brian, sailing a 50' steelie he built, his second, and his crew, Arn. Brian offers help and I gratefully took it. We (he mostly) figured out how the manual pumps were plumbed and we disconnected the hose from the electric pump and pumped into a bucket. So fine, the pump is good, the hose isn't clogged, so that left the ball valve. The handle moved normally but with screwdriver into the hole a few inches below waterline on the outside, we found it was frozen shut. Great, I'll have to haul to replace. Naw, says sage old Brian, there's ways to do it. Pull the mast over, or place a plug in the thru-hull on the outside. Off to the chandlery I go, bought a packet of various sized plugs and we began taking apart the plumbing. Got it done in about 3 hours, diagnosis to fix. There is still backflow through the bilge pump from the hoses when it shuts off, so we figure I need a check valve or flapper downstream from the pump. Brian says they are common so that's on the list.

Cruisers really are very generous folk. Barely know this guy and he was my plumber and teacher in a valuable project. I look forward to knowing enough to pay it forward.
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Old 03-12-2010, 15:42   #2
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... There is still backflow through the bilge pump from the hoses when it shuts off, so we figure I need a check valve or flapper downstream from the pump. Brian says they are common so that's on the list.

Cruisers really are very generous folk. Barely know this guy and he was my plumber and teacher in a valuable project. I look forward to knowing enough to pay it forward.
Indeed, good (but not uncommon) story.

Many, including I, do not recommend check valves in bilge pump discharge lines. They often fail.

Check valves are prohibited by the American Boat & Yacht Council for use as an anti-siphon device-and with good reason: They're notorious for failing in both the open and the closed position, which respectively leads to flooding or failure to pump.

Check valves may be used, though, to prevent water from a long hose from flowing back to the bilge. However, be warned: If the valve is close to the pump, the pump may not be able to overcome the weight of the water on the other side of the valve, rendering the pump ineffective.
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Old 03-12-2010, 15:49   #3
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So Gord, what will stop the bilge pump from continually cycling if left on auto when one needs to be away from the boat for a week or two? Pumps out, shuts off, back fill, turns on, pumps out, shuts off, back fill .....
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Old 03-12-2010, 16:35   #4
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Say hello to L Paz for me. Love that place. Here is a link to the best bilge system that I have seen. It involves two pumps a larger and a smaller one. The large is set to kick on only when the water gets to a certain height. The smaller one takes care of the "maintenance water" I myself put a brass union on my bilge pump hose so that I could easily take care of any problems that I had with my check valve. I'm sure it is against the boating rules but I have a much drier bilge now.

Installing a Bilge Pump by Don Casey
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Old 03-12-2010, 16:38   #5
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So Gord, what will stop the bilge pump from continually cycling if left on auto when one needs to be away from the boat for a week or two? Pumps out, shuts off, back fill, turns on, pumps out, shuts off, back fill .....
he went on to say they may be used. All good information and your cycling point is a good example seen that. I wouldn't put a check valve in until I had tried balancing the pump and switch locations with pipe size etc... Hopefully the sump is big enough to accommodate a little run back.
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Old 03-12-2010, 17:00   #6
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So Gord, what will stop the bilge pump from continually cycling if left on auto when one needs to be away from the boat for a week or two? Pumps out, shuts off, back fill, turns on, pumps out, shuts off, back fill .....
Maybe place the float switch higher in the bilge so that a full backflow won't set it off?
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Old 04-12-2010, 00:33   #7
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I would use a vented loop setup in that case
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Old 04-12-2010, 05:37   #8
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Indeed, good (but not uncommon) story.

Many, including I, do not recommend check valves in bilge pump discharge lines. They often fail.

Check valves are prohibited by the American Boat & Yacht Council for use as an anti-siphon device-and with good reason: They're notorious for failing in both the open and the closed position, which respectively leads to flooding or failure to pump.

Check valves may be used, though, to prevent water from a long hose from flowing back to the bilge. However, be warned: If the valve is close to the pump, the pump may not be able to overcome the weight of the water on the other side of the valve, rendering the pump ineffective.
Just me, but check valves are a piece of equipment, and as such require maintenance, inspections and replacement. Maintained properly, they rarely fail. The U.S. Navy has one at every (discharge line) through hull opening on every ship in the fleet for good reason. They are very cheap insurance to stop uncheck flow into any vessel should a bilge line fail.

That said, I would NEVER rely on a check valve alone and I would position it as close to the isolation valve as possible. Any line taking suction from, or discharging to the sea should have a means of isolation (seacock). Additionally, the isolation valve must be positioned to isolate the check valve. As with the check valve the isolation valve should be inspected and operated at least monthly, and personally I’d cycle each isolation valve prior to setting sail.

There are several different types of check valves, lift check, stop check and swing check, to name a few. Each of these valves is used for different applications and must be installed properly.

If your pump is unable to generate enough pressure to overcome the column of water sitting on a closed check valve, the system isn't designed properly and you won't be pumping much water with or without the check valve in place.
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