Bilge pump siphoning while sailing

[Al Smith]

Has anyone else experienced this happening? We were out sailing in 8-18 knot winds, running with following seas about 2 feet high. Our CD 33's ice box drains into the bilge so I began to hand-pump out the water while my wife handled the helm (she does a better job at that than I do). I pumped and pumped and was curious as to how the ice had melted so much. Surprise, the bilge pump hose was siphoning water back into the bilge to a level of 8-10 inches , then pumping irregularly, clearing some of the water and then allowing more to siphon back in. It couldn't keep up with the siphoned water, so I suppose it was just a matter of time before we would have seen water over the cabin sole. Fortunately, I was able to disconnect the hose and plugged it and hand-pumped the bilge dry. Back at the dock, I reconnected the pump and all was fine! I assume that it was a combination of following seas, heel, speed, trim, and possibly the kind of pump itself, since it evidently has no siphon block. Anyway, any comments?

Al



saylr@mindspring.com

[Carl Jones]

Has anyone else experienced this happening? We were out sailing in 8-18 knot winds, running with following seas about 2 feet high. Our CD 33's ice box drains into the bilge so I began to hand-pump out the water while my wife handled the helm (she does a better job at that than I do). I pumped and pumped and was curious as to how the ice had melted so much. Surprise, the bilge pump hose was siphoning water back into the bilge to a level of 8-10 inches , then pumping irregularly, clearing some of the water and then allowing more to siphon back in. It couldn't keep up with the siphoned water, so I suppose it was just a matter of time before we would have seen water over the cabin sole. Fortunately, I was able to disconnect the hose and plugged it and hand-pumped the bilge dry. Back at the dock, I reconnected the pump and all was fine! I assume that it was a combination of following seas, heel, speed, trim, and possibly the kind of pump itself, since it evidently has no siphon block. Anyway, any comments?

Al

That happened to me once while motor sailing down the Intercoastal at hull speed. The bow wave was the exact same length as the boat, and there was a crest even with the transom. She was heeled about 15 degrees, and this combination put the automatic bilge pump discharge under water. The pump kept cycling, which caught my attention. Once I figured out what was causing it, I slowed down enough to let the pump catch up and stop, then put a wooden plug in the discharge to keep the water out. I now keep a plug taped to the stern pulpit for that purpose. The deck just isn't high enough to make a high enough anti-siphon loop for these conditions. You could install a check, but I don't think I would trust one. I think vigilance and common sense is the best solution. I guess these Cape Dorys are just too fast for their own good!!

Good Luck,
Carl Jones
Spanish Eyes CD30



GreatCells@aol.com

[Larry DeMers]

There is a solution here. If the exit is on the side of the boat, route your hose to the boats centerline directly from the thruhull, then bend it towards the bilge, staying as high as you can in the under cockpit area. At the last foot or so of this run, add a vertical bump to the hose, before decending to the bilge.
With this arrangement, the water will have to go up the hose to the ships midline before it could start a syphoning event. If the hose has this suggested rise in it at the end, then any water in the hose will slide back out of the hose when the boat comes off heel. Mainly, the horizontal run from the thruhull to the boats centerline is what keeps the syphoning from happening.

Cheers!

Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~Lake Superior~~

Has anyone else experienced this happening? We were out sailing in 8-18 knot winds, running with following seas about 2 feet high. Our CD 33's ice box drains into the bilge so I began to hand-pump out the water while my wife handled the helm (she does a better job at that than I do). I pumped and pumped and was curious as to how the ice had melted so much. Surprise, the bilge pump hose was siphoning water back into the bilge to a level of 8-10 inches , then pumping irregularly, clearing some of the water and then allowing more to siphon back in. It couldn't keep up with the siphoned water, so I suppose it was just a matter of time before we would have seen water over the cabin sole. Fortunately, I was able to disconnect the hose and plugged it and hand-pumped the bilge dry. Back at the dock, I reconnected the pump and all was fine! I assume that it was a combination of following seas, heel, speed, trim, and possibly the kind of pump itself, since it evidently has no siphon block. Anyway, any comments?

Al

That happened to me once while motor sailing down the Intercoastal at hull speed. The bow wave was the exact same length as the boat, and there was a crest even with the transom. She was heeled about 15 degrees, and this combination put the automatic bilge pump discharge under water. The pump kept cycling, which caught my attention. Once I figured out what was causing it, I slowed down enough to let the pump catch up and stop, then put a wooden plug in the discharge to keep the water out. I now keep a plug taped to the stern pulpit for that purpose. The deck just isn't high enough to make a high enough anti-siphon loop for these conditions. You could install a check, but I don't think I would trust one. I think vigilance and common sense is the best solution. I guess these Cape Dorys are just too fast for their own good!!

Good Luck,
Carl Jones
Spanish Eyes CD30

demers@sgi.com

[Don Carr]

A simple, straightforward solution is to install a check valve outboard of the bilge pump discharge. Forespar is one manufacturer that comes to mind.



carrds@us.ibm.com

[Mike Thorpe]

Al,

I ran into the same problem on my CD-36 Journey's End last summer while returning home from Nantucket. I ended up disconnecting the hose to break the suction. Last winter I moved the the discharge thru hulls for both the automatic & manual bilge pumps from the port quarter to the transom. Problem solved.

Mike
Thorpe

Has anyone else experienced this happening? We were out sailing in 8-18 knot winds, running with following seas about 2 feet high. Our CD 33's ice box drains into the bilge so I began to hand-pump out the water while my wife handled the helm (she does a better job at that than I do). I pumped and pumped and was curious as to how the ice had melted so much. Surprise, the bilge pump hose was siphoning water back into the bilge to a level of 8-10 inches , then pumping irregularly, clearing some of the water and then allowing more to siphon back in. It couldn't keep up with the siphoned water, so I suppose it was just a matter of time before we would have seen water over the cabin sole. Fortunately, I was able to disconnect the hose and plugged it and hand-pumped the bilge dry. Back at the dock, I reconnected the pump and all was fine! I assume that it was a combination of following seas, heel, speed, trim, and possibly the kind of pump itself, since it evidently has no siphon block. Anyway, any comments?

Al

mthorpe@capecod.net