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uncas
07-04-2006, 05:23 PM
Okay, here is the problem:
My thruhull for the bilg is right on the boot stripe. No, I am not going to put another hole in Uncas intentionally. I have a loop in the line going to the bilge pump however, on starboard tack, my bilge pump siphons water back into the bilge and consequently pumps almost continously.
Two options: a check vale on the line, or some insert to put in the loop to prevent back flow. ( there is a name for the second item just being old, it's a blank. )
Any suggestions as to which way to go.

brad9798
07-04-2006, 05:34 PM
One-way valve is the way to go ... just like the chlorinator in my parent's pool that I fixed today ...

John B
07-04-2006, 05:38 PM
ditto Brad.
been there done that. :rolleyes: except it was in the counter and submerged when the hull wave was up there.

Lew Barrett
07-04-2006, 07:02 PM
Another option is a clamshell cowling, but that won't work if the hole is continuously under water, in which case the flapper valve is the solution. The clamshell will do an effective job of keeping out bow wake though, and is foolproof. As it sounds like you will go with the valve, it will take checking from time to time.
Lew

kc8pql
07-04-2006, 07:16 PM
I prefer a vented loop. Check valves restrict flow and can stick open.

Carlsboats
07-04-2006, 07:56 PM
I wouldn't trust any rig unless it included a positive
cutoff valve in the line. You could leave it open most
of the time, but come the day you are slugging along
with that side underwater, it's reassuring to be able
to close it and forget it. Course, you have to remember
to reopen again too.

JimConlin
07-04-2006, 08:15 PM
I think that the textbook solution is to loop the line up to where it couldn't possibly be below WL and put a vented loop in it. The most common failure mode for vented loops if to fail open, meaning that they spritz seawater or worse into some locker. An alternative to the fussy vented-loop valves is a small gauge hose to a cockpit scupper. Either one will break the siphon.

Hwyl
07-04-2006, 08:19 PM
I use a vented loop. Considering that you have a Hinckley, you probably have one in there that's stopped working.

Looks like this

http://shop.sailnet.com/images/forespar/ventedloop.jpg


Next winter you'll need to put a new vented loop in there only higher. What you can do for now is clear out the insides from the vent valve ,they're sometimes made of bicycle tire valve parts (maked "cap" on the picture) so it becomed a pipe with a hole in it, and attach (securely) a thin piece of clear pipe (like they use for windsheild washers), then lead that really high in the boat.
In theory some bilge water can weep from this thin pipe, but I ain't never seen it happen, I always lead it as though it might though.

That'll stop the pump siphoning and the pump can still save your bacon (sorry).

Hwyl
07-04-2006, 08:21 PM
Just read my own post, where the picture says "must be ten inches above the water line" remember it's heeled water line with waves and I'd say 10" is a mighty skinny margin. I'd go for much more in the reinstallation.

Jay Greer
07-04-2006, 10:13 PM
It is called a "sea cock". Open when pumping close when not pumping.
JG

Mrleft8
07-05-2006, 05:27 AM
You could always just jam a piece of bacon in the thru hull when you tack... ;)

Hwyl
07-05-2006, 05:34 AM
You could always just jam a piece of bacon in the thru hull when you tack... ;)

Is that Starboard or Pork.

michaelpetrozzi
07-05-2006, 05:38 AM
Some of those in-line backflow preventers you get from the boat place are very flimsy. I tried one and it came apart where the little screws held the two bits and rubber flap together. Before it came apart i couldn't figure out why the pump was pumping but watre wasn't shifting from the bilger. This was because water was coming out next to the rubber flap in the valve and back into the bilge. The thing worked well for about a week.

Sea cock on the line sounds like the go.

Ian McColgin
07-05-2006, 06:03 AM
I'm sure Jamie has a seacock. But one would not close it and expect the pump to work well when the float switch goes up a bit.

I favor the vented loop and like Lee's idea (who sculled out with his wife in the tiniest dink in the world just to view Uncas) of putting the loop about amidships, under the bridge deck.

Vented loops can fail with age with the diaphram under the pinhole gets stuck in place, but it's an easy fix if it happens and much rarer than a failing check valve, which can jam open with a bit of grit that got past the strum box.

And Jamie, if I don't see you this morning, I'm off the the Vineyard, probably Holms Hole. I'll call.

Dan McCosh
07-05-2006, 06:35 AM
Been using a check valve for about 20 years, and it's never failed. We have a deep bilge, and while back siphoning isn't an issue, the long run of hose to the outlet is. It's almost enough to trigger the pump when it falls back into the bilge. The check valve is at the pump. One problem, however, is that it is possible to have the water column prevent the centrifugal pump from getting a prime if it sucks air. Groco makes a bronze check valve that is very reliable. We also have a siphon break, as the pump runs through the main cockpit scupper outlet.

uncas
07-05-2006, 02:45 PM
Thanks for the suggestions.
Will try the check valve as a temp and then, as sugtggested, next winter, put in a vented loop.