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  #1  
Old 01-29-2009
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Urgent Issue: Bilge/Anti-Siphon

So last night our bilge pump started going on every thirty seconds. We looked and there was a continuous stream of salt water entering our bilge. We spent 3 hours ripping apart our boat and it mysteriously stopped.

This morning it started again, and we pulled apart the boat and this is what we found. The bilge pump goes to a 5' hose, then to a check valve, then to a loop well above water level, then back down below waterline to a non-closable through-hull. On the top of the loop there is a 1/4" hose that leads right back to our bilge, below waterline. The water is coming through the vent hose that leads back to our bilge.

I'm assuming that at some point there was a standard air vent on the top of the vented loop. Perhaps when the boat was heeling and the rail was in the water, the vent spurted water, so someone put a hose on it to drain it to the bilge. It looks like our check-valve needs replacing too. At this point, it looks like we're creating a siphon at random times as opposed to breaking it.

Based on what you've read here, what are your thoughts on the proper way to have the bilge line hooked up? We're still taking water in and need to replace it ASAP.
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  #2  
Old 01-29-2009
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Catalina uses a very similar system. As the original system was designed, it sounds like the right system to me. Obviously, you want to replace the check valve and fix the loop if it has been gerry rigged They are renound for getting stopped up and failing - especially after a rough ride when things start breaking lookse or running free in the bilge. However, they are useful and most of the larger Catalinas put them on. It is of interest to note that many higher-end builders do not.

I would say fix what you have right now. Carry a spare check-valve. Do you also have a highwater alarm? You could rig it fairly easily into your system and add another bilge pump into that so that it adds another level of safety. We will not go back to sea without one.

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  #3  
Old 01-29-2009
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If the bilge pump exits via a below-the-waterline through-hull, it needs a seacock on it. If that hose ruptures, you're basically RTF... That would be the first thing I'd recommend doing. Replacing the siphon break would be the second. Don't use a check valve, they're just a RPITA and can cause some serious problems in a bilge pump output line.
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Old 01-29-2009
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Something similar happened to us a few years ago. It is initially disconcerting while you try to locate the source of the water.

I agree, there should be a seacock on that thru-hull. Ours is nominally above the waterline (just), and it has a true seacock on it. So we were able to simply open/close it manually until we fixed the ant-siphon vent.

What happens is that when you load up a boat for cruising, that thru-hull can easily end-up below the waterline, which makes it more vulnerable to back-siphon if there's a problem with the siphon break.

I don't know about the hose contraption leading back to the bilge, but I don't think it's the ultimate source of the problem.

Clean/repair or simply replace the anti-siphon loop. They can get crusted up with salt residue. Right now it is sticking, and causing that vent line to create a siphon back to the bilge.
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Old 01-29-2009
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I respectfully dissagree with Dog on that one. I respect what he say, but I dissagree here. I believe a checkvalve is a good system, but requires maintenance and requirs you to carry a replace. Generally you can clean/repair these yourself. Don't give up on theis one yet. At the bery least, you might be able to use it as a spare.

Catalina does not put a valve on the output of the bilge either. I guess the point is that if you are getting water coming through while on a tack, you would fall off and fix the issues. The siphon break is supposed to handle the backflow - not the check valve. THe check valve is to keep the water between the two to keep from flowing back into the bilge. It serves a good purpose. It could be argued that the check valve is a backup system... though that is not its intention.

By the way, is your siphon break centerline? Where is it on the boat?

Brian
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  #6  
Old 01-29-2009
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I have no knowledge of the Passport 40 but...
Shouldn't that system have a seacock below the waterline?
Provided you have the appropriate sized bungs, replacing (or even repairing depending on where you are moored) the check valve and getting a seacock on that throughhull wouldn't be difficult.

Having a bung or two handy would priority 1 in case that check valve gets stuck full open.

[edit]
Oops, looks like several beat me to the punch. Glad I was on the same wavelength.
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Old 01-29-2009
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I missread his post. I did not realize that the bilge pump exited below the waterline. I agree with Dog on that. Ours exits well above the waterline.

- CD
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  #8  
Old 01-29-2009
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Quote:
Originally Posted by Cruisingdad View Post
I respectfully dissagree with Dog on that one. I respect what he say, but I dissagree here. I believe a checkvalve is a good system, but requires maintenance and requirs you to carry a replace. Generally you can clean/repair these yourself. Don't give up on theis one yet. At the bery least, you might be able to use it as a spare.

THe check valve is to keep the water between the two to keep from flowing back into the bilge. It serves a good purpose. It could be argued that the check valve is a backup system... though that is not its intention.

By the way, is your siphon break centerline? Where is it on the boat?

Brian
I'll also agree that check valves are bad news. Centrifugal pumps have very little ability to overcome head pressure. 15' of 1" hose that goes to a point 6' above the level of the pump will and can often create a cavitating bilge pump that does nothing but make bubbles in the blige because it can't overcome the head pressure of the water in the hose.

Many moons ago, when I worked in boat yards, we yanked check valves all the time. A customer would come in complaining that the pump was running but the bilge would not drain and instead would just kill the battery. 30 seconds later armed with only a screw driver the check valve was gone and the bilge pump working.

If you don't like the drain back then invest the $1.39 on a turkey baster. Check valves are a safety problem and I have seen it more times than I can count. Even in brand new installations I have seen pumps cavitate against the head pressure of the static water stuck in the bilge line...

If you use a high head capacity diaphragm pump go ahead and use a check valve but if you have a centrifugal pump (Rule type) throw it away and get a turkey baster or sponge.

I personally do not like any bilge pump exiting below the static waterline as it's accepted safe practice that all seacocks should be closed when one leaves the boat unattended. closing the bilge pump seacock defeats the purpose of having a bilge pump..?

The ABYC build standard and before that, USCG advice, has been that any below waterline fitting requires a seacock that can be shut. In the most recent iteration of ABYC H-27 they loosened up the the rules around seacocks being installed to max heeled waterline. You no longer need to install a seacock above the static waterline to be ABYC compliant, though it is advised as good practice, but you always need one for below water applications..
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Last edited by Maine Sail; 01-29-2009 at 03:09 PM.
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  #9  
Old 01-29-2009
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OK... let's forget about the seacock - I already know I need to put one in at the next haul. Let's also forget about the check valve. I'm more interested in figuring out what I should do with that vent hose that runs below the waterline to our bilge and is siphoning the water - I need to fix that before anything else. I'm thinking of yanking it off, but then I'm concerned about water getting into the cabinet where the loop is.
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Quote:
Originally Posted by labatt View Post
OK... let's forget about the seacock - I already know I need to put one in at the next haul. Let's also forget about the check valve. I'm more interested in figuring out what I should do with that vent hose that runs below the waterline to our bilge and is siphoning the water - I need to fix that before anything else. I'm thinking of yanking it off, but then I'm concerned about water getting into the cabinet where the loop is.
Labatt,

I guess I did not make it clear above, but the problem is not this line. The problem is with the vented loop ant-siphon valve. It is likely gunked up with crud and is sticking. Take it off, clean it up, and put it back in place as it was. Or replace it with a new one. That should solve the immediate problem and you can worry about a seacock down the road.
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