I am not sure if this will help - I had bilge water in my bilge and for a while I was not able to find its source. By luck I found that the rudder post cover was leaking and letting in water into the bilge. I removed the cover and washed it with fresh water and lubricated the rubber ring and applied white pipe thread paste to the female thread and re-installed the cover. There is not water in the bilge any longer. I also tasted the salty water and it appears that it was coming in from the sea - but it was only because of the rain and when we rinsed the boat.

2 separate problems, or maybe not depending.

Water ingress could be any of the prop shaft packing (likely), keel bolts weeping (less likely), rudder shaft packing (less likely), or...

Bilge pump return comes from not having a siphon break in the bilge pump outlet line. I added one of these about 5' from the pump and now only get about 5' worth of siphon returning to the bilge.

Now, without a siphon break, you certainly CAN get water filling the bilge through the bilge pump system under sail, at certain angles of heel and load (specifically, if the bilge pump outlet is under water).

So it could be just the siphon break, which you need to fix anyways. Then you will be able to tell if there is a further problem. If you have traditional prop shaft packing I would check that, with the engine engaged in fwd and with the revs up over 1500, to see how much dripping or trickling (or spraying!) you are experiencing.

Siphon break is not the same as a check valve, although a properly installed one of those will accomplish roughly the same thing. The Siphon break is an inverted U in the piping, above the waterline, with an air check valve pointing upwards, which allows air back into the line when siphon pressure is applied and makes the water run downhill from the U in both directions rather than all the water in the hose running to the lowest point (inside the boat).

The advantage is that it can't get stuck open or closed like a check valve and does not restrict the flow like a check valve.

[QUOTE=Nimue;15637]

The advantage is that it can't get stuck open or closed like a check valve and does not restrict the flow like a check valve.[/QUOTE]

Jason, a vented loop does need to be serviced. Salt can gum up the little flapper valve inside. You're correct about the no flow restriction.

Stu,

You are correct, but the point is that even a 'stuck' siphon break will not impede the function of the bilge pump, where a stuck check valve most certainly can.

I have my siphon break installed outboard of the dinette in the aft seatback pocket. I have also seen a number of C36's with the siphon break installed under the galley counter next to the sink. I think this is probably the better location as it will remain above waterline even when heeled.

Ed,
This talks about adding a second bilge pump, but the principles apply to the first bilge pump, too.
[url]http://www.c36ia.com/node/944[/url]

I believe that most experts would advise against a check valve in a bilge pump hose, while an anti-siphon loop (siphon break) is universally recommended for bilge pumps.

Hi Tom,

Q: With no check valve in the bilge pump hose, doesn't that mean all the water uphill of the bilge pump (the entire hose length) will come back down into the bilge after turning off the bilge pump?

.

[QUOTE=RPowers;15669]
Q: With no check valve in the bilge pump hose, doesn't that mean all the water uphill of the bilge pump (the entire hose length) will come back down into the bilge after turning off the bilge pump?
.[/QUOTE]
Yes, it does. But -- at least as I understand it from reading the advice of those with more expertise than I -- the choice is between the harm (if any) done by a little water remaining in the bilge vs. the risk of a sunken boat from a stuck check valve. I'd go with the former.

We always have some water in the bilge, probably from the prop shaft drips and rainwater seepage down the mast, so I'm somewhat amazed at those who report here that they are able to maintain dusty dry bilges. But I copied Soko's 2-pump design with the siphon break mounted inside the galley sink cabinet (thanks, Tom!), and as a result the length of hose "uphill of the bilge pump" from which water will drain back into the bilge is now only about 4'. And since this a small diameter hose (for the smaller of the 2 pumps), its a rather minimal amount of water.

Rick,
Exactly what Matt said. IF the large pump is working, it means you have a LOT of water in the bilge, and backflow is the least of your problems. The smaller pump takes care of 99% of the water that finds its way into the bilge, and with a very short, small diameter hose between the pump and the siphon break, the backflow is maybe a cup. Every once in a while I turn off the small pump and test the large one. When it turns off, the backflow amount is significant. I then turn the small pump back on, and it takes most of the water out. When it turns off, the backflow is tiny, and the water left in the bilge not a problem. Hope this helps.

.

Aha, I understand.

I have a big pump with large diameter tubing and one check-valve just off the pump.

What kind of pump do you use for the small one, and could you detail where it's smaller hose goes?

I like the idea of the sink area. Could the smaller pump exhaust into the sink drain?

.

Again, Rick, take a look at the pictures of Tom's installation ([url]www.c36ia.com/node/944[/url]). That should make it fairly clear. We as well used a 500 gpm pump, reducing the output down to a 1/2" hose between the pump and the siphon break, and than ran a 3/4" hose (snaked alongside the existing bilge hose) out to its own dedicated through-hull in the stern.

I imagine in theory one could route the output to the kitchen sink, as you suggest, but that would mean that you would ALWAYS have to leave the seacock open, right? We're pretty disciplined about closing ALL the seacocks anytime we're going to be off the boat for any length of time - even an afternoon. A burst hose or failed hose clamp could leave your boat at the bottom of the harbor fairly quick.

The one thing I need to change this winter is to move the 2nd pump aft to the same compartment in the bilge as the larger pump. Turns out the second pump is too close to the fluxgate compass and throws the auto-pilot off somewhat. (Not a big job)

Areas you may not have checked would be your exhaust line and heat exchanger, and water pump. These are located to the rear and front of the engine and from your notes you may have checked them. The other place to look would be your macerator lines and your galley sink thru hull and hose clamps. All of these would allow salt water to enter and if you are certain it is not coming from the rear of the vessel, then the macerator or sink thru hull drain may be the culprits. I have a year 2000 Catalina 36 and I found fresh water system leaks which required a going over and tightening of all hose clamps and going to brass fittings on the hot water heater instead of the plastic. In fact it is a good idea to go over all hose clamps. I was surprised at how loose some were. The bilge water return after the bilge pump runs is not a big deal as any changes to that simple system may come back to haunt you. I would suggest drying everything out and have a good sailing buddy go below and open all access to engine, floor board access, and pulling the bottom drawer to expose the galley drain as well as pulling the cushions above the macerator. Then just observe as you take her through a normal sailing activity. The inflow will show itself and then you can take corrective action.

Could also be water from the sink in the head if on stbd tack...