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  #1   IP: 4.229.144.134
Old 08-22-2009, 10:39 AM
Steve Lomas Steve Lomas is offline
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Sinking Feeling

I've joined up here to try to solve a mystery flooding problem-

I've owned a '79 Catalina 30 for 4 years- everything seems well maintained and works great, except...

Once or twice a season, I am motoring along happily - I go below and discover water is splashing out the rear hatch from the engine compartment-
water is up to the level of the bilge covers- the carpet is soaked-
and I'm trying to remember where I put the inflatable kayak.

The interesting/worrying thing is that this happens quite rapidly- once less than an hour after I'd last checked the bilge.

It's not the thru-hull valve for the head, it stays closed.
I can't see any evidence of leaking from any hoses or the water pump- and the bilge is normally dry other than a little rain water that seeps in from somewhere.

Any ideas much appreciated!

Steve
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  #2   IP: 68.104.51.117
Old 08-22-2009, 11:20 AM
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roadnsky roadnsky is offline
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Does it ONLY happen when you are motoring?
If so, have you looked around the engine (while it's running) for leaking?
Although, a leak of that volume would likely effect your engine performance I would think.

You mentioned the thru-hull for the head.
What about the raw water intake thru-hull for the engine?
Other thru-hulls?
Does your bilge pump out a thru-hull or thru-transom?

Check all thru-hull and thru-transom fitting AND their hoses.
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  #3   IP: 4.229.144.134
Old 08-22-2009, 12:05 PM
Steve Lomas Steve Lomas is offline
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Yes, at least I've only discovered it while motoring- because of the rotating shaft-coupling splashing up water, but I always check the bilge before starting the engine after sailing-

-I haven't thought to check the engine itself for leaking- but by the time the water is this high- everything is soaked so it's hard to tell. Normally no sign of any leaks into the bilge from anywhere though- tightened all the hose clamps on thru-hull fittings- not the transom ones though- I'll check those.

I agree that you'd expect some other problem if the cooling system leaked this badly- overheating?- but temp is normal- exhaust flow is normal- I have a loud clicking exhaust valve that would be very noticable if it stopped.

I hadn't thought of the bilge pump-I think it's thru-hull- You know when I think of it- this may actually happen soon after using the electric bilge pump- I press the button for a couple of seconds sometimes to hear if its pumping any water-

Do you think it's possible that the pump is allowing a back-flow
of water from outside?
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  #4   IP: 64.203.32.52
Old 08-22-2009, 12:25 PM
Dave Neptune Dave Neptune is offline
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Question Syphon

Steve, if your B/pump exits below the water line it is indeed possible to start a back flow. The exit for the water being removed should be above the W/L or have a vacuum break installed (A POOR SET UP) and if there is a V/break it may be sticking.

How fast is the water getting in? You mentioned that the bilge stays fairly dry then something drastic must be happening to allow so much so fast.

Also check the exit of the pump while underway as it may be above the water line sitting still however it may be under while moving due to the quarter wave moving "up" the transom.

FYI, on my boat when motoring hard a little water is forced up the rudder-post and runs into the bilge. It isn't much but food for thought.

Stay dry

Dave Neptune
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  #5   IP: 72.89.246.49
Old 08-22-2009, 12:32 PM
tenders tenders is offline
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Is your shaft seal or stuffing box leaking?
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  #6   IP: 4.229.144.134
Old 08-22-2009, 01:22 PM
Steve Lomas Steve Lomas is offline
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I really don't know where the bilge water exits, my attention was on the engine before- but it might explain the intermittent nature, and the fairly rapid leak- I know the bilge flooded completely in 30-45 mins one time. Also the only conditions I can remember were fairly calm- which would support the idea of the quarter wave putting it under the water line...

OK so I have a new leading theory now (well actually Dave's theory), when I run the pump, a little water in the hose always runs back into the bilge- which proves water can flow backwards through it. Normally this just sucks in air behind it, but with a steady wave covering the outlet- it acts as a siphon and maintains a back flow of water?

Seems like this should be a common known problem /design flaw though if it's true.- but I'll see if I can reproduce it- and find/check the outlet underway
(sounds like a job for one of my more agile nephews!)

Thanks much for the help

Last edited by Steve Lomas; 08-22-2009 at 01:46 PM.
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  #7   IP: 151.196.56.145
Old 08-22-2009, 01:25 PM
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msauntry msauntry is offline
 
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I boat I've been on for years has had a problem where they are slowly sinking each time they motor, but are otherwise dry. Finally found out it was the shaft seal that at a particular RPM would allow a tremendous amount of water in. Rev a little higher or lower and you wouldn't see it, but at this certain RPM there must have been an occilation that breaks the seal and gushes water in. This was not a regular stuffing box, but one of the dripless shaft seals.

Recommned you have someone motor around at different rpms while you watch the engine.
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  #8   IP: 4.229.144.134
Old 08-22-2009, 01:25 PM
Steve Lomas Steve Lomas is offline
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Quote:
Originally Posted by tenders View Post
Is your shaft seal or stuffing box leaking?
Hey let's not get personal! No - I should have mentioned that at first- just the normal slow drip while running!

Last edited by Steve Lomas; 08-22-2009 at 02:04 PM.
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  #9   IP: 173.73.53.19
Old 08-23-2009, 07:02 PM
keelcooler keelcooler is offline
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I think Dave may have it. Motoring tends to pull down the stern bringing the rudder tube top near water level. Hull wave tends to peak near the cockpit also.

Fill the tanks,load up the folks and you are down in the stern. Most sail boats do not have a proper stuffing box at the rudder tube top only a splash collar.Most rudder tubes extend 5 to 6 in above water line. Some tiller models extend to the cockpit sole.

Next time your loaded and motoring, check your rudder gland collar.
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Old 08-24-2009, 04:31 AM
rheaton rheaton is offline
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I had a similiar problem with my 78 Catalina 30 once. Turned out to be a loose connection in my sink drain plumbing. I learned that it is not good to leave your thur-hull drain seacock open, while motoring, when your drain plumbing is not secure.

Best of luck.
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Old 08-24-2009, 10:11 AM
Steve Lomas Steve Lomas is offline
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Thanks- I'll check all the suggestions here- rudder post, sink drain, bilge pump and shaft seal at different rpm.- and follow up if I can identify which one's to blame-

Always pays to keep an open mind- the first time it happened I convinced myself it was melted ice in the ice box suddenly draining into the bilge until it happened again.
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  #12   IP: 206.125.176.3
Old 08-24-2009, 11:31 AM
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sastanley sastanley is offline
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Steve - I have a '77 Catalina 30. The boat did not have a bilge pump when new, and according to the PO, a local yard installed one. They put the exit under the transom, in about the same location as the cockpit scuppers. You can get to these from inside the boat by removing the small square access 'hatch' (mine is the ugly 1970's fake wood veneer stuff) all the way at the back of the quarterberth on centerline. You will also see the exhaust thru-hull & rudder tube here. The PO warned me about pumping the bilge underway and the associated siphon problem..At rest it is about 6" above the waterline, but even motoring along at 4.5 knots the boat creates enough sternwave to completely cover the pump thru-hull. On my list of things to do to fix this problem is a tall loop somewhere in the middle of the boat.

I would agree that a bilge pump siphon is the most likely scenario given the volume of water you are seeing.

Other ideas, specific to a C-30:
When working on my new-to-me boat this winter, I found that the exhaust thru-hull (coming out the transom) had a crack it, which I am sure contributed to water in the boat when the engine was running.

I would also check the scuppers and their hoses..again, at rest, they are above the waterline, but when moving the stern wave will submerse them. A leaky or bad hose here could allow water in.

A leak in the exhaust system..maybe the muffler (the PO had the OEM stainless one fail after about 5 years, a plastic Vetus has worked great for the last 25), or a leaky hose connection in the exhaust or the hose itself may be failing. My exhaust hose had the metal wire 'springing' out of it from rust. I suspect the inside layer of hose was compromised from age and had gotten to the wire.

That should give you a good list to start with - Follow up and we'll keep at it until we have solved it.
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