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Water in bilge


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Whenever we take our boat out we end up with sea water in the bilge. When we leave her berthed, the bilge is bone dry, even if it rains. The previous owner used her heaps and said he always had a dry bilge. So what might have happened?

 

For example, we Motored to Motuihe and back again the other day due to lack of wind, about 4.5 hours, and had about a mug and a half full of seawater in bilge. We are sure it comes from the stern, but where exactly? How can we check? We filmed the stern gland for about 15 minutes running and couldn't see any dripping - although it was as interesting as watching paint drying, so maybe we blinked at the wrong time...

 

Today we Sailed to Motuhie and back again and took the same time. The bilge was bone dry to start, but at the end we were surprised to see alot more salt water than just motoring - about a fifth of a bucket full. I've read on the internet that you can get water through the stanchions, but we don't get rain water in via that route so what could be causing a leak during sailing?

 

Note, the mast is deck stepped and our hull/boat is an early 80's GRP model.

 

I wouldn't mind so much a bit of water, but the keel washers are going rusty - can see the rust marks through the 2 pot epoxy painted in bilge and I don't want it to spread. Luckily the keel bolts are 'clean' and shiney - we saw this as a bit of paint chipped off the top of one of them.

 

As before, appreciate any ideas, experiences you can throw out there! Cheers.

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What sort of shaft seal do you have?

Sounds like it's a conventional stuffing box. Needs a pump of grease after you've been motoring. If it needs a pump regularly, I.e. There is water in the bilge every time you've motored somewhere, then probably needs the stuffing re stuffed.

 

There is a thread recently about it. The stuffing is like a hemp / flax rope, coiled into the stuffing box and pumped full of axle grease. If you have poor shaft alignment or vibration while motoring it can also let more water in while motoring (vibration making a gap while the shaft spins). If you know what you are doing, apparently you can do it on the water. I'd recommend drying out to do it. Shouldn't take too long, maybe 30min job, it's just a major pain getting down to where the stuffing box is generally.

 

We have a grease gun fitted to the stuffing box so we can give it a quick pump (one or two strokes) when we get back to the mooring. Rotating shaft pushes the grease back creating an annulus for sea water to drip in. Quick pump when back on the mooring closes the annulus again.

 

If it s not the stuffing box, I'd think you are stuffed... It may be a welsh onion onboard.

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I've had similar problems before.... One was a rain water leak down the outside of the top rudder bearing, the water gathered in an aft locker but didn't "appear" in the bilge until the boat heeled while sailing. The other was a leaking fitting on one of the water bladders that only leaked on one tack.

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Yeah, we are going to look at stuffing box when we take her out onto the hard after summer.

 

However could the salt water be coming from this area if we only sailed the whole day and only used the motor to get in and out of the marina? There was heaps more salt water in bilge on the day of sailing versus the day of motoring...the water is definitely salty and not fresh - the taste test!

 

We've had a wet exhaust pipe split a couple of weeks ago, I smelt the burning rubber before we even got out of the marina! It's another story, but we have always opened the seacock before starting engine - raw engine cooling Bukh 10dv, so don't know why it happened. After fixing hose tested waterflow and was getting 2 lites in 45 seconds, put a new impeller in and then got 2 litres in 30 seconds - water quite hot to feel and grey (that is clear with black partcles) after running engine for 5 minutes in gear while berthed, but hoping and assuming its ok now!

 

I'm hoping its not the welsh onion!

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Hi Prawn, What is the Boat? Someone with the same may have had this problem and found the answer. I have heard of this question several times in the past.
Most things have been covered I think, apart from rudder shaft. Some shaft tubes exit below water line when underway, due to bum sitting down a little more in the water and due to some water forced up shaft tube. Also, is there a skin fitting that exits above waterline when stationary.
Exhaust is something to double check if you have had previous problems. I would check the clamps around things like the Water lift box and silencer if you have one, goosneck and through hull. It only takes the slightest of dribble to add up to a significant amount accumulate over some time.
So did the camera pick up water suddenly entering the bilge area when the boat came to a stand still? If you didn't have the camera set up for that, perhaps set it up for a larger view and see of you can see if the water comes from a particular direction. You could do similar by placing some towels in areas and see which one gets damp while others remain dry.

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If the stuffing box is dry (as in no grease), it can come in while sailing, but will also come in while on your berth, with all the seacocks closed. You'll get most volume when you first arrive at the boat. 

If its only coming in when your seacocks are open, i.e. not dependent on sailing or motoring, then I would go looking for a welsh onion on a system attached to a seacock. if you've recently had issues and done work on the raw water system, that would be a target rich place to start looking.

From a risk point of view, a stuffing box wont fail catastrophically, i.e. let go and let water pour in. They just fail slowly. A loose hoseclip or any other worn or failing component in a system off a seacock can fail catastrophically.

 

The other day we found a very small weep on a metal elbow off the sink drain seacock. Went to tighten it and the elbow collapsed in a pile of corroded muck... now has a nice plastic one. That very minor incident could have been a cluster if we didn't find it when we did, all fittings are now plastic :-)

 

PS, leaks / leeks are clearly bad luck on a boat, so its best never to mention them by name.

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newspapers in the bilge also good as they change colour when wet

And fall apart potentially blocking bilge pumps/switches.

 

Is it salt or fresh water? Fresh would indicate a leak into a locker or similar as per the suggestion above.

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My bet would be on the exhaust if you've recently had to do work there. However , also check around your whole raw water cooling and any salt water plumbing, I had one over christmas that was a bit elusive, eventually found it in a syphon break.

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Adding to what everyone else is saying, I would also consider the possibility that you have multiple causes (one motoring and one sailing).  As a random thought do you turn off the ingress and egress thru hull fitting taps for the toilet when you are sailing?  In some boats the toilet bowl is lower than the waterline and you can get a siphon effect that lets water in (I am assuming you have a standard salt water toilet here).  There should be a loop that is higher than the max waterline and a siphon valve but at high heel angles the loop can still be lower than the waterline and let water in.  Some older boats don't have a siphon valve fitted that makes this worse.

 

Just a thought ....

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As another thought from someone who solved this quiz - Keel bolts.  

 

When the boat is sitting on it's mooring it doesn't have much side to side movement however once you're under way there is significant pressure.

 

I theorized correctly that there was just enough movement that squeezed water through once sailing, leaning over and bumping through waves.  She'd take on about 1/2 cup after a weekend but sitting on the mooring would be dry until going out again.

 

I dropped the keel, cleaned up the bottom of the boat, re-seated, re-faired, replaced the keel bolts and dry boat thereafter.

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And a thought on stuffing boxes that leak even when sailing.  When you're motoring there's constant pressure up the shaft minimizing waggle movement, when sailing, the shaft is more likely to get some effort on the prop buffeting it and causing more waggling.  Once back in the marina there's still enough 'stuffing' to stop the seepage when there's no movement.

 

And someone earlier mentioned the rudder - if it's an internal tube and the stuffing has gone - absolutely this is the culprit. 

 

There's a word.  I'm trying to think of.  It describes a form of pumping.  Canti.... canta... anyone?  driving me more insane right now.  

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Capillary ?

Not sure if that is the right phenomena though, the type of water ingress is likely to be due to differential pressure.

Capillary was what I was looking for - thank you :thumbup:   I was thinking about water ingress into a small cavity which is then squeezed up/out.  This was what was happening with my keel.  

I lifted up the floor boards when sailing, got right down in the bilges and watched.  As the boat went over/through a wave I didn't see any physical movement of the bolt, however there was this tiny seepage around the bolt head.  After a couple of hours sailing the dry bilge had water that I sponged out and then they stayed dry until she was sailed again.  Much less if I motored.

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Great, thanks everyone for your ideas and suggestions.

 

Think you're right, different leak sailing vs motoring.

 

Motoring it comes from stern - we've set up a small collection receptable (ie tube and plastic jar) which was full when we motored.

 

And when we sailed we suspect the seawater is coming from the bow area as our stern jar was empty and I pressed a clean paper towels on the sides around bilge afterwards and it was dry. Yikes, I hope its not from the keel bolts which appear to have no movement.

 

We recently greased the stuffing box...too much maybe?

We have a transom hung rudder, so no shaft.

We usually go out with all the seacocks closed except the engine one (obviously) and the galley sink one. I did open the toilette holding tank outlet that day, usually for for about a minute, but that day a sailing friend said to do it for longer - so 5 minutes...don't know if that would do anything.

 

The other day sailing was quite 'choppy' for our little boat under 8 metres. Water was washing over the bow etc particularly when we hit a ferry wake etc.

 

Will recheck the raw water cooling system and all the saltwater plumbing. Now thinking of taking the floor home so we can watch whats happening next time we're out. Will check all the throughputs when we lift her out hopefully after summer...hopefully we can wait that long.

 

Will keep you posted when we find it. Hopefully it won't take as long as a motor boating friend, who took 4 years to find his leak!

 

'Six months in a leaky boat'...

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From my experience, check all around your engine raw water pump. The back of them where there drive shaft exits through the seal can be real sneaky for leaks.

This can account for water ingress when either motoring or sailing. As a quick check, try a decent sail with the engine raw water inlet skin fitting valve closed and see how you go.

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