Unidentified leak in Southerly 105

[Cardo]

Unidentified leak in Southerly 105 - Identified! What now? See post #39

Over the last few weeks we seem to have developed a salt water leak that I simply can't find the source of. As far as I can tell, it's getting worse, but all the digging through the bilges and checking over the engine does not seem to be shedding any light.

The leak is a slow'ish one, though the auto bilge pump did run yesterday evening, again at 4am and again when we got up at 9ish today. That's the most often it's run so far. It's only a small pump with a short range on the float switch, so it can set off without too much water coming in. However, I would estimate (a very, very rough estimate) there's at least a good 5 to 10 litres being pumped out each time.

I did initially think the problem was a leaking hot water tank (which does have a very minor leak when under pressure, but the water tank level would be dropping a lot quicker. I've also tasted the water, and as far as I can tell this is salt water (it's a little hard to tell as we also had a hydraulic leak which has left some fluid residue in the bilges). I did turn off the fresh water pump and left the hot water tap open last night, but as mentioned the water level still seems to have risen somewhat overnight.

I've checked over all the seacocks, and they seem fine.
I've checked the keel bolts, and as far as I can tell they don't seem to be leaking.
I've checked the various pipes from the seacocks, again no signs of leaks.
I've checked over the engine. No leaks from the water inlet or the exhaust that I can find. I've also checked the tell tale and that seems fine.

It hasn't rained in the last couple of weeks, so it's not rain water getting in.

I'm very much running out of ideas, and I fear wherever this leak is coming from it may well be getting worse. Judging by the quantity of water that is being pumped out, the leak should be reasonably obvious to spot, but it is so far completely eluding me.

Any thoughts or suggestions would be very much appreciated.

 

[Talulah]

Is there a holding tank on board?
Bowthruster?

 

[Cardo]

Is there a holding tank on board?
Bowthruster?

Have both, both are fine. Holding tank was empty overnight, and the bow thruster has its own little bilge area. I have checked them both anyway, and seem fine.

I've also checked the shaft gland, and that looks fine.

 

[Talulah]

Rudder stocks?

 

[Cardo]

Rudder stocks?

Transom hung rudders. I've checked the mounts and they seem fine. This area drains into a different part of the bilge, which is fine.

 

[dancrane]

Maybe it's possible to segment the bilge area into sections, using mastic & offcuts of ply or plastic, enabling inspection hour by hour to establish the whereabouts of the leak?

Has the drop-keel had a knock in recent weeks?

 

[sarabande]

That must be quite a worry.


Have you got this Southerly manual ?

http://arcarius.org.uk/stats/S110Manual.pdf

It checks various possibilities.


This link suggests bolts to the anodes being eaten away.
http://www.sailnet.com/forums/buying-boat-articles/28346-southerly-101-a.html


If it is salt water, then it must be a hull fitting, and all you can do is check each one against your owner's diagrams for integrity.

Can you block off the limber holes ahead and abaft the main bilge ? That might tell you whether the leak is from for'd or aft, for starters.


Best of luck.

 

[Twister_Ken]

Is it possible to dry the bilge, then line it with sheets of old newspaper? Watch carefully and see which sheet gets wet first.

 

[Mandarin331]

Surround the water in the bilge with talcum powder (on a dry surface), this will show clearly what direction the water is coming from, then using the same technique you should be able to track it back to its origin. Probably best to use unperfumed unless you like the scent If you have any suspicions about a hull fitting you can do the same there.

 

[BruceDanforth]

Is it coming in at rest or when sailing?

Have you had a look at your ultra dependable watermaker?

 

[Colvic Watson]

Some helpful advice I've had -

1. Put talc down in suspect areas
2. It may seem like salt water but a freshwater leak will pick up salt in the bilges - we had a fresh water leak and blamed it on a stern gland for ages
3. Is the stern gland definitely OK? A small regular drip will add up to a lot overnight

 

[Downsman]

" there's at least a good 5 to 10 litres being pumped out each time."

That's more than a trickle and obviously worrying if the volume coming aboard seems to be increasing. Perhaps it's time to think of a lift-out? Once out, dry the hull totally then fill the bilge with a fresh water hose. Leave it overnight and you may get lucky and detect a leak/weep from a hull fitting/gland that you've missed when looking from inside the boat, if you look closely from outside. Sounds a desperate measure but if you have tried everything else, might be worth a punt.

 

[Just_sayin']

I think that you're making it difficult for yourself by having pollution in the bilges. If you can't tell whether the water is fresh or salt you really don't know where to start.

So, pump lots and lots of fresh water and detergent into the bilges. Flush, and repeat until you're just putting in fresh that then tastes fresh.

Dry out and then monitor as above.

Ask me how I know to do that :ambivalence:

 

[Cloven]

May be a long shot but our boat neighbour has the same boat as yours and last year it developed a leak. Turns out it was a failed push-fit connector in the fresh water system and the joint in question was in the heads area which if I remember correctly is on starboard side at the foot of the companionway steps. Connector in question was on the aft bulkhead at about head height.

Hope this helps

 

[TQA]

Another vote for the talcum powder trick.

The trails will lead you to the leak.

 

[Cardo]

Thanks all for the advice.
I will try to get the bilges dry, though it really isn't easy. It's a relatively flat, wide bilge, so getting the water out of the bottom couple of cm is nigh on impossible. But I'll get the hand held bilge pump on it and see what I can do.
Then I shall spread some talcum powder and make a right mess!

 

[Mistroma]

One other possibility is the cutless bearing. On the S95, the bearing is inside a bronze fitting that's pushed in from outside and held with 2 bolts. The bolts are down in a hollow section underneath and behind the prop. gland. I once had a slight leak from this area on my old S95. It would fill the hollow section and then eventually run forward into the flat centre bilge.

I think that this is a remote possibility but worth checking if S105 is same as S95 (pretty certain it will be).

 

[Cardo]

One other possibility is the cutless bearing. On the S95, the bearing is inside a bronze fitting that's pushed in from outside and held with 2 bolts. The bolts are down in a hollow section underneath and behind the prop. gland. I once had a slight leak from this area on my old S95. It would fill the hollow section and then eventually run forward into the flat centre bilge.

I think that this is a remote possibility but worth checking if S105 is same as S95 (pretty certain it will be).

I'm pretty certain the gland and that part of the boat are not involved as they have "basins" which would be filling with water before they drained into the other parts of the bilge. So far, these hollows have remained dry.

I'm starting to wonder whether the leak may be from the fresh water system. I can't locate it, but this was my original thought, and if the water could taste salty due to bilge dirt and remaining salt, that would explain the taste. I really can't find any external sources of water. Ideally, I'd like to empty out the water tanks and see what happens overnight, but we need the water to drink at the moment! I'll close of the tanks and see what happens tonight, though. Worth a shot, I guess!

 

[AntarcticPilot]

You can test for salt using a solution of silver nitrate, which a chemist might be able to supply. If you add the water suspected of being salt to a solution of silver nitrate, if salt is present, it will cause a curdy white precipitate that will turn dark on exposure to light. It's the standard lab test for chlorides. Try it with a sample of sea-water first, to get an idea of the amount of precipitate you're expecting, and then with bilge-water - that will give you an idea of whether it's straight sea-water or whether it has been diluted with fresh water.

PS; I've just doscovered you can buy Silver Nitrate from Amazon!

 

[BruceDanforth]

Alternatively taste the bilge water and then taste the sea.

You can test for salt using a solution of silver nitrate, which a chemist might be able to supply. If you add the water suspected of being salt to a solution of silver nitrate, if salt is present, it will cause a curdy white precipitate that will turn dark on exposure to light. It's the standard lab test for chlorides. Try it with a sample of sea-water first, to get an idea of the amount of precipitate you're expecting, and then with bilge-water - that will give you an idea of whether it's straight sea-water or whether it has been diluted with fresh water.