stern Tube Leaking

[Glennbrown]

The dam things leaking badly !!!

 

See below (thanks carlt )

Edited July 11, 2008 by Glennbrown

[carlt]

Do you need new packing?

 

 

Ignore me, now I've looked at the photo.

Edited July 11, 2008 by carlt

[Glennbrown]

Sorry all trying to upload a bloody picture without success

 

The stern tube is leaking where it screws into the welded steel collar

It wont tighten any more and is pooring in !!

 

Any suggestions please!

Edited July 11, 2008 by Glennbrown

[magnetman]

isn't there normally some kind of cross brace stopping the whole assembly from rotating with the shaft?? Looks a bit odd to me.

 

 

It should have been screwed in with ptfe tape on the threads maybe it wasn't done right

[carlt]

Sorry all trying to upload a bloody picture without success

 

The stern tube is leaking where it screws into the welded steel collar

It wont tighten any more and is pooring in !!

 

Any suggestions please!

It looks like a lot of unsupported tube. Is the installation correct?

[Glennbrown]

There is

 

The picture was taken whilst being built -prior to the greaser plate being welded in-sorry!

[John Orentas]

The stern tube is leaking where it screws into the welded steel collar

It wont tighten any more and is pooring in !!

 

Any suggestions please!

 

 

Hi Glenn.

 

The problem will be easily cured by the use a thread sealer, I would recommend PTFE tape, plenty of it.. You do of course need another support strut for the stern tube to pick up on the two holes that can be seen, so the tube has to be taken off again anyway.

[Glennbrown]

Thanks John -the stern tube is supported

 

How the heck do you undue the stern tube in the water with out sinking !!!!!!

[Bullfrog]

Look here when we had something similar - but nowhere near "pouring" in:-

 

http://www.canalworld.net/forums/index.php...ost&p=67520

[alan_fincher]

 

isn't there normally some kind of cross brace stopping the whole assembly from rotating with the shaft?? Looks a bit odd to me.

 

It should have been screwed in with ptfe tape on the threads maybe it wasn't done right

Yes, I agree with MagnetMan.

 

The installation looks completely weird.

 

There is nothing supporting the front end of the stern tube.

 

That part with two bolt holes through it, immediately behind where the feed from the plastic greaser pipe goes in, should be attached to a part of the hull you don't have.

 

Also I agree it's my understanding that there should be PTFE tape sealing that leaking joint. But with the other end of the stern tube unsupported, I would have thought the joint was subject to so much vibration that anything could have happened.

 

You may need a docking to resolve this, I fear, although liberal applications of a sealent like Fernox LS-X (I think!) can sometimes stem things for a bit.

 

 

EDIT:

 

OK, scrub all that! I now see it's a part built picture, not the final result!

Edited July 11, 2008 by alan_fincher

[Timleech]

There is

 

The picture was taken whilst being built -prior to the greaser plate being welded in-sorry!

 

Is the boat still 'new'? If so, get the builder to sort it out!

 

Fixing it will entail unbolting the stuffing box from the support plate, unscrewing the tube from the stern post, reassembling with some sealing material on the threads (PTFE isn't ideal but it does have the benefit that it doesn't set and interfere with future dismantling), and making sure that the threads on the tube are screwed up tight. Achieving this might entail cutting the support plate free from the hull, as it may be too far forward and thus interfere with the tightening. It will almost certainly involve drilling for new bolt holes, as the chances are the 'tight' position won't be as 'pretty' as the present one. It also is a bit tricky to do unless the boat is out of the water, but some greasy rag wrapped around the shaft just behind the sternpost may help if you can't avoid doing it 'wet'.

This is not an unusual problem, often because the builder is more concerned with a neat result than a sound one.

 

Tim

Edited July 11, 2008 by Timleech

[Glennbrown]

Alan

 

The stern tube/greaser has a support plate bolted with 2 nuts and bolts not as in theis picture

'

 

The installation is correct -sorry for the confusing picture !!1

[RobinJ]

There is

 

The picture was taken whilst being built -prior to the greaser plate being welded in-sorry!

What you need to do is disconnect the shaft (flange on the front of the Centraflex) and the bolts holding the packing gland onto the cross brace and ensure the whole tube is screwed up tight.

It is unusual for a large leak from the stern tube thread, so make sure it is not leaking from the welds around the rear bearing or swim.

There is a possibility that some movement at the engine end has put strain on the thread, so checking above with it disconnected will show whether it is still aligned.

If it is indeed leaking through the thread and is not misaligned, you may be able to slide the tube forward far enough to seal the thread, but you are likely to get a quantity of water coming in while you do it. It will be easier if you also undo the stuffing flange to release any pressure on the shaft and make it slide easier.

You may have to consider drying it out to look at properly!

[John Orentas]

Thanks John -the stern tube is supported

 

How the heck do you undue the stern tube in the water with out sinking !!!!!!

 

 

Well, basically you can't, though in theory it may be possible to Partially unscrew the tube and treat with said PTFE tape on the threads that can be accessed.. But to repeat, don't screw the thing all the way out as yo may not get it re-started..

 

This is not such a desperate situation as you might imagine, if you are left with a leak, it will in time cure itself with the oxidising of the steel welded in flange.

 

Of course some-one else may have a better idea !

[magnetman]

Well, basically you can't, though in theory it may be possible to Partially unscrew the tube and treat with said PTFE tape on the threads that can be accessed.. But to repeat, don't screw the thing all the way out as yo may not get it re-started..

 

This is not such a desperate situation as you might imagine, if you are left with a leak, it will in time cure itself with the oxidising of the steel welded in flange.

 

Of course some-one else may have a better idea !

 

if you got a massive tarpaulin you could put it right round the boat to keep it afloat if you needed to get the tube right out without letting in the whole of the surrounding canal. might be cheaper than a dry dock? and more fun...

[alan_fincher]

Alan

 

The stern tube/greaser has a support plate bolted with 2 nuts and bolts not as in theis picture

'

 

The installation is correct -sorry for the confusing picture !!1

Yes, understood.

 

Non-the-less the whole arrangement looks remarkably short compared to any other I have seen. Something like 9 to 12 inches of stern tube showing is I believe far more normal than the three of 4 inches your's seems to have.

 

To me, that means a much shorter distance between the bearing at the "canal" end and the packing gland on the inside. I'm guessing this could result in greater forces on the threads holding it all together.

 

Has the leak just developed out of nowhere, or are you aware of the prop impacting anything hard, that might have help disturb things, please ?

 

Alan

[Glennbrown]

Jesus Magnetman !!-you sound a lot braver than me !!!!!!!!

 

Alan

 

The leak has been getting worse for some time but now is starting to worry me

 

The boat is booked into Worsley dry dock in September but thats 20 miles away and when the boat

 

is under steam the leak is all the way around this joint -bit worried about the jouney!

 

Might try this weeking to get at the prop shaft thru weed hacth ,seal with insulation tape and see if I can undo Strern tube to get some ptfe tape round the threads

 

but there is not much room !!!

 

And your right does seem very short

Edited July 11, 2008 by Glennbrown

[BlueStringPudding]

if you got a massive tarpaulin you could put it right round the boat to keep it afloat if you needed to get the tube right out without letting in the whole of the surrounding canal. might be cheaper than a dry dock? and more fun...

 

 

Rrrrrrriiiiip! Splosh. Glug.

[alan_fincher]

if you are left with a leak, it will in time cure itself with the oxidising of the steel welded in flange.

I wish this was always true, John.

 

When ours did this, it got progressively worse, not better.

 

I was able to effect a temporary repair by binding a load of plumber's hemp around it, impregnated with the Fernox Leak Sealer (think it's called LSX), but needed several attempts before I stemmed it.

 

It was then fine to leave until the boat needed a regular docking.

 

(Shame the engineer repacked the gland with wrong size packing, to give me a leak to replace the one he had fixed..... )

[RobinJ]

Well, basically you can't, though in theory it may be possible to Partially unscrew the tube and treat with said PTFE tape on the threads that can be accessed.. But to repeat, don't screw the thing all the way out as yo may not get it re-started..

 

This is not such a desperate situation as you might imagine, if you are left with a leak, it will in time cure itself with the oxidising of the steel welded in flange.

 

Of course some-one else may have a better idea !

In theory (and this is supposed to be a relatively new installation) there should not be a large gap between the rear bearing or bush and the shaft, so the amount of water coming in shouldn't be enormous.

It is a couple of years ago when I did this to mine (and I made sure I was in shallow water just in case), I hardly got any water in at all (in fact I seemed to get less than I had before I took it apart).

Just make sure you have a good bilge pump!

[blackrose]

How odd?

 

Without wishing to start the whole debate again, it was only a couple of weeks ago that many here were adamant that leaks of this kind could not occur with greasy stern glands and that only water lubricated glands could suffer from such problems...

[John Orentas]

Just make sure you have a good bilge pump!

 

 

Robin,

 

I think you have got the wrong end of the stick, it is not water coming 'through' the stern tube that is the problem, we are talking about screwing the whole thing out of the hull.

[denboy]

get a large heavey duty plastic bag and go through the weed hatch and place the bag over the prop and secure it with a bungee chord tightly to the round bit that sticks out from the boat a couple of inches(technical term)you can then take the whole thing off from inside with only a bit of water comming in board ie only whats in the bag the water pressure will push the bag in to seal any leaks (if any )while you reseal the tube

[alan_fincher]

How odd?

 

Without wishing to start the whole debate again, it was only a couple of weeks ago that many here were adamant that leaks of this kind could not occur with greasy stern glands and that only water lubricated glands could suffer from such problems...

Reread those previous threads....

 

It was stated that you couldn't get a catastrophic failure in a conventional stern gear.

 

Nothing catastrophic has happened here, nor is it likely to.

 

(Unless the boss is not correctly welded to the hull, which would not be a stern gear fault, it would be a boat-builder fault. )

Edited July 11, 2008 by alan_fincher

[RobinJ]

I think you have got the wrong end of the stick, it is not water coming 'through' the stern tube that is the problem, we are talking about screwing the whole thing out of the hull.

I thought we were talking about unscrewing the stern tube from the rear housing, not removing the housing, which on mine is bolted on from the outside!