Repacking stern gland.

[supermalc]

Taking my own advice (for a change <grin>) I've done a search through the forum. Loads of posts, but I was told I need 'graphite impregnated string', and I can find no mention of the type to use.

Someone has just mentioned graphite is top of the galvanic tree, and it can cause severe corrosion of the prop, and shaft.

A very experienced seaman and boat builder has sent me some of this 'string', so I expect it will be the correct product.

My boat will be mainly on a river, so fresh water.

He has also explained how I need to repack it i.e. cut pieces to go around the shaft, leaving a small gap.

The gland is the type with a large nut, and the shaft is approx 1".

Although it looks a straight forward job, any advice will be appreciated, as it will be the first time I have done this.

<hr width=100% size=1>Malcolm.
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[tome]

Malcolm

I assume the boat will be out of the water?

The trickiest part of the procedure is getting the old stuff out. You need to fashion a small tool such as the tang of an old file bent at right angles and sharpened to grab the old packing. It obviously has to fit the space between the shaft and the gland housing (log). Be careful not to score the shaft or housing.

Once you have the old stuff out, carefully cut the new packing to fit the shaft. Best to do it slightly oversize and then take thin slices off using a sharp knife until the length is correct . Once you've done this, cut the rest to the same length. Fit it using some grease, and with each successive join at 90 degrees to the last. Wind the nut back on, whilst rotating the shaft so that you don't over-tighten. Turn the greaser until you see grease emerge around the shaft and check that the shaft is still free - you may have to back the nut off a little.

It isn't difficult, but it is a little fiddly.

Good luck
Tom

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[Bodach na mara]

The stuff is hardly "string" but is a square section material impregnated with graphite grease. When I did mine on a boat with a 1" shaft, I had to dig out some of the old stuff and measure the section. It was 1/4" square (yes, old imperial units). I acquired somehow about 12" of new packing and cut three new bits to fill the gland. I was not told to "leave a small gap" but to cut the ends at 45 degrees to fit the packing exactly round the shaft. It seemed to work anyway.

<hr width=100% size=1>Ken Johnson

 

[supermalc]

I was thinking of doing it in the water. It can wait of course. I need to put it on the trailer sometime to measure, and then change the prop. The water level is raised in April, and the slipway is on the lower level. Just have to wait until my friend is available with his tractor and trailer.

Will the water pressure make it difficult to repack the new string? I can of course just undo the nut and add one fresh ring.

Also will the quantity of water be a flood. There is an auto bilge pump, but will this be overcome.

Another person at the mooring has just done his with the boat in the water. As he also had not done one before. I suspect he just wrapped the string around the shaft. He said he was disappointed a day or two later, as it had started leaking again. I was intending to tell him how to do it.

Mine was leaking rather badly, until I remembered to put some grease in the greaser and grease the shaft. There is a large quantity of grease through the front of the nut.

If the gland is properly packed, and unless the shaft is badly worn, I would have thought you would only see a few drips if you forgot to re-grease before leaving the boat.

<hr width=100% size=1>Malcolm.
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[Joe]

Dont use Graphite impregnated gland packing!!
It will rot your stern gear.
Go to you good local chandlers and get some non graphite impregnated packing using a bit of the old stuff to get the right size.
When you cut each piece cut the ends at about 45 degrees opposite each other so that each end slightly overlaps the other once joined.
Then fit each ones join at 90 degrees to the last.
Joe


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[Guest]

My thoughts !!

a) The packing should be white and waxy to the feel - not the black-grey graphite style
b) Grease oozing from the front nut is normal and shows that you have forced it in ...
c) a few drips evry now and then is ok as completely stopping the drips by overtightening will damage the shaft ..... pumping grease before leaving boat to stop the drips is fine.
d) as above - overtightening the gland will actually damage the shaft and make the wholesituation much worse and difficult to seal
e) the packing often is 3 rings cut to fit the shaft with a miniscule gap where ends nearly meet. The joints should be staggered around the shaft so as not to align and provide a water passage. Rmember that when you pump grease in it needs a passage to go, and also that when the gland nut is tightened - the gaps in the packing ends will close up.

OK ?


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif<P ID="edit"><FONT SIZE=-1>Edited by nigel_luther on 03/03/2004 18:46 (server time).</FONT></P>

 

[rich]

Re: My thoughts !!

Nigel,Do you need Teflon grease with the white stuff?

<hr width=100% size=1><A target="_blank" HREF=http://www.jersey-harbours.com>http://www.jersey-harbours.com</A>

 

[Guest]

Re: My thoughts !!

?? I just use standard marine grade grease - never even thought about it !!!

I am not an engineer - just bought another pot of what was on boat before !!!


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif

 

[Superflid]

Never done one on a boat, but the pumps "dahn t'pit" were a similar setup.

A long wood screw brazed onto a length of rod with a short "T" handle brazed on the other end makes removal of the old stuff easy.

We always staggered the joints at 180 degrees to the last one, cutting at 45 degrees.

Wouldn't have thought that there would be a tidal wave hit you when it came out, could it be slowed from outside by wrapping some rag around the shaft? (unless you need scuba gear to get to it!). Possibly best advice will come from experienced boaters.

<hr width=100% size=1>

 

[supermalc]

Thanks for your replies....and also thanks to the net. I have now a good idea of how to do it, and what to expect BEFORE starting the job. Usually you only know afterwards, when you have been swamped with problems, and probably swamped the boat as well.

<hr width=100% size=1>Malcolm.
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[2_rollocks]

Re: My thoughts !!

I've always used Duckhams Keenol. It's nice and squishy ie not too thick and waterproof. Re-packed my stern gland 2 years ago and have yet to retighten it.

<hr width=100% size=1>

 

[andyball]

rather than a chandlers, try a local engineers suppliers or somewhere that might sell/repair big valves.

chandlers, 450mm : up to £5 (& none of them had the size I wanted) . JW Tout (local eng.supplies) £3.50+vat for 2 meters

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[supermalc]

Re: My thoughts !!

Thanks Nigel - your post is exactly what I need, should also be useful for others who may be doing this for the first time.

One question remains. As graphite has been used for years (I've been told about this) and ptfe is somewhat new, and yes I can understand why it will be better. how come the shaft appears to be years old, in fact it looks original, and I am assuming the packing is graphite impregnated.

Before I got it the boat was in salt water....for how long, and how much use is totally unknown.

Of course I am assuming all of this, making 'an intelligent guess'. When I have done the job, or removed the nut and seen what is in the gland, I will of course be better informed.

<hr width=100% size=1>Malcolm.
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[Jools_of_Top_Cat]

Re: My thoughts !!

I did mine on the water, once the first piece is in place any inflow of the tide will be stopped, so it is the last out and the first in that require planning. The inflow was not too bad, a little nervy at first but as I was prepared it went without glitch.

You can pre cut the first two or three packs and have them ready to insert pretty much as soon as you remove the last old piece.

It is much less water than say extracting your log paddle wheel.

This is only what I did, if you are uncomfortable don't do it, I do not want the guilt of you writing on here that some idiot said it would be ok and you almost sunk your boat /forums/images/icons/frown.gif

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk>Top Cat Homepage</A>

 

[supermalc]

Re: My thoughts !!

Thanks Julian - don't worry, I won't.

<hr width=100% size=1>Malcolm.
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[roger]

Teflon impregnated packing

When I last had to do this I bought teflon impregnated packing - square in section. I didnt find it easy to get the right size and although warned not to by the instructions I had to hammer the packing a bit to make it fit.
I now use a carbon thrust race type seal bought in Dunkirk for about £90 which works very well and needs no attention.
I dont know about you but I find work on the stern gland one of the nastiest jobs on the boat. Access is difficult and you have to stand on your head

<hr width=100% size=1>Roger

 

[Joe]

Re: My thoughts !!

Dont leave a small gap between the ends of each piece of packing unless you want it to start leaking.
Cut the ends of each piece at about 45degrees to each other so that they overlap slightly.
When compressed the ends because they are at 45 degrees will slide over each other (if you got the sizing right) forming a water tight seal.
Joe

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[dulcibella]

If you have any difficulty loosening the nut, try repetitive tapping of the end of the flat with a very small hammer - usually works witin a few minutes.

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[Guest]

No argument - please read

Funny isn't it ....... one man says this - another says this ...

Having spent cadet time on ships packing deck valves subjected to all the seas etc. with expensive cargoes under ..... we packed by the method I gave. The miniscule gap is closed by the gland nut compressing and spreading the packing. I certainly did not intend to give the impression that the gap should be more than a fag-paper width when not compressed !!! The use of a 45 deg. cut makes sense and I can only agree that it may be better - I never say my way is perfect - its just the way I was taught .....


<hr width=100% size=1>Nigel ...
<A target="_blank" HREF=http://www.qqbaltic.com/index.html>http://www.qqbaltic.com/index.html</A> For all those disbelievers ! /forums/images/icons/cool.gif

 

[supermalc]

I've been down to the boat today, but did not get time to look at the gland yet....however because of the need to wash the bilges, I did take the top off the sea cock and open it. The water flow was quite calm, and it took quite a while to get enough water to open the float switch. So I've definately no qualms about taking the stern gland nut off with the boat in the water.

Like everything else though, I suppose I'll have to do it twice, as I've been sent graphited string, and need to know the correct size before I buy some ptfe.

I also took the new anode, however when I took the one off the engine, it is still like new, so I've a spare. Doubt I'll ever need it.

I'll keep you all informed of my progress of course, and thanks again for all the valuable info.

<hr width=100% size=1>Malcolm.
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