Stern gland stuffing

[lancelot]

Hi.
I have my yacht (Cobra 850) on the hard at the moment. I thought it may be wise to check the stuffing inside the stern gland. How will I know if I need to replace the stuffing material? I don't how long it has been since it has been replaced. I have had the boat about 4/5 years. I turn the greaser every week when it is moored and about once when I am using at sea. I do have some water under the stern gland and only need to drain it after a couple of months or so.
How many turns of stuffing material should be inside?
I have never adjusted the stern gland nuts (one locking and one for adjusting).
Fair winds,
Lancelot

 

[pvb]

If it doesn't particularly leak, leave it alone.

 

[lenseman]

If it doesn't particularly leak, leave it alone.

Of course it doesn't leak, the OP says, "it's on the hard"!

 

[pvb]

Of course it doesn't leak, the OP says, "it's on the hard"!

Ah, yes!

 

[ghostlymoron]

If you can see some threads, you could nip it up a touch to reduce leakage. No point in replacing the packing if there is still some adjustment. There's lots of useful info on Vyv Cox's website http://coxengineering.web.officelive.com/Sternglands.aspx

 

[Caer Urfa]

Hi.
I have my yacht (Cobra 850) on the hard at the moment. I thought it may be wise to check the stuffing inside the stern gland. How will I know if I need to replace the stuffing material? I don't how long it has been since it has been replaced. I have had the boat about 4/5 years. I turn the greaser every week when it is moored and about once when I am using at sea. I do have some water under the stern gland and only need to drain it after a couple of months or so.
How many turns of stuffing material should be inside?
I have never adjusted the stern gland nuts (one locking and one for adjusting).
Fair winds,
Lancelot

Hi Lancelot

The stuffing size will depend on your shaft/stuffing box size, mine for example is 1/4" on my stuffing box on a 1" dia shaft.

'If' you take the exisiting stuffing out you will find they will come out as rings, make sure you count them, you will probably not get as many back on again, so add as many as you can and tighten up, then undo and you will find you will get another one on.

The nuts should be tight but allowing the shaft to turn freely, then run the engine/shaft under load for about 1/2 hr, check how hot the stuffing box gets, how hot you ask, if you can grip it and not hold your hand on it's too hot, if you can grip it and hold your grip then that's not bad.

If it's just warm be happy, but monitor it for possible leaks for a couple of trips.

During the first couple of trips check again, I usualy have to adjust about twice, and no it does not leak, but I do turn the greaser two turns after each days trip, as even under sail only with the engine off the shaft is still rotating!

Hope this helps

 

[lancelot]

stern gland stuffing

I think I have some thread showing where the nut can be adjusted - I will certainly check this first.
Many thanks for the advice everyone.
Fair winds,
Lancelot

 

[Spyro]

All you need to know here

http://www.diybob.com/diyPackingGland.htm

http://www.tb-training.co.uk/10sgear.htm#bmn30

 

[Stu Jackson]

It could well happen that your material will have dried out during a haulout.

If you haven't changed in in so long, why not have a go while it's out of the water.

Whilst you can perform a replacement in the water, for the first time it wouldn't hurt.

Try this: http://www.c34.org/wiki/index.php?title=Stuffing_box_packing

and

http://www.c34.org/wiki/index.php?title=Stuffing_box

 

[Burnham Bob]

another vote for leaving it alone. if you haven't had trouble with water leaking in and you still have some adjustment left on the nuts then i would think repacking is a job that you can safely leave. when i was out of the water i used to check the stuffing box by turning the prop. if there was a slight resistance (and we're talking something you can only ust feel) then all was well.

not sure if this is a scientific method that other forumites would approve of, but i never got leaks that couldn't be remedied by a turn of the greaser and in use the stuffing box never got hot. that's a good tip above - hot means you can't keep your hand on it. if you can its just what an engineer friend of mine calls 'warm'.

when i first had a boat i got an idea of the resistance i thought was about right by (surreptitiously) turning the props on other boats on the hard.

repacking isn't a difficult job but why bother with work you don't have to do? there are usually enough real jobs on a boat

 

[Billjratt]

All you need to know here

http://www.diybob.com/diyPackingGland.htm

http://www.tb-training.co.uk/10sgear.htm#bmn30

Thanks for that link Ian.
I just read it then went to Troon and found my new shaft (the original was pitted) was onsite.
Got some of the latest stuffing from Hugh at West Coast and fitted it easy-peasy.
The box has five rings of stuffing which takes a fair bit of ramming (individually) with the adjusting flange, and there is plenty of adjustment left on the bolts with the shaft snug!
Reason for doing it was better material is available nowadays, the stuff I took out had probably been there a very long time, although it looked OK.
Pitting can be due to using the wrong kind of grease (possibly lithium?) which interacts electrically with the shaft in salt water, or so I am told.
Engine rebuilt and in shed, big splash soon I hope.

 

[Spyro]

Thanks for that link Ian.
I just read it then went to Troon and found my new shaft (the original was pitted) was onsite.
Got some of the latest stuffing from Hugh at West Coast and fitted it easy-peasy.
The box has five rings of stuffing which takes a fair bit of ramming (individually) with the adjusting flange, and there is plenty of adjustment left on the bolts with the shaft snug!
Reason for doing it was better material is available nowadays, the stuff I took out had probably been there a very long time, although it looked OK.
Pitting can be due to using the wrong kind of grease (possibly lithium?) which interacts electrically with the shaft in salt water, or so I am told.
Engine rebuilt and in shed, big splash soon I hope.

Hope it all goes to plan. I repacked mine 2 years ago with new teflon packing. I Probably don't need to tell you this but I will anyway. It leaked a bit when it first went in the water when I put it in gear. It took quite a bit of time to bed in with quite a bit of adjustment needed to get it just right. After that it's been great with only the occasional drip. First time I had to tighten it again was at the end of this year. I put a drip tray under the gland so it doesn't get into the bilges and it's easily mopped up with a sponge.