Repacking stern gland in water

[Theo]

One of those old fashioned bradawls (or was it a gimlett?) that joiners once used with a small screw thread on the end.

https://www.amazon.co.uk/Gimlet-4-5mm-Pack-1-U-G0475/dp/B001L5PF7G?ie=UTF8&*Version*=1&*entries*=0

Gimlet.

 

The bradawl (cf Brad, a cut nail, and awl a pokey thing for bodging holes) is the thing that looks like a little screwdriver with a slightly over large handle.

[Theo]

Theodora's stern gland is right under the engine and really difficult to repack. When we bought the boat the water flowing in could be stopped by a turn or two of the greaser but as soon as the propeller had done a few revolutions it was spraying out water. At the first drydocking we had a water lubricated gland which has a graphite ring running against a stainless ring to provide the rotating seal. I don't think that it has let in a drop of water in the 5000 hrs that it has run.

 

Nick

[Guest]

Gimlet.

 

The bradawl (cf Brad, a cut nail, and awl a pokey thing for bodging holes) is the thing that looks like a little screwdriver with a slightly over large handle.

cheers I can never remember which is which..

Theodora's stern gland is right under the engine and really difficult to repack. When we bought the boat the water flowing in could be stopped by a turn or two of the greaser but as soon as the propeller had done a few revolutions it was spraying out water. At the first drydocking we had a water lubricated gland which has a graphite ring running against a stainless ring to provide the rotating seal. I don't think that it has let in a drop of water in the 5000 hrs that it has run.

 

Nick

Is that a PSS seal?

[Scholar Gypsy]

I think it all depends on the boat. Last time I repacked the gland, after a good squirt of grease, I took all the old stuff out, added some new rope, and tightened it up,

 

Not a single drip of water.

[RLWP]

I think it all depends on the boat. Last time I repacked the gland, after a good squirt of grease, I took all the old stuff out, added some new rope, and tightened it up,

 

Not a single drip of water.

 

I did that on a Dutch Barge/Klipper where the stern gear was further under the water than a narrowboat. Again, no leaks

 

Richard

[ditchcrawler]

 

I did that on a Dutch Barge/Klipper where the stern gear was further under the water than a narrowboat. Again, no leaks

 

Richard

Probably still less than 0.5 psi

[RLWP]

Probably still less than 0.5 psi

Which seems an awful lot when water is coming in;)

 

Richard

[clbrof]

Thanks for all the info guys. The boss behind the stern packing section leaks from the threads. It initally leaked from the boss (hull) so I tightened with a stillson. This in turn loosened the other end a 1/10 of a turn and a small amount of water leaked through the threads there. I undid the packing sections and wound it off a bit to expose the threads. In doing so I ended up taking the whole thing off (tentatively), not a drip came through, was a bit anti-climatic.... (was ready with cling film to put through the weed hatch).

 

I put some marine sealant on the threads and rewound the packing section back on. I inspected the packing, seems very hard with what seems like parts of string falling apart and burn grease coming out..... Bit annoying after 80 hours, I assume it was overtightened. I have put everything back together and will get some new packing soon to repack it.

Edited May 16, 2016 by clbrof

[Theo]

Probably still less than 0.5 psi

 

Doing the sums shows that in fresh water, if the stern gland is at a depth of 1m the pressure will be 1.423 psi.

 

N

[bargemast]

 

Doing the sums shows that in fresh water, if the stern gland is at a depth of 1m the pressure will be 1.423 psi.

 

N

 

That seems to be right, as every 10 metres is 1 bar, 1 bar is 14.23 psi, so if you move the point 1 number to the left you end up with the answer you gave.

 

Peter.

Edited May 17, 2016 by bargemast

[ditchcrawler]

 

Doing the sums shows that in fresh water, if the stern gland is at a depth of 1m the pressure will be 1.423 psi.

 

N

But most Narrowboats are less than 2 feet Overall depth and the prop shaft less than half of that. To have the propshaft at 1Mt would probably result in an overall draft of about 2Mts and you wouldn't get far on the UK canals in that.

[RLWP]

But most Narrowboats are less than 2 feet Overall depth and the prop shaft less than half of that. To have the propshaft at 1Mt would probably result in an overall draft of about 2Mts and you wouldn't get far on the UK canals in that.

It would match the gland I was talking about though

 

Richard

[bargemast]

But most Narrowboats are less than 2 feet Overall depth and the prop shaft less than half of that. To have the propshaft at 1Mt would probably result in an overall draft of about 2Mts and you wouldn't get far on the UK canals in that.

 

I don't see how you get to an overal draft of 2 Mts when the prop shaft is at 1mts, if you ad half the prop diameter + 2" to 3" for the clearence between prop and skeg, you have all you need, you'll be still fare away from your quoted 2 Mts.

 

Peter.

[Theo]

 

That seems to be right, as every 10 metres is 1 bar, 1 bar is 14.23 psi, so if you move the point 1 number to the left you end up with the answer you gave.

 

Peter.

Ah! but I used h rho g and got the answer in N/square metre. Google then converted it to libs per squin for me.

 

N

[Guest]

 

That seems to be right, as every 10 metres is 1 bar, 1 bar is 14.23 psi, so if you move the point 1 number to the left you end up with the answer you gave.

 

Peter.

Clever this metric innit? I wonder how our imperial system ever got off the ground? That said when I were a lad you got 240 pence for your pound, now you only get 100

[bargemast]

Clever this metric innit? I wonder how our imperial system ever got off the ground? That said when I were a lad you got 240 pence for your pound, now you only get 100

 

It's not very fair isn't it to give you only 100 pence for your pound nowadays, while you used to get 240 pence

 

Peter.

[Theo]

Clever this metric innit? I wonder how our imperial system ever got off the ground? That said when I were a lad you got 240 pence for your pound, now you only get 100

 

We went to the 16th century merchant's house in Conway. It seems that they had 64 or something like that different units for volume. Every commodity had its own unit convenient for the quantities of that commodity. Metric is simple but to cook in grammes is a bit daft. The gramme is far too small a unit for cooking even strong spices come in 1/4oz bits. 1/4oz it about 7g. 454g to the lb. Very silly.

 

N

[Peugeot 106]

I am thinking about repacking my stern gland. I would like to do this afloat but due to the gap between the shaft clamp and gland pusher being so small I will need to slide the prop shaft back about 4 to 6 “ to get the pusher out and access into the gland. I realise I need to fill the shaft with grease while rotating it before starting but will all the grease be pushed out when I slide the shaft backwards to get clearance. I can get access to the propellor through the weed hatch .

Has anybody done this or would I be better doing this out of the water? I realise I could use a bin bag but is there too much that can go wrong?

Thank you

[Tracy D'arth]

7 minutes ago, Peugeot 106 said:

I am thinking about repacking my stern gland. I would like to do this afloat but due to the gap between the shaft clamp and gland pusher being so small I will need to slide the prop shaft back about 4 to 6 “ to get the pusher out and access into the gland. I realise I need to fill the shaft with grease while rotating it before starting but will all the grease be pushed out when I slide the shaft backwards to get clearance. I can get access to the propellor through the weed hatch .

Has anybody done this or would I be better doing this out of the water? I realise I could use a bin bag but is there too much that can go wrong?

Thank you

Always do it in the water, piece of cake. I have even changed the stern bearing tube whilst in the water a number of times but then I make sure there is a good bilge pump running first!

If you wrap polythene or cling film around the shaft in front of the prop up against the bearing it will stop 99% of the water getting in.

[OldGoat]

Off the top methinks you principal problem in pushing the shaft back will / migh be that the rudder wiil be in the way of the shaft  for 4 inches.

Anyway why do you need to mobe the propshaft anyway?  I just  remove the stuffer plate and pushed the packing into the space with very little water ingress (if any).

[Peugeot 106]

11 minutes ago, Tracy D'arth said:

Always do it in the water, piece of cake. I have even changed the stern bearing tube whilst in the water a number of times but then I make sure there is a good bilge pump running first!

If you wrap polythene or cling film around the shaft in front of the prop up against the bearing it will stop 99% of the water getting in.

Thanks but will it not leak when I slide the shaft back?

[Peugeot 106]

9 minutes ago, OldGoat said:

Off the top methinks you principal problem in pushing the shaft back will / migh be that the rudder wiil be in the way of the shaft  for 4 inches.

Anyway why do you need to mobe the propshaft anyway?  I just  remove the stuffer plate and pushed the packing into the space with very little water ingress (if any).

I can slide the prop shaft ok. If necessary I can take the clamp off completely. My problem is that I cannot get access to the gland as I can’t slide the pusher back far enough. I need to slide the shaft.  I’ve done it before on dry land easy enough when I had the engine out but haven’t tried it afloat

[Tracy D'arth]

7 minutes ago, Peugeot 106 said:

Thanks but will it not leak when I slide the shaft back?

Slide the cling film up to the bearing.  It will if you pull the shaft right out, then you need a cork.

[BEngo]

Put a jubilee clip, or a really tight large cable tie, on  the inner end of the shaft so you cannot accidentally push it right out.  The rudder usually prevents this anyway.

 

N

[Tony Brooks]

3 hours ago, OldGoat said:

Anyway why do you need to mobe the propshaft anyway?  I just  remove the stuffer plate and pushed the packing into the space with very little water ingress (if

 

I am with this. I have no idea why you need to push the shaft back, It won't give any more clearance between the "stuffer" and the gland face. Maybe you think you need to remove the stuffer but as long as there is a gap with the stuffer pulled forward between the stuffer and face of the gland equal or a bit larger than the packing thickness I don't see why you can't do it the "normal" way. It may make more sense to take the coupling off the shaft before messing with the gland, so you have more working room, but is seems a faff.