Stern gland greasing - why?

[Ubergeekian]

I doubt whether grease and Cutless bearings are compatible and suspect that greasers are a legacy of the days when metal bearings were used.

So long as you re-pack the gland when it runs out of adjustment, you should have few difficulties.

I had a long chat with a Victoria Shadow Association expert this evening, and his recommendations were that (a) the original setup works just fine and (b) greasing it is pointless. I'm happy to accept his advice on both points, partly because he has owned the same hull and engine as me for 27 years and I've had mine for six weeks and partly because keeping things as they are will cost me less.

Now all I need is a double jointed pygmy gorilla which can clean and rebuild stern glands to save me the yard fees.

 

[Neil_Y]

You're absolutely right as others have said here.

Stuffing boxes work very well with just water, water is a great lubricant and coolant. The bearing in the stern tube also relies on water to lubricate and cool.

Grease is a very poor conductor of heat and what happens in some cases is that excessive grease use can make its way to the bearing causing it to over heat and fail prematurely.

It seems in the UK it has become a tradition (I was brought up with this type as well, and there are many out there) but I really can't see why it is any better than a straight water system.

 

[NormanS]

Gland packing is generally made with either graphite, or now probably more often, teflon lubrication built in to the packing material, and as such doesn't need grease. Grease, however will not do it any harm.

If your packing gland is attached to the stern tube with a bit of rubber hose and jubillee clips (argh!), and will therefore not support the shaft, the tube will require some sort of bearing at the fore end, which, unless it is a Cutless bearing, will require grease lubrication.

If the packing gland is rigidly attached to the stern tube, the packing will give sufficient support to the shaft, and in common with most applications of traditional packing, will not need extra lubrication.

Either case assumes that there is a water lubricated Cutless bearing at the ouboard end of the stern tube.

In service, grease will not adversely affect a Cutless bearing, but when dried out, over a winter, in the absence of water, grease may cause a Cutless bearing to swell, and bind to the shaft. (Bitter experience).

 

[mcframe]

Absolute living hell to reach. The only access is over the top of the engine. This is one reason that I am paying Windjammer - who have a skinny engineer on the books - to do it.

Hahaha - a couple of years ago I dismantled & remantled the heat exchanger on a friend's Nic 45 - it involved crawling on top of the engine, in the ~8" gap between the engine and the cockpit sole - my mate (~16 stone, 6'3") couldn't fit; his wife (4'9") could fit, but didn't have long enough arms once she got there....

 

[Neil_Y]

I don't like to directly disagree but in this case our experience as a bearing supplier is that grease can edversley effect a cutless bearing. Grease (build up or excessive use of a greaser) can build up in a running system to such an extent that it can restrict water flow through the lubricating and cooling channels of a bearing designed to run with water as the lubricant and coolant.

The main problem is not bearing swell, but heat as grease is a very poor codnductor of heat. The heat can cause the bearing material to expand, deteriorate or both. More of a problem on faster and larger shafts due to shaft speed so yachts may never see this but it is something to be aware of.

 

[Burnham Bob]

As far as I know, all traditional stuffing boxes needs grease to actually complete the waterproof seal - it's not for lubrication as such.

My old boat had a greaser attached directly to the stuffing box and the grease reservoir was in the cap - held about a heaped teaspoonful.

Now have a remote greaser on the new boat which holds much more and is far more convenient. Only problem is filling it from a tin of grease as it's a bit of a reach from the cockpit locker. Rather than a grease gun I bought an icing set from a kitchen shop and use that - fill the syringe and squeeze it out into the greaser. Only need to do it once or twice a year.

I turn the greaser after running the engine until I feel resistance and that's it. If you have to have a greaser (and you probably do) go for a remote one.

 

[ironmaiden]

Gland packing is generally made with either graphite, or now probably more often, teflon lubrication built in to the packing material, and as such doesn't need grease. Grease, however will not do it any harm.

If your packing gland is attached to the stern tube with a bit of rubber hose and jubillee clips (argh!), and will therefore not support the shaft, the tube will require some sort of bearing at the fore end, which, unless it is a Cutless bearing, will require grease lubrication.

If the packing gland is rigidly attached to the stern tube, the packing will give sufficient support to the shaft, and in common with most applications of traditional packing, will not need extra lubrication.

Either case assumes that there is a water lubricated Cutless bearing at the ouboard end of the stern tube.

In service, grease will not adversely affect a Cutless bearing, but when dried out, over a winter, in the absence of water, grease may cause a Cutless bearing to swell, and bind to the shaft. (Bitter experience).

the inboard gland or stuffing box is not there to support the shaft, if it is the usual set up connected to the stern tube with a section of reinforced hose, it is there to stop water from entering the boat via the stern tube and the hose plays a vital part.. it allows the shaft to be flexible. if your engine is mounted on rubber flexible engine mounts then your engine will be able to move 360 degree, in relation to the centre of the shaft. without that small piece of hose to take up that movement you shaft would wear VERY VERY quickly or in some cases even bend where it enters the gland/stuffing box.
you should only have a fixed inboard bearing if you engine is fixed ridged to the engine bearers and there is no movement ...not recomended as the vibration will be awfull amongst other things.

with regards to the packing; it should be three rings of the correct size cross section for the size of gland/stuffing box and each ring must have its ends cut to meet at an angel/bevel NOT as a 90 degree butt... when fitting the rings into the gland the first ring should have its joint at 12 o'clock, the second ring with its joint at 4 o'clock, and the third rings joint at 8 o'clock this ensures that there is not a continuous free passage for the water as there would be if all the joints were in line.

the grease; there were odd packing glands that were made to run without grease but, they do perform better with a SMALL amount of grease as the packing can over time dry out, this is not good, by providing the packing with a small amount of gease you are re-lubricating and sealing it, but dont over do it, and if your access is bad then I would go for the remote greaser try to get a second hand one it will work fine , there is very little to go wrong with them.

finally, my opinion for what its worth, I would not entertain a modern shaft seal on "simunye"
I have built her shaft configuation using the good old stuffing box..that wont let me down.. and if it did I know I can fix it anywhere in the world.. even at sea, due to the simplicity of them.

regards rachel.

 

[vyv_cox]

you should only have a fixed inboard bearing if you engine is fixed ridged to the engine bearers and there is no movement ...not recomended as the vibration will be awfull amongst other things.

Unless it's an Aquadrive!

 

[Poignard]

you should only have a fixed inboard bearing if you engine is fixed ridged to the engine bearers and there is no movement ...not recomended as the vibration will be awfull amongst other things.

My boat has had a fixed inboard bearing and a flexibly mounted engine for 45 years. It's really time I did something about it!

 

[ironmaiden]

Unless it's an Aquadrive!

agreed but the the OP is asking about stern glands/stuffing box.
regards rachel

 

[vyv_cox]

agreed but the the OP is asking about stern glands/stuffing box.
regards rachel

Oh, sorry. I thought it was you who raised the subject of fixed inboard bearings?

Vyv

 

[ironmaiden]

My boat has had a fixed inboard bearing and a flexibly mounted engine for 45 years. It's really time I did something about it!

for not that short of 35 years I have repaired/replaced many many set ups such as yours, either the white metal bearing or the shaft or both worn due to the stern tube set up being ridged and the engine flexing on mounts,
may I ask if your set up has a flexible coupling between the gearbox and the shaft coupling?
and how great a distance is the fixed inboard bearing from the engine?
you have been very lucky to have had no wear in 45 years.

regards rachel.

 

[ironmaiden]

Oh, sorry. I thought it was you who raised the subject of fixed inboard bearings?

Vyv

should you care to read it, my reply was also with regard to the quote in my post re; "the hose would not support the inboard end of the shaft",
regards rachel.

 

[Ubergeekian]

the grease; there were odd packing glands that were made to run without grease but, they do perform better with a SMALL amount of grease as the packing can over time dry out, this is not good, by providing the packing with a small amount of gease you are re-lubricating and sealing it, but dont over do it, and if your access is bad then I would go for the remote greaser try to get a second hand one it will work fine , there is very little to go wrong with them.

Where does the remote greaser put the grease in? On top of the stuffing rings or to one side?

(Sorry about the basic questions...)

 

[Poignard]

for not that short of 35 years I have repaired/replaced many many set ups such as yours, either the white metal bearing or the shaft or both worn due to the stern tube set up being ridged and the engine flexing on mounts,
may I ask if your set up has a flexible coupling between the gearbox and the shaft coupling?
and how great a distance is the fixed inboard bearing from the engine?
you have been very lucky to have had no wear in 45 years.

regards rachel.

It now has a Centaflex coupling which I fitted about 12 years ago, before that it had an R&D coupling which is much more rigid. Also the engine is a BUKH, which runs very smoothly, and it is mounted on rather stiff rubber mounts.

I can't remember the distance between the gearbox flange and the stern gland but I know it is less than the length of the smallest Aquadrive (I have checked because I wanted to fit one but had to settle for the shorter Centaflex!).

My reply to your post was a bit facetious (apologies for that) and I absolutely agree with your concerns about flexibly-mounted engines and fixed stern shafts. However, I think there are many things on boats which are far from perfect but function well enough in practice to be tolerated. When I eventually have to re-engine, I intend to fit a Yanmar 1GM10 and an Aquadrive but the BUKH obstinately refuses to die, meanwhile things stay as they are!

Like you, I prefer the simple reliability of a packed gland and a fixed inboard bearing. Nothing much to go wrong, and if it does it is easily repaired, anywhere in the world, without the need for spare parts. Even if a leak cannot be fixed straightaway the amount of water coming in is easily coped with by a normal bilge pump.

 

[ironmaiden]

Where does the remote greaser put the grease in? On top of the stuffing rings or to one side?

(Sorry about the basic questions...)

please don't apologise if we don't ask we don't learn.

the connection of the tube from the remote greaser is usually on the top of the stuffing box for easy acces but it doesn't have to be, it can be to the side or bottom, as long as grease gets to the packing. the grease usually enters the gland between the first and second rings of packing, (looking aft) and the rotation of the shaft will spread it to the remainder of the packing rings.

regards rachel.

 

[ironmaiden]

re; parsifal,

you might be waiting a long long time for the buhk to give up the gost..... dam good engine!

 

[ghostlymoron]

Where does the remote greaser put the grease in? On top of the stuffing rings or to one side?

(Sorry about the basic questions...)

My arrangement is as shown below. The greaser is connected outboard of the gland. I have a remote greaser, quite large I will borrow SWMBOs icing attachment and re-pack (she won't notice till next Christmas cake!!)

 

[vyv_cox]

please don't apologise if we don't ask we don't learn.

the connection of the tube from the remote greaser is usually on the top of the stuffing box for easy acces but it doesn't have to be, it can be to the side or bottom, as long as grease gets to the packing. the grease usually enters the gland between the first and second rings of packing, (looking aft) and the rotation of the shaft will spread it to the remainder of the packing rings.

regards rachel.

What you are describing is a lantern ring lubricator, common on some centrifugal pumps used for non-hazardous products. Years ago I had books that described these for stern glands but I've never come across one. The greaser on mine was located immediately astern of the packing rings, where grease injected may have reached the packing but probably not. No lantern ring though. Interested to know if you have come across any?

 

[alahol2]

My arrangement is as shown below. The greaser is connected outboard of the gland. I have a remote greaser, quite large

That photo could almost have been taken on my boat. As can be seen from the photo, plenty of grease gets to (and through) the packing. I usually end up with a little pile of grease in the bilge under the gland. The stern tube also fills with grease though I have never noticed any exiting from the cutless bearing.