Constant drip stuffing box shaft seal

[Fr J Hackett]

Most boats I have seen have the 'stuffing box' version of seal. I would suggest it is not a US or UK thing at all ... as its a universal seal design used not only for drive shafts - but also to seal valve stems ... pump shafts .... many uses in fact due to its ease of service and success.

The 'packing' used normally is impregnated with 'persistent water proof grease' .... plus the addition of a greaser unit.

As mentioned above - the seal is set so it drips about 1x every 20 secs or so WHEN SHAFT IN USE .... this provides the 'cooling' ...
When shaft is stopped - its common practice to use Greaser to introduce more grease to reduce drip to a minimum. In fact once you get to 'know' your boat - you can actually inject just enough to stop the drip. Once shaft is in use again - that 'extra' grease is soon dislodged and drip starts again.

When changing packing ... its easy to see if improper use has been ... not enough or too much grease ... if its the white packing - then it will show 'burnt brown' where its had lack of water / grease ..... (a small trace of brown is normal).

?

 

[Refueler]

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It is actually based on the few times we forget to grease or packing hasn't seated well on first replacement ....

The amount of brown IF there is tiny. But if significant amount - then seal has been badly installed or maintained.

 

[Porthandbuoy]

If it ain’t broke . . .

 

[Fr J Hackett]

It is actually based on the few times we forget to grease or packing hasn't seated well on first replacement ....

The amount of brown IF there is tiny. But if significant amount - then seal has been badly installed or maintained.

I think you missed the point. ?

 

[jwfrary]

I have never come across a stuffing box with no form of ‘greasing’, normally supplied by a tube from the grease reservoit, but as can be seen from Viv Cox’s site there is a type where the grease reservoir is part of the stuffing box.
Surely there must be some form of greasing, otherwise the stuffing would run dry and wear very rapidly?

Theres no need for a greaser with modern types of packing material.

The grease used to be for when you had a white metal tail bearing, which have all but disappeared in favour of cutlass bearings. The grease will probobly shorten the life of the cutlass bearing!

If they want to add a greaser then they can of course, but it's not something I would knock money off for!

 

[Refueler]

Theres no need for a greaser with modern types of packing material.

The grease used to be for when you had a white metal tail bearing, which have all but disappeared in favour of cutlass bearings. The grease will probobly shorten the life of the cutlass bearing!

If they want to add a greaser then they can of course, but it's not something I would knock money off for!

I have to disagree.

Why would any manufacturer provide a packing seal with greaser if as you say - its only for 'white metal' system ? How many boats do you imagine are out there in the world with greaser equipped packing seals ? Must be thousands if not millions ... funny that they haven't cottoned on yet ??????

 

[Tranona]

I have to disagree.

Why would any manufacturer provide a packing seal with greaser if as you say - its only for 'white metal' system ? How many boats do you imagine are out there in the world with greaser equipped packing seals ? Must be thousands if not millions ... funny that they haven't cottoned on yet ??????

But, as explained in several posts the grease is not there to lubricate the seal - that is done by water, hence the need for the slow drip. The grease is there to fill behind the packing to stop drips when the shaft is not turning. The grease point is BEHIND the packing and the grease goes down the stern tube. It was also used as noted to lubricate white metal bearings often fitted at the inboard ind of the stern tube as in in the once common Stuart Turner stern tube.

Have a look at the the link in Post#2 at the photo of Pete's stuffing box in his Neptunian 33. This exactly the same as originally in my GH with the actual seal on the end of a long rubber tube and the greasing point is on the housing at the stern tube where originally there was an option of a white metal bearing. The rubber tube fills with grease to slow the flow of water. If it was there to lubricate the packing the injection point would be at the packing.

I have ditched this monstrosity of half baked "engineering" and had a cutless fitted to provide intermediate support for the 1.6m long shaft and the outside of the housing machined to take a Radice lip seal .

 

[arcot]

No greas fitting.
.
Green Teflon goo
.
Packed around 1/4 rounds of square flax packing.
.
Slight drip at normal speeds.
.
Temperature of water 18 C
.
Temperature of stuffing box 22 C

Teflon goo is wonderful.