What size packing for this stuffing box ?

[NahanniV]

I'm refurbishing my stuffing box.

Last season was the first time I had the boat in the water and the stuffing box leaked more than I would like (1Drip/second). No amount of tightening would stop it.

I have the shaft coupling off and the box off. But I'm not sure what size packing to order ? I thought it would be a simple calculation: stuffing box i.d. - shaft o.d. / 2. But looking at the packing nut makes me wonder.

The nut where the packing goes is only partly threaded, see picture, so there is the thread i.d.(1-7/8") and then the larger i.d. where there is no thread(2"). The un-threaded space is 3/4" long. The shaft is 35mm (1-3/8") (whole boat is an annoying mix of metric and imperial).

The failed packing seems to be 3* 1/4" flax packing with a wider ring of green goo (syntef?) between the first and second rings. So one of the flax rings was compressed more by the threaded part of the nut.

I'm thinking of using Gore GFO packing.

I think I could put 3 rings of 5/16" packing into the nut and then slide it onto the shaft since I have everything apart, but what about replacing it on the shaft? Will I be able to push 5/16" packing through the 1/4" space between the threads and the shaft ?

Would 3 rings of 1/4" compress enough to fill the space ?

The box also has a grease fitting aft of the packing.

Any thoughts welcomed.

Cheers,
JM.

[HappyMdRSailor]

The good news????

Packing is CHEAP!!!!!!!!!!!!!!!!!!!!

Buy both sizes....

Test fit is the way to go... But if were me I would try all 5/16" (kinda normal size for 1-3/8 shaft) ... If it didn't fit, 2 rings 5/16, and 1/4 in the threaded portion... Keep trying fits until you are happy with the space fill before smishing.... Read all the info about diagonal tapered end cuts, and staggering ends...

Just my take.... Other opinions soon to follow and discredit accordingly....

(edit) Don't forget to replace your shaft log and clamps with shiny new stuff while this is apart...

[Tynesider]

Originally Posted by NahanniV

I'm refurbishing my stuffing box.

Last season was the first time I had the boat in the water and the stuffing box leaked more than I would like (1Drip/second). No amount of tightening would stop it.

I have the shaft coupling off and the box off. But I'm not sure what size packing to order ? I thought it would be a simple calculation: stuffing box i.d. - shaft o.d. / 2. But looking at the packing nut makes me wonder.

The nut where the packing goes is only partly threaded, see picture, so there is the thread i.d.(1-7/8") and then the larger i.d. where there is no thread(2"). The un-threaded space is 3/4" long. The shaft is 35mm (1-3/8") (whole boat is an annoying mix of metric and imperial).

The failed packing seems to be 3* 1/4" flax packing with a wider ring of green goo (syntef?) between the first and second rings. So one of the flax rings was compressed more by the threaded part of the nut.

I'm thinking of using Gore GFO packing.

I think I could put 3 rings of 5/16" packing into the nut and then slide it onto the shaft since I have everything apart, but what about replacing it on the shaft? Will I be able to push 5/16" packing through the 1/4" space between the threads and the shaft ?

Would 3 rings of 1/4" compress enough to fill the space ?

The box also has a grease fitting aft of the packing.

Any thoughts welcomed.

Cheers,
JM.

Hi

I am not sure that 1/4" will be large enough, I have a 25mm (1") shaft and I use 1/4" and the stuffing box takes 3 coils of stuffing.

You should have counted the number of coils that you removed and will you find you can not get the same on again, fit as many as possible and refit stuffing box and tighten up, then undo it and you will find you can fit another coil of stuffing.

Also remember to cut the stuffing at 45 degrees and to stagger the joints.

I then run the engine (in gear) for five minutes, 10 min and then 30min, checking the stuffing box tempreture each time and adjust accordingly.

My box runs quite hot, but you should be able to grip it and hold it with your hand, in 3 hours of engine running time I get about a saucer full of water.

[HappyMdRSailor]

JM,

Did you get this sorted out ????

Or almost freeze to death trying???

Just keeping tabs on ya buddy...

[NahanniV]

Took your advice and ordered both sizes.

The weatherman is promising warmer weather for the weekend !

The other day they were still ice fishing on the harbor.

Hard to believe launch is in a month.

Cheers,
JM.

[redsky49]

I think the compelling determiner is the un-threaded inner portion length of 3/4". If using (3) 5/16" wraps (resulting in a stacked height greater than the space allowed) won't you start to shift the aft most wrap when you tighten the lock nut and the threads contact the stuffing, and would this not deform the wraps - allowing water to pass through?

I would be more inclined to try the 1/4" Gore Tex stuffing with three wraps. When you tighten the lock nut the wraps will compress to less than the installed depth, but will also expand radially (relative to the shaft) to seal tightly against both the inner surface of the stuffing box and the surface of the shaft.

I also would not add anything in addition to the flax/Gore Tex stuffing.

Interesting question.

[HappyMdRSailor]

Originally Posted by NahanniV

Took your advice and ordered both sizes.

The weatherman is promising warmer weather for the weekend !

The other day they were still ice fishing on the harbor.

Hard to believe launch is in a month.

Cheers,
JM.

Good luck... And hopes of shirt free sailing in the distant future bud!

[NahanniV]

Ok, so now I have tried both.

5/16"
- two rings fit in the un-threaded part of the nut.
- it is a snug fit and tightens up quickly.
- the nut must be off the shaft for the packing to be fitted.

1/4"
- three rings fit in the un-threaded part of the nut (might be able to get 4 after tightening).
- it is very loose and requires a lot of compression before it starts to feel tight on the shaft.
- it can be fitted with the nut on the shaft.

I guess I'll go with the 1/4" unless someone convinces me otherwise ?

Cheers,
JM.

[redsky49]

I think the fact that you could install three rings of the 1/4", but only two of the 5/16", shows you are on the right path with the 1/4".

I wonder if the metric/Imperial issue is having some impact?

[HappyMdRSailor]

Originally Posted by NahanniV

Ok, so now I have tried both.

5/16"
- two rings fit in the un-threaded part of the nut.
- it is a snug fit and tightens up quickly.
- the nut must be off the shaft for the packing to be fitted.

1/4"
- three rings fit in the un-threaded part of the nut (might be able to get 4 after tightening).
- it is very loose and requires a lot of compression before it starts to feel tight on the shaft.
- it can be fitted with the nut on the shaft.

I guess I'll go with the 1/4" unless someone convinces me otherwise ?

Cheers,
JM.

JM,

Gone for a week... Would have suggested 4 x 1/4"...

Hope ya have it sorted !