Rudder shaft packing

I have had one rudder shaft leaking for a few months. Just hauled out this morning and have removed the old packing. There were a total of 8 rings of 1/4" packing, but the nuts had still become 'two blocked'. So I will need to add quite a lot of new packing. I can also use some washers under the nuts to get a little more travel in the fitting at the top of the gland. I did not think of doing that earlier, as I did not realise the nuts were on studs and I had run out of thread

A question. Can I simply wrap the packing around the rudder shaft in a continuous spiral? Or is best practice to have seperate rings with 45° chamfer at the ends, and offset the end joins of each ring?

Insequent said:

A question. Can I simply wrap the packing around the rudder shaft in a continuous spiral? Or is best practice to have separate rings with 45° chamfer at the ends, and offset the end joins of each ring?

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That is said to be the best way Brian. How critical it is - who knows, but as all the experts say do it that way, and it is not hard to do, why not play safe..?

Ok, just wanting to know the right way. I have removed 8 old rings of the stuff, which seems to be a lot. They may have been just 90° butted together, hard to tell now.

I am heartily sick of water in the bilge so will do it the best I can while the boat is on the hard!

I just bought some PTFE Flax packing. There is supposed to be enough in the pack for one shaft, but at best it would do 4 rings so I bought 2 packs. After I got home I noticed the pack said to use 'syntel' shaft lubricant when installing, so another visit to the chandlery before I can proceed!

Why not GFO packing?

8 rings seems like a lot. We just repacked ours and went from 6 rings to 4. I was told that with too many rings, water may not through all the rings and I could damage the shaft. We re-packed with GFO.

Consider possibly....


The Gland nut or packing squeezer should slide all the way down and nearly bottom out ....so I am not sure why yours needs 8 rings....


Unless if the kind of stuffing box that has 2 threaded studs on either side that aren't screwed in far enough like mine weren't. If so screw them in further or consider replacing them with shorter studs.

Different studs could give me another 1/2" of travel on the gland nut. That could potentially save 2 rings of packing. Maybe the gland nut is not deep enough. I also need to use a drill bit to confirm the right size - what I removed appears to be 1/4", and it seems to be a snug fit as there was reasonable resistance when I removed it.

I haven't seen any GFO here, but have not looked very hard. I think I'll try and locate a shipwright to take a look at it. I do think its a bit strange to have 8 rings of packing Maybe I need to take the rudder off to look at the whole setup.

Excuse my ignorance, what is GFO?

Rebel112r said:

Excuse my ignorance, what is GFO?

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Proprietary PTFE/Graphite impregnated fiber.

Google is your friend:

https://www.gore.com/products/gore-gfo-fiber

I found a supplier about 100km away, but not sure that I need an 8m roll of the stuff. Will try find someone at the yard that has a good rep and get some advice. The install advice on one of the GFO sites indicated to use 3 rings.

Going back to when I bought the bought the surveyor noted leaking rudder shafts. With a bit of use they seemed to take up and pretty much stopped leaking. During my refit we dropped the rudders off, and re-installed. No-one commented about the amount of packing in the starboard rudder. So I have had about 3 years leak-free performance. And the port rudder shaft does not leak at all.

I fought the same problem with rudder leaks for years. Access was terrible and it was nearly impossible to get a wrench on either the packing or lock nut. I eventually installed PSS dripless seals and have been happy with them.

One thing to double check...1/4 inch packing for your size vessel seems pretty small.


Could be...but seems small.

Rebel112r said:

Excuse my ignorance, what is GFO?

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https://www.gore.com/sites/g/files/...lant_Technologies_Overview_Brochure-Web,0.pdf

Another consideration, graphite is at the very top of the galvanic scale, make damn sure you have bonded the rudders properly if you use graphite. Don't use it at all if you have an aluminum boat!

psneeld said:

One thing to double check...1/4 inch packing for your size vessel seems pretty small.


Could be...but seems small.

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Rudder shafts are 2". Using some drill bits as a gauge it looks to be 5/16" gap. In that case part of the problem may have been the 1/4" packing in there. The lower most ring was pretty chewed up, not sure I have all of it out yet.

Access is not easy, and we have a heat wave. Its 35°C at 9am with 50% humidity, lasting for a few days, staying hot at night. I'm not enjoying confined spaces. It seems I melt quite easily, drenched in sweat without even doing much physical activity at all. The prop/rudder specialists at the yard are back from break on Monday. I'll talk to them then, and do something easier like remove the old anodes in the meantime.

Xsbank said:

Another consideration, graphite is at the very top of the galvanic scale, make damn sure you have bonded the rudders properly if you use graphite. Don't use it at all if you have an aluminum boat!

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Yes, rudders are well bonded and its a GRP hull. Rudder zinc anodes seem to dissolve fastest of all my anodes, so going to a larger size this time around.

Insequent said:

Rudder shafts are 2". Using some drill bits as a gauge it looks to be 5/16" gap. In that case part of the problem may have been the 1/4" packing in there...

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Hobo's shaft is 2" also and I think the PO used 1/4". The new 5/16" fit perfect.

Insequent said:

Rudder shafts are 2". Using some drill bits as a gauge it looks to be 5/16" gap. In that case part of the problem may have been the 1/4" packing in there. The lower most ring was pretty chewed up, not sure I have all of it out yet.

Access is not easy, and we have a heat wave. Its 35°C at 9am with 50% humidity, lasting for a few days, staying hot at night. I'm not enjoying confined spaces. It seems I melt quite easily, drenched in sweat without even doing much physical activity at all. The prop/rudder specialists at the yard are back from break on Monday. I'll talk to them then, and do something easier like remove the old anodes in the meantime.

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Kind of a big difference between 1/4 and 5/16 packing...doesn't seem like much but it is.

If even anything but snug on a 5/16 drill bit....could even be 3/8 which my shafts and rudder packings use for 1 1/2 inch shafts.

No, definitely not 3/8. The 5/16 drill is really snug.

You might be surprised.....but probably not as Larry pointed out what his is.


Maybe on mine, the thinner shaft for similar stuffing box components needed the 3/8....I had to really compress then almost beat mine in...but 5/16 was too loose.

Rudders typically do not need any fancy packing. The PTFE you bought will do fine. Waxed flax packing would do also although it would not have the expected life of the PTFE as the flax will break down. The success is more about your workmanship in doing the job.

Note: On the prop shaft I do use the GFO, not a copy. The prop shaft turns fast and can build heat. The rudders are a very slow moving device and can be snugged up to not leak with the standard PTFE.

Yes, cut the rings on a 45o angle. A butt may leave an opening. A spiral may leave a leak path. NOte: " MAY" but it's often enough of a pain to do the job that it pays to do it right. This method of packing fitting is not confined to just boats so the guidelines have been arrived at from a wide range of uses. Stagger each cut at 120o or 90o based on how many rings installed. Just don;t stack the cuts one atop the other.

There can be too many rings. Too many can lead to inconsistent crush and then leaks. 8 is to many. Usually 3 or 4 rings is enough.

It sounds like you have the type of box that has an oval flange with two studs on the oval ends and then two nuts on each stud used to push the compression ring and compress the packing.

The machined THREADS the nuts operate on should be hidden almost entirely by the two oval ears when the compression ring is dropped in without any packing. If not then the studs may not be set properly or the threads improperly cut, threaded section too short or the wrong stud chosen.

A short tube of bronze could also be used to make up for lack of thread length or some silicon bronze nuts that have had the threads drilled out so they slide on the studs. More than one way to deal with the threads.

These are good stuffing boxes and should only need attention every few years other than an adjustment now and again once set up.

Put some anti seize on the stud threads so the nuts don't seize to the studs. It can simply be a heavy grease.

Use a tamping tool on each ring to tamp down into the recess. Tools like screwdrivers can poke holes and damage the rings. I use PVC pipe cut into halves. . Mine has limited space to the compression ring so I use several different lengths of pipe halves. If you have the clearance you may not need different lengths.

Once all rings are installed compress the packing slowly , moving the rudder through several swings after tightening the nuts somewhat and keep repeating until you start to feel some resistance. Ensure the nuts , side to side, are tightened as evenly as possible.
The swinging will move the packing rings and help it to compress evenly and not hang. There is a feel to it. Once compressed then wait until it is in the water and do a final compression check. After a few hours of operation you may need to do it again. For a rudder you should be able to stop leaking.

Thanks for the detailed info. It is the type of gland you describe.

The guys doing the propspeed on Monday are also prop/rudder specialists - Lex Baddiley Marine, Est 1909. Its now operated by his son Paul, and I spoke with him today as he came back for a short while today to get the boat next to me (Codene, 33.5m Expedition yacht) back into the water ASAP.

If it were simply a case of new packing I would already be doing it, but I'm concerned about the depth in the gland. There is over 2.5" of space to fill. Its almost like the bearing is not long enough. The compression flange only has about 1" of travel, 30% of which can't be used with existing studs. I want their assessment of whether it can just have extra packing rings of the correct size or whether there is something more that needs to be done to get an outcome that will be leak free for an extended period.

Insequent said:

Rudder shafts are 2". Using some drill bits as a gauge it looks to be 5/16" gap. In that case part of the problem may have been the 1/4" packing in there. The lower most ring was pretty chewed up, not sure I have all of it out yet.

Access is not easy, and we have a heat wave. Its 35°C at 9am with 50% humidity, lasting for a few days, staying hot at night. I'm not enjoying confined spaces. It seems I melt quite easily, drenched in sweat without even doing much physical activity at all. The prop/rudder specialists at the yard are back from break on Monday. I'll talk to them then, and do something easier like remove the old anodes in the meantime.

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I had to do the same job. The stuff I bought wouldn't go in, so I tore some apart and wound in smaller strands until there was enough, tightened it up and 12 years later still dry.

I now have 5 rings of 5/16 PTFE flax packing installed. Apparently the packing depth is typically 2/3 of shaft diameter, but in my case the depth was over 2.5" on 2" shaft. Original bearing might be a bit short. The compression ring is also relatively short and does not have all that much effective travel, hence the need for more rings of packing than usual. I have a 6th packing ring ready to add after it all beds down, but am advised I likely wont need it.

In retrospect I might have been able to add a ninth ring of 1/4" packing as a temporary measure some months ago. Always something to learn!

Good that it's done. Now you know what YOU need.

Brian, do you have good access? It sounds as if you do.
Recently I admired a boat with a hinged lift up perspex cover over each fully accessible gland.

Insequent said:

The guys doing the propspeed on Monday are also prop/rudder specialists - Lex Baddiley Marine, Est 1909. .

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Them or Rogers and Lough around at Brisbane Ship lifts would have been my suggestion.

The boat was on the hard just 3m from Baddiley's shop door, and they were doing the propspeed so it made sense to talk to them about it.

Access is fair. You can see the top of the gland and get one hand in from either front or rear. Or forget looking at what you are doing, re-position and get both hands in, one at front and one at rear, and work by touch/feel.