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Old 01-11-2017, 11:16 PM   #21
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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.
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Old 01-12-2017, 01:34 AM   #22
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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.
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Old 01-12-2017, 10:42 AM   #23
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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.
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.
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Old 01-16-2017, 05:56 PM   #24
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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!
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Old 01-16-2017, 10:42 PM   #25
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Good that it's done. Now you know what YOU need.
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Old 01-16-2017, 11:19 PM   #26
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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.
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Old 01-17-2017, 01:08 AM   #27
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The guys doing the propspeed on Monday are also prop/rudder specialists - Lex Baddiley Marine, Est 1909. .
Them or Rogers and Lough around at Brisbane Ship lifts would have been my suggestion.
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Old 01-17-2017, 03:37 AM   #28
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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.
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