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Thread: Shaft Packing

  1. #1
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    Default Shaft Packing

    Wandering Star is out of the water. One of the things I am doing is replacing shaft packing on the prop and rudder shafts. The packing gland on the prop shaft is outside the hull, tightening with two bolts rather than one big nut. I was surprised to pull 7 wraps of packing out, there seems still to be more. It gets harder to remove as I go deeper, I am using a set of Craftsman picks. I put in four of the loops in the last ten years, who knows how old the rest might be.
    The rudder shaft uses a more standard set up, one big nut on pipe compressing the packing. It has some old hard grease on it. I think any waterproof grease will do, but I'm curious what you do.

  2. #2
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    Default Re: Shaft Packing

    This packing extractor tool by Buck Algonquin was used by the guys at the shipyard that I last worked at. They were very enthusiastic about the tool; said there was no other tool near as good. Locally it costs about twenty bucks for the 12" tool, a shorter one is available for a few bucks less.



    Most builders I know do not use any grease in their packings, but rely on the tallow-impregnated packing, or the more modern impregnated graphite type of packing.
    Hope for the best, but plan for the worst.

  3. #3
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    Default Re: Shaft Packing

    Sounds to me like something is amiss if you have 7+ wraps of packing.


    As you can see, there should be i lip to compress it against inside the unit.

  4. #4
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    Default Re: Shaft Packing

    Yep, as Michael said, a standard packing pulling tool.

  5. #5
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    Default Re: Shaft Packing

    Thanks, I ordered two.

  6. #6
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    Default Re: Shaft Packing

    All good advice above, but surely you must another packing gland at the forward end of the shaft to keep th Nags in alignment?

  7. #7
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    Default Re: Shaft Packing

    Quote Originally Posted by Paul Schweiss View Post
    All good advice above, but surely you must another packing gland at the forward end of the shaft to keep th Nags in alignment?

    Except stuffing boxes / packing glands are not intended to act as bearings, so you are actually better off with only one. Besides, there would be no water (lubrication and cooling) for the inner one.

  8. #8
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    Default Re: Shaft Packing

    Fair enough Nedl, though I would say that having a bearing at both ends of even a short shaft keeps things running smooth. The more common cutless bearing at the stern connected to a shaft packing gland at the inboard end being fairly common, the flax packing properly applied and tightened do act as a bearing.
    The only vessel I have ever seen here on the West Coast was a lovely Tahiti Ketch we took care of, it was built on Matinicus Island(my customer, the builder, was a Harvard grad who served with the first Marine combat brigade in Vietnam, this was his mental health/anti-PTSD project) It had a packing nut on the sternpost, but the casting had the usual ears that protruded on each side to scoop water into the normally used cutless bearing. In this vessel the water went forward inside a bronze tube connecting the aft and forward glands to lubricate the packing gland at the forward end.

  9. #9
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    Default Re: Shaft Packing

    The tools worked well, until the very end where the packing was pretty much loose fiber. I have pulled 17 wraps out, not a typo, 17. It makes sense as the packing is 1/4" and the gland is 4+" deep, do the math.
    There was old, hard grease in the rudder post bearing. I scraped and sprayed it out. The packing in there was pretty worn too. I guess it needs attention in every century.

  10. #10
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    Default Re: Shaft Packing

    You might have a pillow bearing on a very long shaft but every normal boat I have ever seen has the shaft actually supported at it's two ends, rear by the cutless and front by the coupling to the engine. The only time the stuffing box acts a little as a bearing is when you are twiddling the motor mounts as you get the flanges of the coupling gapped at the same few thousanths all the way around before tightening it all up. The stuffing box is not a bearing.

  11. #11
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    Default Re: Shaft Packing

    Quote Originally Posted by Ian McColgin View Post
    You might have a pillow bearing on a very long shaft but every normal boat I have ever seen has the shaft actually supported at it's two ends, rear by the cutless and front by the coupling to the engine. The only time the stuffing box acts a little as a bearing is when you are twiddling the motor mounts as you get the flanges of the coupling gapped at the same few thousanths all the way around before tightening it all up. The stuffing box is not a bearing.
    Absolutely correct.

  12. #12
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    Default Re: Shaft Packing

    There may be a bushing in the stuffing box but it is not for shaft support and should have more shaft to bushing clearance that would be normal for shaft support, it is a "throttle bushing" and is there to reduce/throttle the water pressure on the packing this is common practice for stuffing boxes on pumps of all operating pressures and could well be on the stuffing box of a prop shaft as well.

  13. #13
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    Default Re: Shaft Packing

    You may be right, eggman, but I have never seen one in thirty-five years in the game.
    Hope for the best, but plan for the worst.

  14. #14
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    Default Re: Shaft Packing

    I was a machinist for a couple of pump shops for many years and it was the norm for pump stuffing boxes, cant speak to prop shaft stuffing boxes though thought I would chime in with my experience.........

  15. #15
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    Default Re: Shaft Packing

    Quote Originally Posted by eggman918 View Post
    There may be a bushing in the stuffing box but it is not for shaft support and should have more shaft to bushing clearance that would be normal for shaft support, it is a "throttle bushing" and is there to reduce/throttle the water pressure on the packing this is common practice for stuffing boxes on pumps of all operating pressures and could well be on the stuffing box of a prop shaft as well.
    Quote Originally Posted by mmd View Post
    You may be right, eggman, but I have never seen one in thirty-five years in the game.
    The dynamic, pressures and flows generated in a stern tube are totally different than in a pump. Hence their non appearance in stern tubes.
    It really is quite difficult to build an ugly wooden boat.

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  16. #16
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    Default Re: Shaft Packing

    Some images ripped from the web.











    Here is the type John (the OP) has, I think, based on his description. The, "guts," are the same as above.
    253 300 - baymarine.us
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  17. #17
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    Default Re: Shaft Packing

    eggman, at six feet of depth (more than most boats that we talk about here) the pressure on the stern packing is about 17.5 psi. In a typical 3" shaft gland (again, larger than most boats discussed in the WBF), the total pressure on the packing would be abut 45 lbs. I suspect that this is greatly below the operating pressures of the pumps you are familiar with. I am not discounting your experience, but merely pointing out that the pressures experienced in boat shaft packing systems is low enough that mechanical complexity is not required to ameliorate it. If there is any principle that has held up in ship design over the past century or more, it is the KISS principle.
    Hope for the best, but plan for the worst.

  18. #18
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    Default Re: Shaft Packing

    The old girls that I play with normally have a v strut cutlass, an I strut with a cutlass, the shaft log tubed with lead, then a packing gland followed by a cooper bearing, a muff coupler, sometimes a second cooper then the engine coupler. Port and starboard. We will be in Woodenboat this year, maybe the new shaftlogs will be hanging in the new floor timbers by then. BTW if you are looking for wide 8/4 white oak, there isn't any, we cleaned everybody out. New frames, new floors, new keel, new planks, etc, etc.

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