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Thread: Please educate me on stuffing boxes and propeller shaft bearings!

  1. #1
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    Default Please educate me on stuffing boxes and propeller shaft bearings!

    This propeller shaft actually goes into a fiberglass boat....... but the boats was actually built as a one off using a hopelessly rotten classic wooden boat for a mould..... one can say that it has now gone well past the full cirkle of the famed Ship of Theseus..... and stuffing boxes are common in wooden boats too..... so I am yet asking on this forum anyway.

    The boat is a dispacement doubleender running at 6 knots at the best.
    The "new" motor for it is an early 1980-ies Bukh DV10ME. A 10 hp single cylinder diesel. To be mounted on rubber mounts.
    The propeller shaft is stainless steel 25 mm in diametre. Straight shaft from propeller to clutch. This means that the stuffing box must be flexibly mounted to the stern tube.
    The old stern tube and the water lubricated cutless bearing in a bronze housing on the outer end of it are still there.

    The former "stuffing box" was a Volvo rubber thing like this https://www.seasea.se/motortillbeh%C...ng-volvo-penta. At 36 years old it is certainly well past the safety limit.
    I have heard awful stories abot the risk for failiour. Many years of messing with old cars and tractors and woodworking machinery have also taught me to not bet my life on anything made from rubber. The boat has no water tight compartments and no built in boyancy.
    People say I am too sceptical......... I just keep thinking that there is always a way to temporarily fix a short rubber hose well enough to pump your way home but if an entire Volvo "stuffing box" rips open you are in trouble.

    So..... consequantly I am looking for the safest possible stuffing bow.
    On a barter I got a used 25 mm stuffing box intended for flexible mounting but on closer examination it proved to be badly worn. The shaft had eaten away at least a millimetre of material on one side of the alignment bearing surface.

    Should i just look for another stuffing bow or bore out the old one and pour a babbitt bearing surface in it?
    How will the rubber in the cutless bearing react to the grease used to lubricate the stuffing box?
    Is there a way to reduce the torque load on the rubber hose holding the stuffing box so I can reduce the risk of it shearing off?

    I would be thankful for advice!
    Amateur living on the western coast of Finland

  2. #2
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    A couple of photos would help a lot. Whats the stern tube look like?

  3. #3
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    This is what the outer end looks like with cutless bearing. On the inner end there is just the end of the stainless pipe protruding from the fiberglass.
    I will take a picture of the stuffing box I have.
    Attached Images Attached Images
    Amateur living on the western coast of Finland

  4. #4
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    Here's what I'm familiar with, https://www.fisheriessupply.com/buck...ose-right-hand This is the Buck Algonquin nut style packing box with hose that gets clamped to the stern tube.

  5. #5
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    I ought one of those Volvo type rubber seals myself, having heard they were goof for 10 years of service, only to read that they should be replaced every 700 hours of running. I was previously looking at glands from Norris, with packing, definately a better long term bet, i just didnt have the funds....

    https://shop.tnorrismarine.co.uk/pag...tom-stern-gear


  6. #6
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    Add to say. You might need a water feed into the shaft for your aft cutless bearing, if there is no water feed on the outboard tube.....

  7. #7
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    Hello, heimlaga. Everything that you describe seems to be a standard, basic, shaft installation. Assuming that the cutless bearing housing is in good shape, and securely fastened to the new fiberglass hull, it should be serviceable. Check to make sure that the rubber liner of the bearing is not worn or damaged - if it is, replace the cutless bearing.

    There are two main types of stuffing boxes (sometimes referred to as 'glands') - the older screw-down type with fibrous internal packing, and the newer 'dripless' type. Both typed can be either hard-mounted or mounted via a flexible reinforced rubber hose. Small craft usually have the flexible hose mount type. The older types with internal packing are normally adjusted so that there is an occasional drip of water seeping through to the interior of the boat - the packing needs to be kept lubricated with water, so the packing nut is tightened down only far enough to allow a drop every minute or two. Your automatic bilge pump - or regular manual bilge pumping - will take care of any accumulated water in the bilge. The 'dripless shaft seal' type is just that - it seals the shaft tube completely around the shaft, relying on precision machining and plastic sealing surfaces to prevent any water ingress. They are more expensive than the older type, but need less maintenance. There used to be a lot of resistance to using them (many tales of "a friend of a friend suffered catastrophic failure and his boat sank"), but I have been specifying them on commercial boats that I have been involved with for over a decade and have not had a single failure, nor heard of one from my colleagues and clients.

    The reinforced rubber hoses that support the gland at the inner end of the shaft tube are pretty tough; they are not just any old piece of rubber hose. However, after 36 years, it is time to be changed for a new one. Your local marine supply house will be able to provide one to you to fit your gland and tube. Be sure to fasten both ends with two quality hose clamps, and not the flimsy ones used to fix your garden hose. Unless your gland packing nut is tightened way too much, there will not be enough torque transmitted to the hose from the shaft to cause it to move, much less fail.

    If the gland you have in your possession is worn from shaft mis-alignment, I would replace it with a new one. The cost is not so much that it will hurt more than the worry of lying in bed at night wondering if you repaired that old one properly.

    The 'grease' in a standard stuffing box is not (or should not be) petroleum-based grease; it is tallow or a synthetic lubricant, and is harmless to rubber. At least in my home area, you buy the stuffing box packing pre-saturated with lubricant, so you do not have to fuss with that messy job - you just cut the packing material to the proper length, insert it in the housing, and screw the packing nut down on it. No mess, no fuss.

    But, truth be told, I prefer dripless stuffing boxes...
    Hope for the best, but plan for the worst.

  8. #8
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    Thank you all...... and especially Mmd who answered most of my questions and Skaraborgcraft who linked to the Norris site where I found the Bukh workshop manual I have been looking for

    In this very case a few drops of water through the stuffing box is nothing compared to the amount of water entering the completely open boat from above as rain and sea spray.
    I have a Wickström propeller shaft mounted centrifugal bilge pump which I plan to install in the boat as an extra precaution besides an automatic electric pump and a bucket or two.

    The cutless bearing liner is pretty much worn out but it is a standard size. I have a good hydraulic press and have shifted another cutless bearing before.
    There are water openings on the forward end of the housing for the cutless bearing.

    Now I see who all cutless bearings seen locally tend to be grease sick the way rubber becomes when greased. Preople tend to use standard grease for them instead of tallow! Usually lots of grease. So I did too in the past. Thank you Mmd!

    The old stuffing box is totally chewed up inside from missalignment. So is the shaft. It seems like I must replace them both.
    plastbåt5.jpgplastbåt6.jpg
    I would like to find something similar.

    Does the water leaking inwards through the stuiffing box provide enough lubrication between the stainless shaft and the brass/bronze stuffing box?
    Amateur living on the western coast of Finland

  9. #9
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    That gland is available used on ebay, some of them look to be in good condition. search>stuffing box

    https://www.ebay.com/itm/Bronze-stuf...QAAOSwu3ZcT3pa

    Finding the heavy duty hose to connect them can be fun. Buck Algonquin has the best, it is reinforced with 4 layers of fabric mesh.
    Note the patent shaft log and the gland must both accept the same size hose.

  10. #10
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    Quote Originally Posted by heimlaga View Post

    Does the water leaking inwards through the stuiffing box provide enough lubrication between the stainless shaft and the brass/bronze stuffing box?
    Not normally. The water inlet is usually to provide water for the aft bearing and cool the gland packing in the stuffing box. I have not seen a gland where the shaft runs directly in the tube without some kind of packing, or at the very least, forced grease lubrication. The shaft log on my Koster was bronze, but there was a small seal/packing gland in the greaser unit on the end.

  11. #11
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    I just checked your photo and your stern tube has water ports for the bearing. So you only need a greaser system on the inboard end. I have two shafts with tubes up in the workshop, but they might be off an age when its imperial size, not sure when Sweden went metric, but if the shafts long enough, its easy to get a stern bearing to fit. Though postage for a shaft might be a bit expensive.....

  12. #12
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    I didnt clean it....

    PICT6092.jpg

    PICT6093.jpg

    PICT6091.jpg

    More to follow...

  13. #13
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    PICT6095.jpg

    Exit bore seems to be one inch

    PICT6089.jpg

    Shaft seems to be a 1/16th under one inch or 24mm. Plastic Biltema gauge only a guide....

    PICT6098.jpg

    It was threaded onto the end of the bronze tube. The tube could always be cut, and a rubber hose to join to your existing tube protruding inside. It never got much of a beating with a 6hp Vire. I can clean out the internal bore for a better photo if you are interested, i kept it lagged with grease and full of wax paper. The stuffing seal gasket looks fine, i can not say it was bone dry, but the boat leaked more through the planking than ever came from the shaft.

    PICT6094.jpg

  14. #14
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    I have seen a version where the stern tube and the stuffing box had two opposite quadrants machined away so that the components were mechanically prevented from rotating and the hose had no work to do beyond keeping the water out.

  15. #15
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    A modern 25 mm stainless shaft as I am aiming for is very close to 25 mm. Under one inch.

    If your stuffing box is either suitable or just undersize so that I can ream it to size then I would be very happy to take care of it.
    Do you have a reliable caliper?

    However I first need to check a local lead on a half a crate of brand new stuffing boxes. Leftovers from when Olympia (a manufacturer in Vasa) went belly up in the 1980-ies or thereabout...... I will follow it up in the next few days.
    Amateur living on the western coast of Finland

  16. #16
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    I found a 25 mm stuffing box in a boat wreck in the next village....... I just need to wait a couple of days for the ice inside the old boatwreck to melt enough so I can remove the stuffing box and find out if it's still sound. I have already talked to the owner.

    I will post the result...... I don't want skarabordcraft's nice shaft and bearing and stuffing box assembly parted out if I can scavenge the parts locally.
    Amateur living on the western coast of Finland

  17. #17
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    Default Re: Please educate me on stuffing boxes and propeller shaft bearings!

    late post,

    I know you don't want to spend money to keep your boat afloat.. and whatever floats your boat, But, PSS dripless.. it gets allot of hate and lots of love. I loved the one in my boat (Oday 30)

    https://www.deepblueyachtsupply.com/...114-shaft-seal
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

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