Rudder shaft stuffing box

Maintenance and refit discussion
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Rudder shaft stuffing box

Postby Antti_DD » Tue Feb 25, 2014 9:52 pm

It would be interesting to hear about your maintenance routines concerning the rudder shaft stuffing box.

When I bought the boat, the p/o said that the stuffing box is 'maintenance free' and no need to worry about. However, it started leaking a year later, on the first day of the summer cruise. Apparently the maintenance had been overlooked for too many years. Discovering that the cabin carpet is wet during sailing is not very nice finding, as your heart probably skips a beat or two. Fortunately, the leak was not much so it was nothing serious, but still enough that the water found its way from the aft part of the boat to the cabin.

This experience revealed that the so called 'maintenance free' stuffing box apparently requires some water vaseline/grease to get squeezed in the box from time to time. After this I have added vaseline a couple of times per season and it has remained watertight since then. However, I guess that the gland packing inside the box does not last forever, so it might need changing at some point. I also tried to tighten the box, but the lock nut appeared to be jammed and it is quite cramped place to operate. It would be interesting to hear if someone has changed the gland packing inside the box.
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Re: Rudder shaft stuffing box

Postby Chris » Tue Feb 25, 2014 10:38 pm

Antti, the stuffing box seems a very simple design and in this it could be mistaken for being maintenance free. It is the grease which helps maintain the seal and requires pressure from the grease cap which is periodically turned clockwise, compacting the grease. Obviously, as there is only a small amount of thread length on the cap, in time it will 'bottom out' and the cap will need removing and the grease reservoir repacking with water-proof grease.

There is a nylon seal ring at the top of the arrangement which completes the water tightness of the shaft. I am going to investigate this further before refitting the shaft as I want to be certain it is not worn. I will most probably replace it while the shaft is out and will include the procedure in a future post.

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Re: Rudder shaft stuffing box

Postby Antti_DD » Wed Feb 26, 2014 6:30 pm

Chris, thanks for the info. I guess, that now when your rudder shaft is removed, it is the best time to make sure, that the gland packing/seal are in good condition. Do you know if the box can be opened and the gland packing changed while the rudder shaft is in place?

I believe that the construction of the stuffing box is quite similar to the propellor shaft stuffing box, that I had on my previous boat. I had to tighten the gland nut a couple of times, since the box was leaking a bit too much. In case of the prop shaft, the box shouldn't be totally waterproof or too tight, since then there is a risk for overheating. In case of rudder shaft the story is a bit different and the box should be totally waterproof to my knowledge.

Here is some drawing of the rudder stuffing box, that I found from HR 352's manual. Yes, the photo is from 352, but I guess that the construction is pretty similar to 29:
HR352_rudder stuffing.pdf
HR352 Rudder Shaft stuffing box
(142.4 KiB) Downloaded 483 times
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Re: Rudder shaft stuffing box

Postby Chris » Wed Feb 26, 2014 7:16 pm

When I removed the shaft I also removed the gland nut and the lock nut revealing the nylon seal. As yet I have not had opportunity to dismantle the seal. Because of the awkward access it is difficult to see how this is constructed and the only reference I have had until you posted the HR352 pdf Antti, was the Enderlein sketch which is not very detailed. I agree that the two shaft seals will be similar.

I would imagine the gland nut and the locking nut could be loosened and the seal inspected with the shaft in place but I would doubt anything could be removed or replaced without removing the shaft.

I hope to be at the boat this weekend and I will endeavour to dismantle the components of the shaft stuffing box and let you know what I find.

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Re: Rudder shaft stuffing box

Postby Chris » Thu Feb 27, 2014 6:24 am

Antti, it appears I don't need to visit the boat to investigate the shaft seal, the answer was sat on my bench in my workshop all along! I hadn't got to this bit yet.

You now have me worried.

There was no sign of obvious leakage from the rudder shaft prior to dismantling so my intention was to merely reassemble it with just some cleaning of the components and repacking the grease gland.

Because of your problem it has made me pay closer attention to the seals and now I am concerned as to whether they are in need of replacement or not.

The fibre (or flax) appears very compressed although as you can see in the picture there is plenty of depth. It is also relatively loose on the shaft and only refitting will prove if it compresses it tight to the shaft. I would doubt it though.

I am also unsure where the seal is made. Is it on the face of the seal or between the sides if the seal and the shaft. Again I suppose a trial refit will prove this.

There doesn't seem to be anything on the HR site that helps.

I have read of people repacking stuffing boxes while afloat but I can't see how the compressed stuffing material could be removed with the gland nut still on the shaft or at least it would be very difficult as would reinstalling it. But perhaps not impossible.

Hope the picture is helpful.
Gland nut.jpg
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I found this Antti...
MVC-004F-1.jpg
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It may well be possible to repack the gland nut packing in-situ. Unpicking will be difficult but now you can see what is in there you know what needs to come out.

Ignore the difficult bit Antti. I've just pulled out the packing and it comes out quite easily. So you should be able to remove and repack it in-situ.

Thanks for drawing my attention to this as I could well have overlooked this aspect of the rudder seal maintenance.

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Re: Rudder shaft stuffing box

Postby Antti_DD » Thu Feb 27, 2014 7:57 pm

Great, very good and explanatory photos once again, many thanks for those!

One marine engineer once suggested me, that I should make a hook from a thin iron wire to collect the old packing from the stuffing box. This was regarding the prop shaft of my old boat, but it might work with this rudder shaft box as well. Just an idea, I haven't tried this trick yet.

Problem in our case is that the turning stopper appears to be frozen into the rudder shaft. So I guess that it should be removed first, before one can start to tackle the lock nut, which is probably also more or less frozen into the gland nut. Maybe applying heat would help? What tool would you suggest for heating those stuck metal parts?
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Re: Rudder shaft stuffing box

Postby Chris » Thu Feb 27, 2014 11:29 pm

The pick is a good idea Antti. A bent 'scriber' could work. If yours is packed in the same way as mine, if you can get hold of an end it should just pull out in one piece. Sometimes the packing is cut diagonally to a single circumference and laid in layers with each join staggered. The pick would come in very useful in this scenario.

I think I was lucky as the rudder had been removed a couple of years ago so the gland nut, packing, lock nut and the rudder stop all loosened easily.

I would suggest a hot air gun rather than a blow lamp and leave it playing on the shaft nuts for a good while obviously making sure the heat isn't reaching any GRP. Then let it cool a little and apply a penetrating fluid and leave it overnight. If it's been leaking there may well be green verdigris which is only on the surface and not corrosion which should crumble away. It can jam in the thread which is where the penetrating fluid is helpful. Untightening and tightening the nuts would help to break down the powder and hopefully clear the thread. As with all reluctant nuts the answer is patience, good fitting tools with good, steady leverage rather than clouting it with a hammer. If it is really unwilling, repeat the heat and try again.

The rudder stop should slide up the shaft. If the shaft is dirty or painted it might be best to remove any paint or clean the shaft to make this easier. Check the woodruff key and the keyway are not seized and are in good order. If reluctant perhaps a gentle tap with a blunt 'drift' and a hammer to loosen it. But both shaft and the woodruff are brass and are very soft so be very careful not to damage them. My woodruff key was mild steel, rusting and seized! I machined a new one from a piece of brass I had but it should be possible to buy a new one the right size fairly easily if required.

I'm still unsure of the nylon bush in the top of the outer tube. I assume this is the part which presses into the packing material and makes the seal. I just can't remember the arrangement but hopefully I will get to the boat this weekend and figure it out.

Hope I've not droned on too much but I'm just explaining how I would go about it in the hope it may be useful.

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Re: Rudder shaft stuffing box

Postby Antti_DD » Sat Mar 01, 2014 2:34 pm

Thanks for the very detailed description of the process. I think that I have to buy that hot air gun in the first place, especially as I guess that it is a useful tool also for the other maintenance work at the boat as well.

I am not quite familiar with the concept of the woodruff key. Furthermore, as the place is pretty cramped in the bottom of the aft cockpit locker, it is difficult to see how the rudder stuffing box is constructed as the turning stop is blocking the vision. I have one photo of my stuffing box taken from above, which I have been examining quite a lot lately. I have to take a closer look next time I am at the boat.
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Re: Rudder shaft stuffing box

Postby Chris » Sat Mar 01, 2014 4:01 pm

Antti, it shouldn't be too difficult to get to the gland nut.

Mind you it depends what you have in your stern locker!! Ha Ha

The rudder stop has a couple of bolts which should loosen fairly easily which clamp the stop to the rudder shaft. The stop is kept in line and locked in place by it and the rudder shaft having a groove or recess which aligns with the woodruff key.

Once the stop is loosened it should slip up out of the way and the woodruff key will drop out.

The gland nut and lock nut should then be visible. Hold the lower one (the lock nut) and loosen the top one (the gland nut). This should then slip up and this is the bit that I thought might be a bit tricky to do in-situ.

This is where the pick idea comes in. It shouldn't be too difficult to get to the stuffing material. Rake it our until you feel nothing but metal inside. Mine had some kind of plumbing mastic combined with the flax. This will just be a non-setting waterproof mastic to aid the watertightness of the material. It really needs to be all removed or it might be difficult to get a nice clean seating for the new stuffing material.
Shaft1.jpg
Rudder Shaft
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Stop1.jpg
Rudder Stop
Stop1.jpg (175.48 KiB) Viewed 6873 times
Last edited by Chris on Sat Mar 01, 2014 11:12 pm, edited 1 time in total.

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Re: Rudder shaft stuffing box

Postby Tentation » Sat Mar 01, 2014 5:28 pm

When I bought Tentation the surveyor pointed out that there was ingress of water and rust in the stern locker.
I found that the small piece of tube linking the grease pump to the stuffing box was made of poor quality steel that was very brittle. Actually it broke off when I put my hand on it. It was impossible to remove the small part of it screwed in the stuffing box. So I let it in and using a tap I managed to do a thread in it than can accomodate a clasic greaser .
could not remove the stuffing material but as there was enough place I inserted another layer of that material.
Done in 2008, greased every year and no ingress of water since then.
Graisseur de presse-étoupe arbre de barre 2.jpg
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Graisseur de presse-étoupe arbre de barre.jpg
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Red paint is anti-rust paint, now covered when twa layer of white paint.

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