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Packing Gland


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59 minutes ago, D Ash said:

Yes , I see what you mean.  Just re-read Alan's advice and that certainly seems what he is implying.

Would the "cut at +/-120 degrees" also be a good idea?  a bit like railway tracks 

 

 

It was but maybe I didn't explain it very well.

 

The cut of each ring should be 'out of alignment' with the one before it by 120 degrees (for a 3 ring system, and 90 degrees if you have 4-rings)

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1 hour ago, D Ash said:

Yes , I see what you mean.  Just re-read Alan's advice and that certainly seems what he is implying.

Would the "cut at +/-120 degrees" also be a good idea?  a bit like railway tracks 

 

The cut at an angle is known as a skarf and in an ideal world you would skarf the joint in the packing to make it even more waterproof but in my experience it's all too easy make the strands in the packing fray out and also to get the packing ring too long or short so in the end you get a worse joint than if you cut it at 90 degrees. So for the inexperienced I would advise cutting 90 degree joints. Try the fancy stuff when you have got a few repackings under your belt.

 

For clarity I am talking about the cutting of the packing, not the displacement of the cuts around the shaft.

Edited by Tony Brooks
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Thanks to all for those comprehensive answers.   I feel more confident at having a go at this myself when the time comes.

One other concern now arises. How fast is the water ingress likely to be once the old packing is taken out?  In the video demo. (a dry run) the packing was clean and was easily extricated with no indication of how fast water might be flowing in.   will the flow have a bearing on how easily the new packing will go in etc etc  I don't want to lift her out every time the packing needs doing 

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3 minutes ago, D Ash said:

I don't want to lift her out every time the packing needs doing 

 

There could be many, many years between needing to re-do the packing.

If you really wanted you could do it (say) every alternative time that you come out for blacking (ie 4-6 years) but that would probably be much more frequent than actually required.

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You dont need the boat out of the water to repack a stern gland of this type. 

Squeeze the grease down before you start, probably a bit more than you would after a cruise.

Get your 3 pieces of packing measured up on the prop shaft, cut and ready to go.

Then remove the old packing with a pick or long screw.

Insert the new packing with the joins at 12 o'clock, 4 o clock and 8 o clock in case all those 120 degrees confuddled you. Easiest way of getting it to slide in uniformly, is to push the bearing outer against each packing to get it in the gap.

Once in, tighten the 1st nut on each shaft, shaft should still be able to turn, and then lock 2and nut on.

Then run engine in gear for a couple of minutes, bearing should not get hot, if it does, slackened nuts slightly.

 

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16 minutes ago, D Ash said:

Thanks to all for those comprehensive answers.   I feel more confident at having a go at this myself when the time comes.

One other concern now arises. How fast is the water ingress likely to be once the old packing is taken out?  In the video demo. (a dry run) the packing was clean and was easily extricated with no indication of how fast water might be flowing in.   will the flow have a bearing on how easily the new packing will go in etc etc  I don't want to lift her out every time the packing needs doing 

If you are worried, ensure the bilge pump is working. A poly bag wrapped around the shaft down the weed hatch where it sticks out before the prop will stop any leak.

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1 hour ago, D Ash said:

Thanks to all for those comprehensive answers.   I feel more confident at having a go at this myself when the time comes.

One other concern now arises. How fast is the water ingress likely to be once the old packing is taken out?  In the video demo. (a dry run) the packing was clean and was easily extricated with no indication of how fast water might be flowing in.   will the flow have a bearing on how easily the new packing will go in etc etc  I don't want to lift her out every time the packing needs doing 

 

Normally not  a lot if any, especially f you screw the greaser down hard, but with a badly worn shaft and bearing it might be quite a lot but unlikely to be more than the bilge pump can cope with.

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8 hours ago, John Lewis said:

Packing went in - 3 wraps of 8mm... Do I need to grease down the whole tube, as this is a cruiser stern with about 5ft of stern tube?

 

Thanks

 

Keep turning the the greaser until it becomes stiffer.

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