Stuffing Box Help

[kb79]

I'm sure all this has been discussed before, but my searches are coming up short. Anyhow, sorry for what must be a redundant thread, but:

Our boat's on the hard, and I'm considering repacking the stuffing box as a preventative maintenance chore. The boat is new to us as of 18 months ago, and I have no idea when the last time it was done was. So, a few questions:

1. Is this worth doing as preventative maintenance, or should I wait until it's leaking? Is there some rule of thumb as to a packing gland rework schedule?

2. It currently doesn't leak at all, even under power, and the shaft turns easily by hand. I haven't felt to see how hot it gets, but this seems a little odd to me - I've always heard that a traditional stuffing box must leak. Is mine packed wrong? If it is over tightened, shouldn't there be some shaft resistance?

3. How do I determine the size of the packing flux I'll need? I'm not sure what measurement to take, and I'm assuming the flux I remove will be unmeasurable.

Answers to these questions along with any other words of wisdom would be appreciated.

Thanks, all.

-Krister

[Weyalan]

Not exactly an expert here, but just recently re-did the packing in the stern gland on our boat, so have half a clue...

1. I don't really know. I did ask various people what the reasonable life would be, but got no firm answers. The packing is pretty cheap, so I don't think there is any hard in replacing it, and probably some good, so why not?

2. I was under the impression that ideally there should be a very slow drip with the shaft turning... maybe 1 drop every 10 seconds. I was told that the fitting could get warm, but not hot, and that if the fitting is uncomfortably hot if you place the back of your hand on it, then you have a problem

3. When you undo the packing nut, you should be able to measure the inside diamter of the recess in the nut, that contains the packing. subtract the shaft diamater from the recess diameter, and divide by two.


A couple of other thoughts:
a) You will need something to pick out the old packing, which may be very compacted / compressed.

b) We put 3 rings of now packing in, at the recommendation of the packing seller (we had the shaft out, and the stern gland off, so we could take both parts of the fitting in)

c) We were advised to adjust the fitting to the correct tension while motoring, in the water. Even with the packing nut completely undone, not much water came in and we could hand tighten until we were happy, before nipping-up the locking nut. This is actually less stressful than I had imagined, and was not a drama at all.

[Vasco]

1. Yes, by all means replace it. You'll feel better and won't be wondering anymore.

2. Some leak very little. My CS36M has a drop every minute or so when motoring. Even overtightened you might not feel any resistance. The test is whether the stuffing box gets hot to the touch when motoring.

2. I think your CS36T has a 1" shaft and takes 3/8" packing. It's not difficult to determine, you can measure when the box is clean or you can buy 5/16 and 3/8. If the 5/16 goes in too easy it takes 3/8.

While you've got the nut off to re-pack, back off the other piece and check the shaft for scoring. Tighten the box when the boat's in the water. It might take a bit of trial and error to get the proper drip.

[kb79]

great, thanks guys - looks like i've got my night planned

one last question: any type of flux you'd recommend specifically?

[Vasco]

I always use the standard packing flax, none of the fancy teflon stuff for me or the paste you put in or whatever.

[DeepFrz]

Maine Sail has a great web site with pictures and write up on how to repack the gland, among other things.

Compass Marine Project Articles Photo Gallery by Compass Marine at pbase.com

[Mark Zarley]

Sounds like your prop shaft is running very true, if it wasn't you would be tightening your stuffing box to compensate for the wear. That said if you want to replace the packing and school yourself that is a great idea. You never know when you might just have to service it while it is in the water, yes it can be done. On the other hand our shafts also run true and we have over 6,000 hrs on the last packing. So this may be the only time you will ever play with your stuffing box. That said a little installation tip, after wrapping the shaft and cutting the packing, lay it on a board and flatten it a little with a hammer. The objective is to make it a little thinner so it will slide in easier. When you tighten it down it will regain it's shape.

[motion30]

I like the gortex non drip packing

[Chief Engineer]

GFO by W.L. Gore.......

I lost count of the number of boats....including Tugs and Large Yachts I have installed it in. Most all were in the water.

[OaklandSailor]

Originally Posted by kb79

I'm sure all this has been discussed before, but my searches are coming up short. Anyhow, sorry for what must be a redundant thread, but:

Our boat's on the hard, and I'm considering repacking the stuffing box as a preventative maintenance chore. The boat is new to us as of 18 months ago, and I have no idea when the last time it was done was. So, a few questions:

1. Is this worth doing as preventative maintenance, or should I wait until it's leaking? Is there some rule of thumb as to a packing gland rework schedule?

2. It currently doesn't leak at all, even under power, and the shaft turns easily by hand. I haven't felt to see how hot it gets, but this seems a little odd to me - I've always heard that a traditional stuffing box must leak. Is mine packed wrong? If it is over tightened, shouldn't there be some shaft resistance?

3. How do I determine the size of the packing flux I'll need? I'm not sure what measurement to take, and I'm assuming the flux I remove will be unmeasurable.

Answers to these questions along with any other words of wisdom would be appreciated.

Thanks, all.

-Krister

I used this recently to do mine, and things went perfectly. You might want to use it also.

Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine at pbase.com

[bstreep]

I also the second GoreTex packing. It's a bit more expensive, but changing the packing can be a pain in the tail.

I had dental tools for removing the old packing, but frankly an ice pick worked best. We did ours a couple of weekends ago, in the water. We followed some advice here and wrapped the shaft with some WalMart bags from the outside, and pushed them a bit into the gap. Even with all of the packing out, it was just a trickle.

[Vasco]

Originally Posted by bstreep

I also the second GoreTex packing. It's a bit more expensive, but changing the packing can be a pain in the tail.

I had dental tools for removing the old packing, but frankly an ice pick worked best. We did ours a couple of weekends ago, in the water. We followed some advice here and wrapped the shaft with some WalMart bags from the outside, and pushed them a bit into the gap. Even with all of the packing out, it was just a trickle.

No need to go in the water to wrap the shaft. Wrap the shaft log and shaft with rubber from a bicycle inner tube. works fine.

[gonesail]

the GFO packing really works well. i straightened out a fishing hook to use as a tool to remove the old packing. with the GFO you may not even have a drip. you may need to contact builder to get the size of the box and packing.

[Charlie]

On the hard is good practice but it can easily be done in the water. I like the GFO packing as well. I spent two and a half hours getting the old packing out. It was a pain and I had lots of little tools to help me pick it out. My stuffing box was different then everyone elses but I managed to figure out how it worked after realizing what a stuffing box was supposed to do -- allow enough water in to cool the shaft.

There have been a few arguments here on how many drops per minute a stuffing box should release. I finally decided that it really depends on the temperature of the water and how cool your shaft is. If you are sailing in 50^ water you need less water then in 85^ water. But keep the shaft cool.