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Compass Marine How To | all galleries >> Welcome To >> Re-Packing A Traditional Stuffing Box > The Stuffing Box (click any image to see a larger version)
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The Stuffing Box (click any image to see a larger version)

The Stuffing Box (click any image to see a larger version)

A few weeks ago, while digging around in some old boat parts boxes, I found the stuffing box from my old Catalina 36. It was sitting in the parts box because I had chosen to replace it with a PSS Shaft Seal to make my bilge totally dry. Today is a rainy Sunday and I though it would be a good time to rig it up in my garage and photograph how to replace the flax packing inside one of these "work horse" style stuffing boxes.

For illustrative purposes I cleaned the stuffing box of it's oxidation and grime with my drill press and a wire brush. I used a piece of 1" diameter stainless steel as my makeshift prop shaft to complete the picture and present this as it would look inside a boat.

In this picture what you are actually seeing are two nuts not one. The larger of the two is where the flax resides. The thin nut, on the left, is the locking nut. Once re-packed, & properly adjusted, you lock these nuts together with two large wrenches.

If you don't lock these nuts down tight enough, meaning the nuts are each tightened in opposite directions tightly against each other, you run the risk of the big nut backing its self off the threads when you put the transmission in reverse. There have been more than a few boats sunk by improper tightening of the stuffing box nuts.

Note:I am not advocating the used of perforated hose clamps on a stuffing box. This article was done in my shop and I used what was easily on hand to make the article work. On the day I shot this I did not have non-perforated hose clams that fit this hose. The article is about re-packing the stuffing box not about the hose clamps..

Nikon D70s
1/60s f/4.0 at 50.0mm full exif

other sizes: small medium large
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robwooly10-Dec-2012 09:16
Hi, I'm trying to work out if I should use a PPS seal or Rudder Port packing box on my Rudder for my 18 foot fishing boat..., ? which do you prefer? thanks Rob
Rich 02-Nov-2012 01:31
It is just like mine. Thank you so much for taking to time to publish this. I'm in the midst of restuffing mine now.
andy 04-Oct-2012 01:53
i repacked and replaced all hoses to our stuffing boxes. The ones we have on our Trojan F30 looks just like these. I am not getting any drips from the front of the nut only from the back/thread side. will this eventually start to drip once the three rings get worn or broke in? 1 of them was hot to the touch and the other wasnt. I loosened the nut up some and it cooled. but still only dripping from the thread side. Not sure if I should be worried or not.
BDBean 30-Jul-2012 05:02
If this nut is too tight and little/no drips will this slow the trans down enough to reduce the rpm by half? Atomic 4 1977 on O'Day. Temps at idle a little high, but at cruising rpm, climb over the top. Any relation to this packing nut issue? Love the pics as I think mine are too tight and feel no moisture on or under it.
Gene Fuller 16-Jul-2012 13:46
One additional note that I just learned. It may also be necessary to tighten the locknut to stop any back flow of water through the threads between the adjusting nut and the "box". I figured I would leave the lock nut loose until I had the adjusting nut properly adjusted but found I was getting more flow back through the threads than out along the shaft. Tightening the lock nut tightens the threads and cuts off any back flow.

Great sight. Thanks,

Gene Fuller / ESCAPDE II (1981 Catalina 27TM #4816 w/Universal 5411)
Peter Mooney 31-Jul-2011 09:01

Just to say how very helpful your site is; thank you.
I have been sitting here on my boat in Poole Harbour, UK, wondering how to deal with a leak from the stern gland. (My leak is running at 2 buckets a week rather than the recommended 3 drops a minute)

Thanks to you, I now know what to do, and where to do it.

michael W. Paul 04-Feb-2010 16:53
just found your site....thanks so muchfor pictures...makes so much sense for me...a visual guy...,going to the hareware store now to buy wrench and cross my fingers I can repair...boat sunk but fortunately on 2 feet under keel....33 Watkins...shucks....
Guest 02-Sep-2009 12:31
This is a great site!!! Made what I thought would be a tough job very easy. Thank you!!
Guest 08-May-2009 20:47
I agree about the nut coming loose when in reverse. It happened to me!
I repacked the stuffing box while on the hard. On launch day I had to maneuver
in reverse to get in and out of the area with the mast crane. Luckily we were on the boat that night. We were getting ready for bed when I noticed that the floor was wet.
I spent a tense couple of hours crammed into a cockpit locker tightening it up.
mike pomper 09-Sep-2008 15:18
what size packing would i use on a catalina 30 1 inch shaft??
Seymour Settler 10-May-2008 22:07
Thank-you for this overview. The part I am still not clear about is how to put back in the new packing cord
swanroc 08-Jul-2007 22:42
Thank you very very much-your pictures and comments have answered a question of how to lossen my box without sinking my dear old newport 28 and atomic 4.