Stuffing Box & Packing Material Choices

[tenders]

Not sure why I never thought of tracking down nice thin fixed wrenches for those packing nuts! Now to research the diameter of my gear....

My ire for shaft seals, which has been forged with 25 years of experience with the one I just replaced with a traditional packing gland, lies in the fact that the bellows replacement requires removal of the engine coupling from the shaft. This is an incredibly frustrating job in my vee-drive installation. The last straw this spring was spending three days trying to press it off, making zero progress, and having to cut the shaft anyway. Never again - the packing gland is pretty good and can be serviced much, much, much more easily.

 

[goldenstate]

I am afraid I am in the same situation you are with the locking nut. You read my blog post about fiddling with the stuffing box. I'm not sure I was really able to free the locking nut. The adjusting nut was relatively easy to rotate.

I don't know what the right way to do is to free the locking nut once the adjusting nut has come off. One can't torque against the rubber hose and the bronze is soft. So, prayer and PB blaster?

I'm following your progress here with great interest, but few suggestions.

 

[vanilladuck]

Interesting Tom! I was curious if anyone else had hit this combination. I don't think I've marred or bent the bronze on the round part just forward of the black hose. Just using light pressure from the pipe wrench to keep it from torquing on the hose. I'll post some updates after I give it another try today.

Doing some searches, I found this post on another forum. It talks about giving the flat of the lock nut a decent 'whack' with a hammer. Not sure how reasonable this is:

PB Blaster and Stuffing Box Adjustment

This question is probably more for the attention of Maine Sail, but posted in the open forum if of general interest. Needing to tighten up a bit on my traditional flax type stuffing box (recently dripping a bit too much after five good years since the last new flax was packed), I first read...

forums.sailboatowners.com

 

[goldenstate]

Bryan - Do you mind sharing your temperature readings for your propeller shaft at rest, and then after having run for 15 minutes?

I'm guessing that if you were at 3-4 drops per minute at rest you should have had few problems with overheating.

I'm about to take my boat for a longish drive and this would be an opportune time to collect some similar data.

 

[vanilladuck]

Update
Tried a light "whack" with a hammer on the flat of the lock nut, sprayed Kroil at 10-15m intervals, and with solid but gentle force tried to pry the lock nut loose. Hasn't budged yet. Trying more today.

Tom, you bet! All temps in Fahrenheit, taken with an Etekcity Lasergrip 800 Digital Infrared Thermometer at a distance of 8-10", and with laser aimed at the exposed Monel shaft:

Cold, still, no motor running	70.0	69.9	69.9
Running forward at idle after 15m	70.1	69.6	70.6

Indeed negligible differences and no issue with overheating. At rest the drips are about one per second (~60 per minute) and after rotating the shaft or wrenching on the lock nut it speeds up to 2 drips per second (~100-120 per minute)

 

[goldenstate]

Thank you! Sounds something like an average of the air temp in your boat and the water temp the other end of the shaft is sitting in.

I'll report my temps today if a couple of things go my way.

 

[vanilladuck]

Update - SUCCESS!

I got smart tonight and tried working the lock nut forward towards the engine and the stuffing box nut. Since the stuffing box nut was already loose I just backed it off until I have a number of threads exposed. The lock nut budged a wee bit and then I worked with the Kroil and a bronze brush to scrub the green corrosion from the threads. Back and forth, Kroil, brush, back and forth... Eventually it was turning freely on the threads using my hand and no wrench.



I tightened up the stuffing box nut until the drips stopped and I could still turn the prop shaft with my hand. Then tightened the lock nut against the stuffing box nut using equal amounts of pressure on the two wrenches. I'll test it tomorrow with temp readings.

 

[goldenstate]

Good work/idea on rolling the locking nut forward instead of reverse.

I gave a couple of taps on mine yesterday with a hammer and it still didn't want to budge. I think I need to revisit the lubrication strategy. Haven't tried Kroil before, only PB Blaster.

I drove my boat across the bay yesterday for a couple of hours. My stuffing box does not drip at rest and only maybe a drop per minute under way. This condition is with the adjusting nut backed off so I can adjust it with my hand alone.

At rest my prop shaft temp was @ 73 degrees.
Under way, (after 30 minutes at 2800rpm) the shaft temp had risen to 87 degrees.

I was driving through Gilroy this weekend with my family and the air temp was 109 degrees.
Unless there is a tolerance issue I don't understand I'm thinking 87 degrees is just fine for my 1" steel prop shaft and won't do any harm.

 

[Alan Gomes]

Good work/idea on rolling the locking nut forward instead of reverse.

I gave a couple of taps on mine yesterday with a hammer and it still didn't want to budge. I think I need to revisit the lubrication strategy. Haven't tried Kroil before, only PB Blaster.

I drove my boat across the bay yesterday for a couple of hours. My stuffing box does not drip at rest and only maybe a drop per minute under way. This condition is with the adjusting nut backed off so I can adjust it with my hand alone.

At rest my prop shaft temp was @ 73 degrees.
Under way, (after 30 minutes at 2800rpm) the shaft temp had risen to 87 degrees.

I was driving through Gilroy this weekend with my family and the air temp was 109 degrees.
Unless there is a tolerance issue I don't understand I'm thinking 87 degrees is just fine for my 1" steel prop shaft and won't do any harm.

What you describe is a perfect adjustment. I'd leave it alone.

 

[goldenstate]

What you describe is a perfect adjustment. I'd leave it alone.

Thank you! As to temperature, I thought the same.

My concern is that I have a 1/8 to 1/4" gap between my hand-tight adjusting nut and my frozen locking nut. I think if I get the locking nut freed and tightened up against the adjusting nut, I think I will have achieved 'normal operating state.'

 

[Alan Gomes]

Thank you! As to temperature, I thought the same.

My concern is that I have a 1/8 to 1/4" gap between my hand-tight adjusting nut and my frozen locking nut. I think if I get the locking nut freed and tightened up against the adjusting nut, I think I will have achieved 'normal operating state.'

In my experience, I typically do not need to use a wrench to snug up the packing nut against the packing. Or, when I have used a wrench, I still go very lightly. You can easily overtighten and that will lead to overheating.

Seriously, if you can get no drips at rest and a slight dripping while underway, you're golden. Just work on getting the locking nut free, which you need to do no matter what, and you'll be in great shape.

FYI, I'm reproducing below an email correspondence I had with one of the techs from Buck Algonquin, a stuffing box manufacturer. It contains info about temperature issues. I know I've posted it before on this forum, but I'm appending it below for your convenience. You'll see that he thinks temps even of 130-deg. are fine. Mine are much more like what you are describing, though--all the better!

*****

From: stevegaston62@gmail.com [mailto:XXXXX@gmail.com] On Behalf Of Steve Gaston
Sent: Saturday, May 08, 2010 9:57 AM
To: Alan Gomes
Subject: Re: Packing box issues

Dear Alan,

We have seen the variations in the packing sizes that you have described. 95% of my packing box questions revolve around the goretex graphite based packing. It is good packing. However, most people misinterpret the instructions and believe it is drip free. All three material (graphite, Teflon, and flax) have their drawbacks.

Flax. low cost. temperature tolerance minimum. abrasive. Does require water for cooling and lubrication.

Teflon. medium cost. High temperature tolerance (packing only). mildly abrasive. Does require water for cooling and lubrication.

Graphite. higher cost. High temperature tolerance. least abrasive. Does require water for cooling and lubrication.


The common theme here is they all require water for cooling. I do not believe you will get a much better setup than the goretex running at the 130 degrees. The temperature will vary with the amount of water drip through the packing and the shaft speed.

The other components have a reasonably high tolerance to heat. The packing box hose is made of the same materials as marine exhaust hose. The bronze and stainless are not a relative heat consideration.

The abrasion factor would be the other consideration. Since the goretex has the least abrasion impact, it would be the better choice.


I hope this helps.

Best Regards.

Steve


Steve Gaston
Buck Algonquin Co., Inc.

 

[vanilladuck]

Tom, those temps sound pretty close to mine, as you'll see below. Drips on my boat aren't as well controlled as yours, but I'm happy with the improvement. I went sailing today and tested the shaft/stuffing box temps at different places following my adjustments last night.

All temps in Fahrenheit, taken with digital infrared temp gun at least a few seconds apart. I also took temps in two places: 1) on the exposed Monel shaft 2) on the brass stuffing box nut itself.

Sitting at the dock this morning; absolutely no drips observed from the stuffing box

Still, engine cold, nothing moving, measuring the shaft (stuffing box nut had similar temps but I didn't record)

65.4

65.8

66.6

65.9

At dock, running in forward gear at idle for 15m; absolutely no drips observed from the stuffing box

Shaft	79.1	81.2	83.4	81.0
Stuffing Box Nut	89.9	87.0	90.6	91.4

Seeing absolutely no drips tells me the stuffing is doing a great job, but it's probably not getting any water to help lubricate the shaft and flax. So, I adjusted the stuffing box nut out about 1/4 turn and then tightened the lock nut.

Sitting at the dock; running in forward gear at idle for 15m; observed about 1 drip every 10 seconds from the stuffing box

Shaft	79.5	76.5	76.3	78.7
Stuffing Box Nut	89.1	87.2	90.0	90.0

This seemed okay, so off we went to go sailing. After motoring for a few minutes I checked again.

Underway @ 2000rpm for some time; observed about 1 drip every 6 seconds from the stuffing box

Shaft	82.1	85.8	83.0	82.8
Stuffing Box Nut	99.9	99.0	97.2	97.8

So, now the drips are a wee fast at one every 6 seconds (10dpm) while motoring and one drip every 30 seconds (2dpm) with the shaft still. The stuffing box nut seems to be absorbing a lot of the heat build up while the shaft is staying under a 20 degree delta from sitting still. I'm sure there's some variance in water temp between the marina and the channel, but I'm willing to ignore that I think this is passable, but I may adjust a bit more next trip out on the water. Esp. after seeing the email response that Alan got from Buck Algonquin above (thank Alan for including that!)

 

[Alan Gomes]

Well, Bryan, you are certainly attacking this with an admirable thoroughness and gusto! You are living up to your boat's name.

Those temps you are seeing are totally fine; you have absolutely nothing to worry about. And if it doesn't drip after the boat has been sitting a while, that's as good as you are going to get it. If that's the case, button it up and have a beer!

The point is, you do need moisture to lubricate the shaft, as Steve Gaston pointed out. I'd not bother checking the shaft temperature but take your readings on the packing nut with an infrared thermometer. A slow drip while in gear is plenty good enough--even if it's only a few drips a minute. In fact, if you can see a small bit of water glistening right where the shaft exits the packing nut on its way to the transmission coupler, you probably have what you need to keep it cool. It doesn't take much water to keep it cool, but it does take some.

If you do err, it's better to let it drip slightly too much than not enough. You can always try sneaking up on the ideal adjustment in small increments if you are seriously concerned with dialing it in just so.

Mine actually has been quite good for a long time. I haven't touched in maybe a few years? I don't remember exactly, it's been so long. I am using the synthetic GFO Goretex packing. The stuff is bulletproof. For me, it does not drip at rest but does weep a bit of water while in gear. It does not run hot. For a while I had a remote temperature probe on the packing nut to monitor it, but the monitor croaked and I didn't bother replacing it because at that point I was confident enough in how it was adjusted.

Edit: I think I misread your signature line. I assumed "Semper Explorans" was your boat's name. But then I looked up and see that it is actually named "Rumor"? So "Semper Explorans" is more of a personal motto?

 

[vanilladuck]

Thanks, Alan! A few beers have been consumed while working on various things. I like your advice - one more is due I bought some 1/8" GFO packing and will probably use it to replace whatever is inside the stuffing box when the time comes.

Boat's name is "Rumour". As explained by the seller, "nothing travels faster." Semper Explorans is a Latin phrase that stuck with me after, of all things, purchasing a journal to use as my first ship's log (pictured below). I was drawn by the compass rose and didn't notice the words at the bottom of the cover until I held it in my hands. I've always enjoyed learning new things, hobbies, history, techie things, etc, so it seemed to fit.



ps - updated my signature a tad

 

[Alan Gomes]

Thanks, Alan! A few beers have been consumed while working on various things. I like your advice - one more is due I bought some 1/8" GFO packing and will probably use it to replace whatever is inside the stuffing box when the time comes.

Boat's name is "Rumour". As explained by the seller, "nothing travels faster." Semper Explorans is a Latin phrase that stuck with me after, of all things, purchasing a journal to use as my first ship's log (pictured below). I was drawn by the compass rose and didn't notice the words at the bottom of the cover until I held it in my hands. I've always enjoyed learning new things, hobbies, history, techie things, etc, so it seemed to fit.

View attachment 35155

ps - updated my signature a tad

Cool ship's log!

 

[Kenneth K]

Boat's name is "Rumour". As explained by the seller, "nothing travels faster."

Bravo!

 

[nquigley]

What's the correct size of packing flax?
I'm guessing a 2' length is plenty?

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[tenders]

2’ is plenty but the diameter depends on the design of the gland.

 

[Christian Williams]

Get a couple of diameters and plan to take the wrong one back.

 

[nquigley]

Get a couple of diameters and plan to take the wrong one back.

Thanks. I dug out the Manual tonight - said I need 1/8" packing... now I read the rest of the thread above, I see that's what Bryan used.