Flax Break-in

[Sailing Amok]

I'm just full of questions this week.

So, I re-packed the stuffing box while on the hard. Pulled out 2 strips of 1/4 teflon packing, which surprised me, as the previous owner was meticulous and did everything right. So, I measured the stuffing box and got .180 on the callipers. Closer to 3/16 than 1/4 I figured, so put in the normal 3 bands of 3/16 (PTFE impregnated flax, that's all I could get). I coated the flax generously with Syntef shaft packing lubricant. At launch I got the box set to about 6 drips/min, and we then sailed off to our marina, which was maybe 20 min of motoring and 1 hour of sailing. I checked on the box about 10min after starting the trip, and had no drips. Once we shut down the engine to sail, I checked the  temp with my hand and it was just warm to the touch.
A few days later I loosened the packing gland until I had some drips, which seemed fine, until I tightened the lock nut and the drips stopped again. I tried this repeatedly, and every time I tightened the lock nut, the drips stopped. After doing a bit of reading, I have determined that I've been looking for drips in the wrong place all along. The only drips I have ever seen have come from the threads, not the end of the gland where the shaft enters it. However, there was a band of wet grease on the shaft, which indicates to me that something is getting through.

At no point have I tightened the packing nut beyond hand tight, and right now it is not even hand tight, still no drips from the shaft. I motored for an hour a couple days ago hoping things would change, but the stuffing box remained dry. Again it is just slightly warm to the touch, but Lake Superior is probably only 4c right now. I've ordered an IR pyrometer, which will hopefully arrive soon.

So, on to the questions:
I've heard that flax packing can take 10 hours or so to break in. Should I leave things as they are, and see if they self resolve? As long as I can hold my hand on the nut, is it safe to run like this for that period? How hot for how long does a stuffing box need to get before it will damage a bronze shaft?
Is it possible that the grease I put in there is just creating an extra effective seal, and needs to break down a bit?
Or, do I assume the previous owner had similar issues, and moved to two strands of 1/4 inch for this exact reason, and start over?

[Jim Hardesty]

A few days later I loosened the packing gland until I had some drips

Aaron & Kristina,
I avoid doing that, when tightening the adjustment the packing gets crushed and may not spring back.  Think that's more important when the packing has a season or so on it.  I start loose and sneak up to the adjustment.  I don't trust just feeling for it being warm, I use a cheep Harbor Freight laser thermometer.  My packing nut is may be a couple of degrees warmer than the shaft/ambient temp.  No more.  Certainly not warm.
IMHO  Believe a good cutlass bearing and proper alignment are necessary to having good results adjusting the packing gland.  If the shaft isn't running true it's more difficult for the packing to seal.
I use 2 rings of 1/4 inch packing, 3 won't fit in Shamrock.  Depends on the manufacture.
Jim

[scgunner]

Aaron & Kristina,

Let's keep in mind the purpose of the packing, keeping the boat from flooding while allowing enough water circulation to lube and cool the shaft. As I was told years ago by a grizzled old boatyard worker, if you can grab your packing nut and hold on to it for any length of time then it's being sufficiently lubricated, dripping or not dripping. Think about it, how does the prop shaft get damaged or scored, excessive friction heat, right? So if the packing nut only gets warm how is it going to generate enough to damage the shaft?

If it doesn't leak now it probably will down the road, at which point you can adjust it. I'd just make sure the lock nut is tight so the adjustment nut doesn't back off. Also, if you want to get a IF pyrometer for your peace of mind fine, but it's really not necessary.

[Stu Jackson]

A few days later I loosened the packing gland ... I tried this repeatedly...

I hope you've read all of the articles here:  https://c34.org/wiki/index.php?title=Stuffing_box

Jim's right, please stop loosening it, and he explained why, as do all of the stuffing box articles in the wiki.

My wiki article mentions the possibility of some boxes using 1/4" but most are 3/16" on our boats and there's another wiki link back to a thread on this forum. 

[Sailing Amok]

I hope you've read all of the articles here:  https://c34.org/wiki/index.php?title=Stuffing_box

Jim's right, please stop loosening it, and he explained why, as do all of the stuffing box articles in the wiki.

Yup, I read all of them before starting the job, that's why I was so surprised to find no drips. I had started with the nut loose enough that I figured water would be flowing out of the thing at launch. I'm also fairly certain that I got all the rings in straight and flat. All I can guess is that the flax swelled sufficiently after launch that my loose-enough nut was now too tight. I knew to expect some swelling, but maybe I underestimated it.

So if the packing nut only gets warm how is it going to generate enough to damage the shaft?

That's my thinking. I'm just hoping it is safe to go for a cruise which could potentially result in a couple hours of motoring if the wind doesn't cooperate. Hoping, as suggested, that it will eventually start dripping. Or, do I really need to get this sorted out first? I'd hate to lose another weekend of sailing, the season is so short here. And, if loosening the nut further is ill-advised, is my only option to start fresh?

Edited to fix quotes - Stu

[KWKloeber]

I had started with the nut loose enough that I figured water would be flowing out of the thing at launch.

Or, do I really need to get this sorted out first? I'd hate to lose another weekend of sailing, the season is so short here.

The test is simply to run it enough before the cruise to verify that it's staying cool.  Whether or not it drips. 

If grease is blocking the water path then it's not going to drip - there is so little water pressure that the grease will prevent a drip, but you still have the lubrication anyway (until it "needs to" start dripping.) 

Then check it often enough to put your mind a ease that it's staying cool.

[Ron Hill]

 Aaron & Kristina : As Stu said do some reading!!  If there is no water dripping and the packing gland is not hot (you can hold your hand on it) Don't do anything !!

Just make sure that you have the locknut snug against the gland nut!!

A few thoughts thought

[Stu Jackson]

Aaron & Kristina : As Stu said do some reading!!  If there is no water dripping and the packing gland is not hot (you can hold your hand on it) Don't do anything !!

Just make sure that you have the locknut snug against the gland nut!!

A few thoughts thought

Ron, I asked and he nicely answered that he HAD read the material.  There's nothing left for him to read.  His mistake was backing off the nut, that's all.

[Ron Hill]

GUYs : You all have to learn the point that Stu made.  When doing any kind of plumbing NEVER BACK UP  -  always end up tightening ! 

A thought

[Jim Hardesty]

I'm just hoping it is safe to go for a cruise which could potentially result in a couple hours of motoring if the wind doesn't cooperate. Hoping, as suggested, that it will eventually start dripping. Or, do I really need to get this sorted out first? I'd hate to lose another weekend of sailing, the season is so short here.

Aaron & Kristina,
I'd go sailing.    I'd remove anything that would move around in the aft cabin and leave the access to the shaft log open.  Then check  temp often, if it's getting too warm, go slower or sail.  If it leaks a little too much, fix it later at the dock.  You don't say what lake you're in, but they are all still cold that will help a little. 
That's what I'd do.  If you do please be very careful with the rotating shaft open.  A loose beach towel could make a mess.  Of course use caution if you get your hands, sleeves, any where around the rotating shaft.
Hope that helps,
Jim

[scgunner]

A & K,

FYI, the reason you don't back off the nut, as you've been informed by a number of people, is once the flax is compressed is it won't spring back when the nut is loosened. The problem is it creates a space which can cause some problems.

[Sailing Amok]

Thanks everyone, I'm heading the advice and not touching the stuffing box for a while (other than to feel its temp) Unless it getting pretty hot, I'll leave it alone and hope that it sorts itself out. I think I may have just been over zealous with the syntef grease. I understand the reason for not compressing the packing and then backing off, but to be honest, I just didn't think it would be such an immediate effect. I figured after only a day or so, the packing would bounce back. Obviously if it was compressed for an extended period it would not. But, it seems from the comments here that it really is a matter of once it's compressed, that's how it's staying. Anyway, Lake Superior is even colder than that one really cold corner of our ice box right now, so that should help. Off for a sail!

[Ron Hill]

Aaron : I went to school in Milwaukee and thought that Lake Michigan was cold until I went swimming in Lake Superior!!  Was at least 5-10 degrees colder!!   

I don't believe that you will ever have to worry about that packing gland getting hot!!

A thought

[Sailing Amok]

Aaron : I went to school in Milwaukee and thought that Lake Michigan was cold until I went swimming in Lake Superior!!  Was at least 5-10 degrees colder!!   

I don't believe that you will ever have to worry about that packing gland getting hot!!

A thought

Ron, we went out cruising for a few days last weekend. Fortunately the winds were favourable, so we barely motored. When we did, the stuffing box remained very cool. No wonder, the lake water temperature ranged from an almost frozen 2.7c to a balmy 6c  I don't think our swim platform will get a whole lot of use in our new home...