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MedSailor 05-07-2013 12:10 AM

Hot stuffing box...
 
My boat is finally out of the yard!!!

Happy. Had to get that off my chest. :D

I had a bunch of alignment work done that ended up requiring a new prop shaft. I had also asked to have a dripless shaft seal installed because my stuffing box was supposedly shot. It turns out the old bronze stuffing box is still viable and putting in the dripless wasn't an option.

Now the weird part. My stuffing box takes TWELVE strands of 1/4" packing. That's a lot of packing. The yard I used said they've had problems with the graphite and the PTFE packing and prefer good ol' flax, so that's what they put in there.

I took it out for a short spin and at 2000RMP (1000@ the shaft) the box was dripping 2-3 drips per second but the water dripping out was very hot. The stuffing box was also very very warm/hot to the touch. The shaft itself, just forward of the box wasn't very warm.

So how hot is too hot? I imagine that having 12 strands of the stuff will mean I've got some serious friction so I might need more than just a few drips to keep it cool....

MedSailor

tjvanginkel 05-07-2013 12:26 AM

Re: Hot stuffing box...
 
We just had a stuffing box installed. We were told that about 90 - 100 degrees farenheit was an acceptable temp. Or hot to touch but not so hot that you could not keep your hand on it. I can't remember if that was just for the breaking in period. Maybe I better find out....
Don't know how its going to work out as we are still in the yard! 1 more week.......

sailvayu 05-07-2013 07:29 AM

Re: Hot stuffing box...
 
12 strands sounds wrong, almost every one I have repacked took 3 maybe 4. How do you know it took 12?. Do you have a picture of the stuffing box?

BubbleheadMd 05-07-2013 07:34 AM

Re: Hot stuffing box...
 
Ok, totally skipping the oddess of 12 strands of flax, and that these people are eschewing the new packing material, I think what you should do, is buy an IR thermometer from Harbor Frieght and get an actual temperature of the stuffing box.

They are cheap, and will tell you if you're carving a collar in your shaft.

Oh- I think Zeehag has a Formosa. You might try asking her about this.

sony2000 05-07-2013 08:02 AM

Re: Hot stuffing box...
 
My new flax took many adjustments by an unexperienced sailor, myself. Drips while stopped , and temperature while running, are important. Drips while running, is less of a concern until it has worn in.
Start to loosen the cap to get the first two right.
Try to turn the shaft by hand, before using the engine.

copacabana 05-07-2013 09:15 AM

Re: Hot stuffing box...
 
I also think that 12 rings sounds wrong. Did you see them packing the stuffing box? What problems have they encountered with the new graphite stuffing? It is so much better than traditional flax and you should be able to adjust your stuffing box to run with no drips and remain cool. Personally, I'd ask the yard to re-do it and I'd stand over them while they repack it. Insist on using graphite stuffing though!

MastUndSchotbruch 05-07-2013 09:27 AM

Re: Hot stuffing box...
 
Quote:

Originally Posted by MedSailor (Post 1026596)
My boat is finally out of the yard!!!

Happy. Had to get that off my chest. :D

I had a bunch of alignment work done that ended up requiring a new prop shaft. I had also asked to have a dripless shaft seal installed because my stuffing box was supposedly shot. It turns out the old bronze stuffing box is still viable and putting in the dripless wasn't an option.

Now the weird part. My stuffing box takes TWELVE strands of 1/4" packing. That's a lot of packing. The yard I used said they've had problems with the graphite and the PTFE packing and prefer good ol' flax, so that's what they put in there.

I took it out for a short spin and at 2000RMP (1000@ the shaft) the box was dripping 2-3 drips per second but the water dripping out was very hot. The stuffing box was also very very warm/hot to the touch. The shaft itself, just forward of the box wasn't very warm.

So how hot is too hot? I imagine that having 12 strands of the stuff will mean I've got some serious friction so I might need more than just a few drips to keep it cool....

MedSailor

Seems all wrong to me. I put in maybe 3 strands of packing (don't remember the details, years ago), of the new-fangled Teflon stuff. No drips while stationary, one drop every few seconds while running, and cool as a cuke. Same temp as the ocean outside.

Something is wrong in your setup.

JimsCAL 05-07-2013 10:33 PM

Re: Hot stuffing box...
 
2-3 drips per SECOND!!! That's essentially a constant stream! And it's still hot?

MedSailor 05-08-2013 12:58 AM

Re: Hot stuffing box...
 
Thanks for all the replies so far. I'll try and provide more useful information....


I didn't stand over them when they packed it, but I DID interrogate the yard worker personally who did the work. He told me that he was able to get all the stuffing of differing diameters out of there easily when the prop shaft was out. He was able to see that the portion you pack, which is where the bronze packing gland and nut are threaded to a stainless tube (instead of the usual hose) there was a LOT of room for packing.

He told me that the packing was 1/4" diameter, and that he thought long and hard about 11 or 12 strands but decided I'd probably need the extra adjustment and went for 12. He tells me that these things almost always take 3 or 4 strands and he's never seen one quite like mine. Off the top of his head he remembered that the strands were each 5 3/4" each and that he used about 70" of packing total.

These guys, by the way, are the former yard mechanics of Bayliner/Maridian. When Bayliner went out of business they all followed their old yard boss to the new yard in Anacortes. They really do seem like a competent bunch, and this isn't my first time in the yard.

So I take them at their word that there's 12 strands in there. I was CONSTANTLY adding more and more strands to my ever-leaking nut wondering where they heck they were going.

I was surprised (and a little skeptical) of their choice of flax. They said that they've seen the graphite get hot and gouge the deepest grooves in shafts. They said the PTFE/Teflon stuff was what they used for a while but it got really really hard after a while and stopped working. They found that in the end flax was the most forgiving.

Now, with all that, how hot is too hot? I agree about using the thermal IR gun. I can borrow a crappy one, and have been needing an excuse to buy one. What temp is okay?

Also, I feel that all bets are off for the "standard rules of thumb" for how many drips per second/minute. If "X" number of drips keeps 4 strands cool, how many does it take to keep 12 cool?

Another piece of info, is that the stuffing box has never been hot before. I apparently had all kinds of crap mashed in there, (all the stuff I put in was teflon) and the shaft was wobbling around so much that maybe it never built up friction because it never fit, but it's never ever been hot before.

MedSailor

MedSailor 05-08-2013 01:00 AM

Re: Hot stuffing box...
 
Quote:

Originally Posted by JimsCAL (Post 1027052)
2-3 drips per SECOND!!! That's essentially a constant stream!...

Ummm... no it's not, it's fast dripping. Have you had your prostate examined recently? :D:p:D

MedSailor


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