stuffing box concerns

orientalnc2010 · #1 08-16-2009

Hey all,
Before I start with my concern, I have read a great deal about stuffing boxes and have successfully repacked several stuffing boxes on various boat I have owned. My previous boats had the shaft supported on the outside of the boat with a strut and cutlass bearing within.
This is the first time I have dealt with the setup that Pacific Seacraft has, this arrangement is nothing new in the marine industry but new to me.
Since the lubricating water has to get past the cutlass to get to the stuffing box do they have a tendency to run a bit warmer? I have read that stuffing boxes should be cool and never exceed 20 greater than the water temp. This is subject to opinion and I do not mean to open the debate,but we all argee that they should never run hot.
Does anyone have a box that runs warm? Since my boat only has 25 hours on her I assume mine is warm

(enough to be concerned) due to the cutlass being so new.
The drip rate is 3 per min underway with an occasional drip at rest, the packing is hand tight and wrenches are only used to tighten the lock nut against the packing nut and not the other way around. I tried increasing the drip rate to 12+ per min and she is still warm????

Norstar · #2 08-17-2009

Steve,
I just adjusted ours this past weekend and have it about 2-3 drips per minute. This is probably a little less then normally recomended but I tend to run ours a little tight. The shaft log runs about the same as water temp which is cool to the touch after running at 2500 rpm for an extended time. Maybe on the 31 the distance from the rear of the coupling to the shaft log is a little shorter and your picking up some heat transfer from the transmission?
As long as your shaft log is not getting hot, I would say your ok. Some will argue that you should have more drips per minute but I like to keep the bilge as dry as possible. I keep a large sponge under the log so it contains the water on most short trips to the inlet. When the boat is not running the drip just about stops. The result is a dry bilge for the most part.

John S.
PSC 34 # 201
"Norstar"
sailnorstar.com

lsbrodsky · #3 08-17-2009

Steve,

I doubt the age of the cutless has anything to do with it. I ran my 31 with the standard box for about a year with 5-10 drip and the box never got overly warm. Then I went to the teflon packing and goo where the recommended drip was zero. Again, it never seemed overly warm. I replaced that with a PSS after about 3 years and everything felt about the same. I would suggest that the best test is to see whether you are damaging the packing at all, if not, and you have the right drip rate, then I would not worry.

Larry

JohnRPollard · #4 08-17-2009

Adding to what John and Larry report above, we get 2-4 drips/minute underway, and almost none when static. I have noticed some warmth at the stuffing box but never enough that it worried me. We don't motor a whole lot.

Pamlicotraveler · #5 08-17-2009

I adjusted mine this weekend and can say the goal of getting 3-4 drips a minute is most elusive. By the time I tighten the locking nut it changes...

orientalnc2010 · #6 08-17-2009

Hi John and y'all down in NC were I long to be,
My stuffing box has decided to run hot to the touch, I suspected that it might get worse so I had all the materials on hand to repack the box.
The manual from PSC listed the flax as 3/16 for the 31 as well as the 34 & 37.
I did bring along some 1/4" just for in case. Good thing I did as the packing I removed was 1/4" and the 3/16 was obviously to small. I think they call it a "stuffing box" because the flax should not just fall into the packing nut. The 1/4 was a nice tight fit that needed to be gently pushed home with a wooden dowel.
The flax I removed appeared to be in OK shape, it was not brittle but its difficult to tell how much lubricant was cooked out. There had been, from time to time, a bit of greenish water dripping from the box which I now believe to have been lubricant.
After I finshed, I did not have time to take her for a good work out but I did keep her in gear at 2400RPM on the mooring for 10mins and all seemed to be good. I did use the Pacific Trading PTFE flax and it was nice a juicy, I also applied a generous amount of their PTFE packing lubricant to reduce friction.
This weekend I will give her a good motoring and see what happens.
It's a bit of a puzzle why after only 25 hours she decided to get hot even though she had been dripping fine, could be engine alignment but vibration is minimal. Perhaps the factory packing "dried up" as she was built in 07 commisioned in 09?

orientalnc2010 · #7 08-23-2009

After several hours of motoring this weekend it seems as though my hot stuffing box is now running at normal temp. I have never work on a stuffing box that is so accessible. I will admit I was apprehensive about repacking a stuffing box with the boat in the water, after doing the job I would not hesitate to do it again.

billbalme · #8 08-24-2009

The whole stuffing box thing scares me...

With the stuffing removed, what prevents water gushing in when replacing the flax with the boat in the water?

Since mine is now dribbling as opposed to dripping, I need to attend to it - and hopefully cure the transmission noise (wishful thinking)... I'm hoping that I'll be able to stem the tide with a tightening, rather than have to re-pack it - though Steve's experience is certainly encouraging...

Bill

lsbrodsky · #9 08-24-2009

Bill,

I would not be afraid of it; it is not like it is a 1 inch hole in the water. The leakage path is along the shaft around the cutless bearing. That is not enough leakage to interfere with packing the stuffing box. You would not want that much leakage unattended, but repacking in the water is a normal task.

Larry

orientalnc2010 · #10 08-24-2009

Hi Bill,
Larry's right about the amount of water entering the boat, I was preparing myself for more. To take make the job less stressful I took electrical rubber insulating tape and wrapped it around the shaft and stuffing box. If you haven't used this stuff before it's available at Lowes or Depot, it does not have any adhesive but sticks to itself much like rigging tape. At 3 bucks a roll it's a bargain. After a couple of wraps the amount of water entering the boat was zero. This allowed me to take my time packing the flax which I had already pre-cut.Then peel the rubber off, which leaves no residue, and calmly thread the nut back on the threads.
If you screw it up somehow, just reapply the rubber tape and it will keep the water out of the bilge until you get things sorted out.