Stuffing Box versus Dripless Shaft Seal? R29 Classic

[PuffinStuff]

Hello Fellow Tugnuts,

We are at the crossroads of a replacement of our existing system Last week while having the vessel serviced we requested the stuffing box packing be replaced. This led to us discovering when the boat was relaunched that we had a leak in the bilge compartment and significant water was entering. Nothing the pump couldn't keep up with. I expected some adjustments when underway, but noticed when I backed off the lock nut that it was NOT flush with the King Nut on the shaft. It has been put back on the shaft in a state of misalignment and cross-threaded the brass. We made it back to the marina fine and when the mechanic came back, things went downhill and the boat needed hauling again as the threads were so damaged once disassembled it could not be effectively reassembled in the water.

The choices are replace the existing traditional system or move to a dripless system. I am led to believe there is one from PYI and one from Tides Marine. I'm told the Tides system is preferable and more reliable. I have one fear of this system (DSS) which is sudden failure and potentially catastrophic water ingress, which seems unlikely in a traditional system.

Questions:

1. Has any Ranger owner had a dripless shaft seal system installed and what have been your experiences?
2. Is a fear of failure in this system realistic? Is there any real data to suggest they fail with any frequency?
3. If you have DSS systems in your tugs, which brands are preferred and why?

Thank you for any insights you might have. Timing is an issue here, as orders are set to take place tomorrow am.

Paul
Puffin
2012 R-29

 

[BradOwens]

We have a dripless shaft seal that was installed by the previous owner, or by Ranger Tugs at the owners request. I don't know the brand or model, but Andrew at Ranger Tugs could probably tell you. He sold us the boat and knew all the specifics. The boat is a 2012 and we have had no problems with the seal.

 

[PuffinStuff]

Thanks, Brad. Appreciate the feedback. Anyone else have some experience with these on their tugs?

 

[SmallChange]

I replaced a leaky stuffing box in my 25sc with a dripless PSS shaft seal two years ago and have been very happy with the results. Dozens of manufacturers of large and expensive boats use PSS systems as OEMs (see PSS website for list). I can't believe one would not have heard if there were a lot of failures.

Roger Phillippe

 

[10PoundHammer]

Two years ago after having the stuffing box adjusted 3 times in a year and running out of "room" for further adjustment I threw in the towel and had a PYI Inc PSS dripless shaft seal installed in my C30. Solved the problem and also the spray/mist that occurs with excessive dripping of the stuffing box. Works fine (~ 175 hours so far) and the mechanic tells me he has installed it in other Cutwater's/Rangers. Total cost (device, labour, misc parts etc) about Cdn $1,300 not including the haul-out. No doubt cheaper without the exchange rate.

 

[knotflying]

It seems like the problem is a bad mechanic. I got over 1,300 hours on my original packing and just replaced mine. The cost for the packing was chump change. Why reinvent the wheel because of an incompetent mechanic? I would work out a solution with the replacement cost of the original setup with the mechanic and stay with the old system. Then again, I like flooded batteries also 😀 Keep in mind, you were fine with the old setup until your mechanic screwed it up.

 

[10PoundHammer]

Except that I wasn't fine with the old set-up and the mechanic did exactly what I asked him to. So not sure how you leapt to "incompetent." When you live 1000 miles away from your boat and have little enough time to spend on it as it is, you value reliability. Seems like a least a few others, who don't have time or opportunity to spend as much time on their boats as they'd like, would agree. To each his own.

 

[Irish Mist]

I would say if the mechanic cross threaded the nut and it leaked that is pretty incompetent. IMHO

 

[NorthernFocus]

Don't miss the message in Mike's comments. Your problem was caused by the person who worked on it. Not by the equipment. The traditional stuffing box is a mature design that has stood the test of time . With modern packing materials they function extremely well. Dripless seals are less forgiving than traditional packing. I'd not place any bets on chance of success if you have the dripless system installed by the same people who cross-threaded your gland.

I repacked my stuffing box at the start of the 2016 season. The packing now has about 400 hours on it and is still fine. Modern packing materials can and will last indefinitely when properly installed and barring major misalignment of the drive train.

 

[PuffinStuff]

Roger that to all. I appreciate the feedback. I acknowledge that the stripping of the thread was the mistake of the mechanic who performed the work, but so does he. He has done great work before and came right down to our marina to make it right when he was informed what had happened. He gave us the option of him covering a new traditional system at his cost or putting in the dripless variety, with us just purchasing the seal. He's also covering the additional hauling costs and boat yard time. I think that is fairly stand up and appropriate. Anyone can cross a brass thread - s*&% happens. I agree with the time tested nature of the traditional stuffing box and relatively bullet-proof design, but we decided to go for the Tides Marine dripless shaft seal. This is a design that has also been around for years and years, with likely millions of cumulative hours. If there was a fatal flaw, I feel it would have been exposed by now. Given the continual maintenance the stuffing box has required over the last couple of years, I'm excited to be done with it.

Appreciate those who chimed in.

Paul
Puffin
2012 R-29

 

[NorthernFocus]

... Given the continual maintenance the stuffing box has required over the last couple of years, I'm excited to be done with it...

It might not be a bad idea to make sure your guy checks runnout on the shaft while he's in there installing the seal. One would like to think that's part of the seal install but I wouldn't take it for granted. If you were having that much trouble with your stuffing box there was/is something fundamentally wrong. It is possible that the packing was simply never properly installed from the beginning. If that's the case then the problem will go away with the new seal. However if the packing problems were due to running gear issues then you're not likely to be too happy with the new seal either unless you correct the root cause.

See step 5 in this article: http://www.powerandmotoryacht.com/refit-and-upgrade/maintaining-dripless-shaft-seals

 

[Arctic Knight]

Not on my Ranger but did have one on a sailboat some years ago. After 3 years it started to leak a bit just as I was leaving the Galapagos to return to Mexico. A 14 day run. I finally discovered that the problem was a buildup of mineral inside the flexible housing or gland ( a rubber fixture that looked like a bellows) that maintained pressure on the two faces that created the seal. The layer of mineral stiffened the gland so that it did not fully flex. The fix was to milk or kneed the flexible unit to break up the mineral build up and then pull the two faces apart to allow the mineral to escape with a flow of water. When released the flexible part resumed it job of holding the two faces of the seal in proper union.
I hope I have described this in an understandable manner.

 

[captstu]

I had a PSS dripless Seal installed on the 2010 R25 25 about twoyears ago.

The seal work perfectly with no difficulty.

Unfortunately both of the forward hose clamps holding the sealed to the Bellows failed. The clamps for the inexpensive stainless clamps have grooves cut in the stainless for threads. Both clamps broke at the bottom of the shaft blog where they could not be inspected easily because they were out of sight. In both cases the stainless was sitting in water because they're always a few drops of water in the very bottom where the shaft log goes through the hull.

Look at the video below for the results:

https://www.facebook.com/CaptStuj/posts ... 5040790069

 

[NorthernFocus]

...I hope I have described this in an understandable manner.

I understood it perfectly. But I worked on mechanical seals for a living 😀

Impressive troubleshooting and repair. Nicely done.