Standard stuffing box vs. PSS seals vs. "self aligning" gland

[Patches]

Interesting, the concern about the PSS bellows.  It seems to me a pretty rugged piece of hose.  What is the the failure mechanism which concerns those about the PSS bellows, but not regular stuffing box hose?  Is it that something will come in contact with the PSS bellows which will cause it to fail, because it isn't as "thick" as regular stuffing box hose?

Not sure I understand.  I do understand the concern about the rotor backing off, relaxing the bellows, and allowing water ingress.  What am I missing?

And WBev:  why would having a keel stepped mast vs. a deck stepped mast cause you to choose one over the other?  That one stumps me too.

Patches

[Noah]

Patches—my "fear of bellows failure" is NOT based upon any firsthand knowledge of any failures. It is just my vibe that it seems more exposed, is a lighter material, more complicated a set-up and more vulnerable to failure than the traditional stuffing box system. As far as deck step vs keel step: I think what he was getting at was if your goal for having dripless was a "dry bilge"; if you have a keel step mast you will have water coming into the bilge via the mast so the goal of a dry bilge is more difficult to maintain. Albeit water coming down the mast would be fresh water.

[WBev]

Patches - Noah nailed it.  The Pearson is dry as a bone, so the PSS keeps it that way.  While fresh water from the mast is better than salty (Chesapeake Bay) water, the dampness is not prevented and the "bang for your buck" diminishes.  That is the main reason why I chose not to install the PSS. 

The rubber boot on PSS is light, and is much thinner than the standard tunnel rubber. It is pliable and quite strong.  I knocked into it many times dealing with other issues on the Pearson, including with the pointy end of a wire hanger I had to put in to keep a hose off of it during a week long trip.  The real issue I see is if the PSS bellows tears, by its very nature it will likely allow a lot more water in than a standard stuffing tube will.  It is made to fill with water and does so fairly quickly.  A good rag or something might slow it down some, but it does seem like it would allow swift ingress.  (While waiting to be lifted, I did push the bellows aft, separating the seal, and a lot of water came in. This was intentional, purely my curiosity, and the boat was in the slings.)

[Trillium]

Interesting conversations around the stern gland wear.

One aspect that should be considered is cutlass bearing wear and what the total alignment is through the cutlass bearing, stern tube and gland and coupling. I have just changed my cutlass bearing and noted that the shaft is not concentric in the P bracket, as indicated by the collets on the removal rig.  I studied the old bearing, as I have with numerous journal bearings on large rotating equipment units to determine the shaft alignment, and determined that it appears to have been running in the 11 o'clock position and that there was no rubber left in that area of the old bearing.  The new bearing is also compressed more in the same position indicating a lack of concentricity.  I have checked the coupling alignment in the past and repacked the stuffing box; but now I have the opportunity to split the coupling and after checking the shaft "journal" area for wear, check whether the shaft has changed its position within the cutlass bearing having been released from the engine coupling.

I would have thought that the problems with the stuffing box may arise from either coupling misalignment or a cutlass bearing/bracket problem since the stuffing box should float on the shaft.  If there is damage to your stuffing box gland it may be a symptom of problems elsewhere rather than being part of a root cause, in which case it may pay to look further rather than just change the type of seal.

Nigel
Trillium 2004 Catalina Mk II #1683

[tmac]

I'm certainly no expert on this problem, but as I was reading through this discussion the thought occurred that you might check to see whether the strut that holds the cutlass bearing has ever been bent (however slightly).  Could have been from a slight grounding, or maybe by a boatyard accident as it was being placed in a cradle.  Since you've already eliminated the more common issues, you may have to look at the more unusual...

[Breakin Away]

Unfortunately it is time to re-awaken the thread. The mechanic who was supposed to fix this problem for me didn't show up all winter, and I just learned that he was terminated and banned from doing any freelance work in the boatyard. I don't know why this happened, but I'm forced to start over again for the third time. This was my second mechanic - mechanic #1 was fired by me last October because he showed up for the job 90 minutes late and smelling of alcohol. So between me and the marina, we're burning through mechanics pretty fast.

I'm glad this thread is here so I can re-read it to refresh myself on my thinking as I reconsider whether to do this myself or find mechanic #3 and hope he shows up during peak commissioning season. I am SO FRUSTRATED because this is exactly the situation I meant to avoid by contacting mechanic #2 last October. I selected this boatyard exclusively because this mechanic worked there, and they had told me, "Sure, bring your boat here for the winter since he does all his work here."

Some other comments:

The cutlass bearing looks great - perfectly even wear, and it's only 3 years old. The shaft rotates freely by hand with no tight spots, which the mechanics said means that everything is in alignment. The stuffing box was replaced in early 2019, along with the shaft (Aquamet G22 upgrade), strut, cutlass bearing, prop, and coupler. I have inspected the old stuffing box and shaft that were removed at the time, and can see wear patterns that suggest that this issue may have been present (and undetected) for quite awhile before 2019. The nut on the old stuffing box is "polished" at the 2 o'clock point, and the inside of the insert that the nut screws into is polished at the 8 o'clock point (180° opposite). The shaft appears to enter the shaft log well centered. So my working hypothesis is that the stuffing box is inserted slightly crooked into the rubber hose, or that the hose itself is very slightly crooked. There is very little tolerance in the alignment, since the nut and stuffing box insert are 1.02" diameter. So if the stuffing box assembly is off by 0.01" at either or both ends, the packing could wear unevenly until the shaft contacts the nut at the fore end of the stuffing box, and/or the aft end of the insert could contact the shaft.

Last season, while the boat was still in the water, I loosened the stuffing box and "clocked" it 180°, hoping that moving it around a bit would allow it to re-center. That did not work. I then loosened the clamps at the aft end of the hose, and tried to clock it, but it was too tight and I didn't want to use any tools on it for fear of shredding or breaking something, which could be catastrophic with the boat in the water. Mechanic #2 was supposed to do this while the boat was on the hard this winter, but he's out of the picture now.

Since the boat is 21 years old, I am thinking I should consider replacing the hose. (I should have had them do that in 2019 when they had the shaft out.) Catalina Direct has thin wall and thick wall versions:

https://www.catalinadirect.com/shop-by-boat/catalina-38/engine/props-etc/stuffing-box-hose-kitw-clamps-1-58quot-id/
https://www.catalinadirect.com/shop-by-boat/catalina-30/engine/props-etc/stuffing-box-hd-hose-kitw-clamps-1-58quot-id/

Do you have any comments on the amount of clearance between the shaft log and the hull underneath? Maybe the thin walled version might have a little more "flex" that could allow the stuffing box to align with the shaft better. Either one looks to be significantly beefier than the bellows in a PSS seal. (I will check to see which thickness my boat currently has.)

Also, if I do this replacement I need to separate the shaft from the coupler. Since both are only 3 years old, I'm hoping they are not too badly corroded together. I'll shoot some PB Blaster into it tomorrow and hope that helps. Do any of you have comments on the shaft puller that Catalina Direct sells?

https://www.catalinadirect.com/shop-by-boat/catalina-28/engine/maintenance/coupler-puller-yanmar-amp-universal-diesel/

[Kyle Ewing]

I use a steering wheel puller (something like https://shop.advanceautoparts.com/p/performance-tool-steering-wheel-puller-w150/11963067-P) to push the shaft out of the coupler.  I shortened the long center pushing screw due to clearance.

Here's an article on engine alignment that helped me.  https://www.yachtsurvey.com/Alignment2.htm

My approach to final alignment in the water was by making many tiny changes until I was happy with the level of vibration.  I'd run the engine in gear, make a change (write it down in caseI needed to reverse it) then test again.  I did this based on the idea from the article that the system is "floating" and alignment changes when in gear.

How much stuffing box flax do you use?

To eliminate all causes, you could pull the shaft and prop and have a shop confirm everything is balanced and nothing is bent.

[girmann]

I think that, at this point, you don't really know what's true from mechanic #1 or #2. It's possible one or both were somehow incompetent or unqualified. Start with a new mechanic and only describe the symptoms. You may have to go backwards to go forwards.