Shaft Alignment - CD30, Volvo MD7A

[mgphl52]

John & Jean
Yep! Those are all the reasons I replaced the drip-less on KAYLA with a bronze stuffing box. I was lucky to have a friend doing the opposite on his CD25D and gave me his stuffing box.

[ghockaday]

David
I originally thought I might install a PSS. But I started running across a number of horror stories. Sure, some people seem to love them but plenty of folks have gone back to traditional stuffing box after suffering significant failures. Maybe they weren’t installed correctly.

I have turned away for the PSS dripless and gone with a traditional bronze stuffing box and plan to use goretex or graphite stuffing. Apparently that’s what’s they are using in the USCG...or so I have read. I have also read there is practically no water drips with graphite or gore stuffing. I’ll know more about it after a couple years use.

I have a couple issues with the PSS. The first is its expensive. When maintenance is performed as recommended by the manufacturer it get even more expensive—bellows replacement every six years. Another thing, for me, sailing offshore, if I have a leaky stuffing box I can tighten it. I can wrap the packing nut with waterproof tape. I believe I could stay ahead of any leaks. But if a PSS bellows tears badly it’s going to be a whole lot harder to stop the flow of water. And if I’m hundreds of miles offshore that would be a real problem. You can change flax out with the boat in the water if you had too. If you suffer a bellows tear the boat has to come out of the water and quickly I would think.

Here is an interesting link on things to watch out for. https://waggonerguide.com/dripless-shaf ... ance-free/

Clearly, there are some, maybe even many, sailors that are very happy with them and swear they work great. Over on Sailing Anarchy, a place I normally avoid, there are some interesting threads on the dripless boxes. Folks will say they love them but then go on to say “except for that time when the bellows failed and we nearly sank....”.

But here is the thing, be wary of falling into the trap of treating the symptom. If you have a shaft engine miss-alignment, installing a dripless stuffing box is not going to correct the problem. What you are going to end up with is a worn out shaft log bearing and trouble with the Dripless seal. Any misalignment is going to eventually cause problems. I’d recommend you start with the bearing shaft alignment. Then consider a flexible coupling. Then get a dripless seal if you want.

I recall reading some positive info on the PSS on mainsails site (AKA Marine How To). He seems pretty competent and reasonable. You might find some good info there to help you decide.

I’d also ask Jim W and Steve L for their thoughts. They are both a couple smart experienced sailors.

Happy sailing.

John, I have used the Goretex brand PTFE impregnated packing and I haven't seen a drip in two years. I have tried to loosen it to get it to drip and it won't and backed it out as far as I dare. Once sealed it seems stays sealed. I could only get 3 rings to fit. It looks like it sweats a bit. I did not like the grease and flax packing. I changed when I went to a alloy shaft. So when I haul out I am going to inspect the shaft for ware and if there is none I'll keep using it. Dennis

[S/V Ethan Grey]

Thanks again everyone.

Reading through the manual, I learned that there are a couple of ways CD decided to do the shaft log. It seems that the CD28 has a bolt through shaft log/stuffing box combination whereas the CD30 (mine at least) has a solid fiberglass tube as the shaft log and an independent stuffing box (packing gland) that attached to the shaft log with dual clamps.

At this time, I have too many other things to fix $$$ to convert to PSS, so I plan to stick to the traditional stuffing box but convert to gore packing.

Looking at the coupling between the propeller shaft and transmission, the bolt holes on the propeller coupling are augured out. So, it looks like I’ll need to replace the coupling. This may result in having to get a new propeller shaft as well. I’ve heard the couplings are terribly hard to remove and many people just cut their shaft in half to remove. I currently have a SS one, so it has been changed at some point.

With the propeller shaft and stuffing box removed, I might be able to squeeze behind the engine to figure out where the leak is coming from. Good times. Unfortunately there isn’t a do-it-yourself yard around here and I can’t bring the boat home to work on it.

Nothing a bucket full of cash, or two, won’t cure I’m sure.

[ghockaday]

Regarding graphite, the quote below is why I did not go with it.

Graphite Extruded Teflon – These products usually have the graphite lube physically extruded into the Teflon yarn before it is braided. Extruding the lubricant (graphite), mixed into the yarn, is a far superior process than “impregnating” the product after the extrusion & braiding process. This material offers the best heat transfer due to graphite’s inherent ability to transfer heat rapidly. The addition of graphite, as the performance lubrication, allows for minimal dripping and longer times between adjustments. The down side to graphite impregnated packing’s is that graphite is the most noble element on the galvanic scale. In other words graphite packing materials can cause localized damage to shafting and can increase anode erosion rates. The ABYC and Western Branch Metals (The largest prop shafting manufacturer in the US) specifically disallow the use of graphite packing materials. With the great performance come some cautions and risks.

[mgphl52]

Regarding graphite, the quote below is why I did not go with it.

Great info! Thanks for posting.

[Frenchy]

Don't confuse PTFE/graphite packing with GFO packing, the one the Coast Guard uses. The GFO is the one you want. - Jean




http://gfopacking.com/

[John Stone]

Don't confuse PTFE/graphite packing with GFO packing, the one the Coast Guard uses. The GFO is the one you want. - Jean

http://gfopacking.com/

You are right about that Jean. I remember reading about the potential problems with graphite versus GFO. Thanks for the reminder. I’m actually getting close enough to start thinking about it.

[ghockaday]

Don't confuse PTFE/graphite packing with GFO packing, the one the Coast Guard uses. The GFO is the one you want. - Jean

http://gfopacking.com/

You are right about that Jean. I remember reading about the potential problems with graphite versus GFO. Thanks for the reminder. I’m actually getting close enough to start thinking about it.

So what makes the difference, I tried finding out what it actually was and it was kind of like saying "GFO is GFO" Its made with GFO.

If I went down the correct rabbit hole at the Gore site, it is made with ePTFE? e being expanded. So if it is still PTFE and it is infused with graphite, what is the difference. Kind of mysterious. I'll continue to look and inquiring minds want to know. Dennis

This is what I found a McMaster-Carr for their packing.
Also known as 100% GFO, these expanded PTFE seals contain graphite powder, which dissipates heat away from the shaft and allows pumps to run cool at high speeds. Use them in applications involving acids, alkalies, brines, and solvents. Cut these seals to size with a knife; then pack them into place.

[Frenchy]

That's interesting- you may be right that the GFO packing has graphite infused fibers - I don't know. Their website claims
no shaft wear and there are probably thousands of users who agree. It's also claimed that the GFO packing doesn't need
water flowing through it as a conventional packing does. I leave the packing nut hand tight-no wrenches- and there are no
drips.
I've used it for a long time and am satisfied. No problems. - Jean

[ghockaday]

That's interesting- you may be right that the GFO packing has graphite infused fibers - I don't know. Their website claims
no shaft wear and there are probably thousands of users who agree. It's also claimed that the GFO packing doesn't need
water flowing through it as a conventional packing does. I leave the packing nut hand tight-no wrenches- and there are no
drips.
I've used it for a long time and am satisfied. No problems. - Jean

That was the thing with the high speed ptfe backing that I used, It can't be much over hand tight and does not drip. I was concerned that I had it too tight but if I make it any looser I feel like the nut could vibrate off. I love the dry bilge.

Since yours is the same way and you haven't had an issue it makes me feel better about how loose I keep mine and get no trips. I may change to the GFO as I liked the thoughts of very low heat. Dennis

[Paul D.]

I too am a fan of the Spartan bronze packing gland arrangement. Not too much maintenance and once you do it once, while never completely easy, it is not a big deal to maintain and can always be sorted out if a problem. Spartan makes a good one too.