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Old 12-05-2021, 01:06 PM   #1
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"upgrade" to dripless shaft seals?

I'm doing some projects on my boat this Winter and have noticed that the hoses between between the packing glands and the prop shaft tubes are likely original and will be 30 years old next month. I was planning to replace them but was thinking this might be a great opportunity to switch to a dripless seal system while the shafts are pulled. I'd love to have a dry bilge while cruising...



What's a good system to use on a boat that's had packing glands for 30 years? I assume the shafts are not perfect so leaning toward PSS style.



Any reason not to use a dripless system?
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Old 12-05-2021, 01:46 PM   #2
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You will get lots of opinions on both sides. I like my PSS seal and had them on my charter boat for 15 years. I prefer it to the Tides system that came with my boat and is still on the rudder shaft. IMO, the wear surfaces are part of the PSS kit, as opposed to the shaft on the Tides kit.

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Old 12-05-2021, 01:51 PM   #3
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Quote:
Originally Posted by Mischief Managed View Post
I'm doing some projects on my boat this Winter and have noticed that the hoses between between the packing glands and the prop shaft tubes are likely original and will be 30 years old next month. I was planning to replace them but was thinking this might be a great opportunity to switch to a dripless seal system while the shafts are pulled. I'd love to have a dry bilge while cruising...
What's a good system to use on a boat that's had packing glands for 30 years? I assume the shafts are not perfect so leaning toward PSS style.
Any reason not to use a dripless system?
Tighten your present packing so that you have a dry bilge. If your packing is only 30 yrs old, it should be teflon impregnated, so will not score your shaft when tight enough to keep out the water. If you want to be sure, put new packing in. It may take a few short runs to get the packing properly tightened, but is a lot easier and less costly than changing to the so called "dripless".

You will also be saved from the possibility of a catastrophic failure, which, though rare, occurs enough that I personally know two boats that almost sank due to separation of the sealing surfaces on "dripless" setups. Think of your bilge pump capacity compared with the flow rate should those sealing surfaces be separated by only 1/4".
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Old 12-05-2021, 02:24 PM   #4
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In our last boat we used Duramax packing. It can gradually be tightened so that it does not leak and not damage the shaft. It takes about 5 to 10 hours of running before you should have it fully adjusted tight but then doesn’t leak.
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Old 12-05-2021, 04:21 PM   #5
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Agree with OC diver. I switched from Tides marine, which in my opinion has a very small sealing surface compared with PSS.
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Old 12-05-2021, 05:35 PM   #6
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Another vote for PSS. They have worked well for me for about 12 years on my present boat. I also put PSS seals on my rudder posts - access to the OEM packing glands was difficult.
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Old 12-06-2021, 07:28 AM   #7
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"What's a good system to use on a boat that's had packing glands for 30 years? I assume the shafts are not perfect so leaning toward PSS style."

Only change the packing , Duramax or similar.

"Any reason not to use a dripless system? "

Expense , complexity , and catastropic failure is possible.
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Old 12-06-2021, 09:29 AM   #8
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Quote:
Originally Posted by Mischief Managed View Post
I'm doing some projects on my boat this Winter and have noticed that the hoses between between the packing glands and the prop shaft tubes are likely original and will be 30 years old next month. I was planning to replace them but was thinking this might be a great opportunity to switch to a dripless seal system while the shafts are pulled. I'd love to have a dry bilge while cruising...

What's a good system to use on a boat that's had packing glands for 30 years? I assume the shafts are not perfect so leaning toward PSS style.

Any reason not to use a dripless system?
I was in the same boat a couple years ago. I decided to stay traditional packing gland as access to mine is excellent. As others have noted, with newer packing materials, a dry bilge is easy to achieve. I too would have opted for PSS vs Tides, though Tides has the option to install a spare seal on the shaft so if a replacement is ever needed, does not require removal of the shaft.

One item that is rarely discussed is the type of traditional stuffing box. My old one had the large single gland-nut that encircles the shaft (SIMILAR TO THIS). Over 45-years, the threads had worn/corroded and needed replacement. Plus required carrying a pair of giant wrenches that have zero utility elsewhere on my boat (except as a crude hammer I suppose). So I decided to go with the 'twin-ear' style with two smaller pressure nuts (SIMILAR TO THIS). Down-side to twin ear style is you have to be careful about keeping the nuts similarly compressed.

Bottom line, where access to the stuffing box is good, I would go with traditional style. Tried-and-true. If access is poor, I would definitely go with a dripless. I personally prefer PSS, but could live with others.

Peter
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Old 12-06-2021, 09:48 AM   #9
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"Any reason not to use a dripless system? "

Expense , complexity , and catastropic failure is possible.
Catastrophic failure is possible but very, very rare. The ones I'm familiar with were result of improper installation - failure to install the second of two set screws (the second sits atop the first one). Installing a hose clamp on the shaft resolves much of this risk. Not to say it carries the same risk of failure as a traditional stuffing box, but, in my opinion, the risk is greatly over-stated by the oft-cited risk of catastrophic failure. Impact is high, but probability is exceedingly low.

As far as cost and complexity, traditional bronze stuffing boxes with four SS T-Clamps is not exactly cheap either. I'd say the PSS is maybe 2x, so a few hundred dollars more.

Traditional stuffing box requires regular maintenance but is relatively easy to perform. PSS requires virtually no maintenance but when it does, will require the shaft to be pulled. I believe the recommended interval for bellows replacement is in the 7-year timeframe, though that appears to be conservative as many have been running the same bellows for 15+ years. I have never seen a recommended replacement interval for traditional hose, but my guess is it would be in the same range as PSS bellows, maybe less since PSS uses very high quality silicon hose which has a much longer life than the reinforced hose used in traditional stuffing boxes.

There are pluses and minuses to both. If access is good and you don't mind doing minor adjustments (especially if you're comfortable re-packing in the water, which is no big deal after you see it done once and realize not much water comes in), the traditional with modern packing is great. If access sucks or you hire-out even the smallest maintenance items, PSS is a good choice.

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Old 12-06-2021, 10:53 AM   #10
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Well, just in case you detect a consensus, I had PSS on my last boat and didn't like them at all. So switched back to Tides on current boat. I greatly prefer Tides.


It's true that you need a good shaft surface, so when retrofitting you will need to confirm that. But wear is negligible, and if it does become a problem all you need to do is slide the seal forward or aft a bit so it's riding on a clean surface.


What I don't like about PSS is that the pressure adjustment of the bellows can be very finicky, and changes over time as the bellows relaxes. I spent way more time that I'd like fussing with it to keep it from leaking. Also, the SS rotor that forms half of the sealing surface is prone to corrosion and pitting, and then it leaks. I found it to be a very fine line between leaking and overheating. When it worked it was great, but I think it's just way too touchy.


Tides just works. When the seal wears out, remove it and slide one of the replacements into place and you are back in business. Plus the hose cuff that holds it all in place is much more robust than the PSS bellows.
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Old 12-06-2021, 01:37 PM   #11
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Originally Posted by mvweebles View Post
Catastrophic failure is possible but very, very rare. The ones I'm familiar with were result of improper installation - failure to install the second of two set screws (the second sits atop the first one). Installing a hose clamp on the shaft resolves much of this risk. Not to say it carries the same risk of failure as a traditional stuffing box, but, in my opinion, the risk is greatly over-stated by the oft-cited risk of catastrophic failure. Impact is high, but probability is exceedingly low.


There are pluses and minuses to both. If access is good and you don't mind doing minor adjustments (especially if you're comfortable re-packing in the water, which is no big deal after you see it done once and realize not much water comes in), the traditional with modern packing is great. If access sucks or you hire-out even the smallest maintenance items, PSS is a good choice.

Peter
You make a good argument for old style, traditional seals.

One catastrophic failure on a boat that I know, was a sailboat that had a rag drop into the bilge and get caught up in the spinning shaft at the gland, destroying the seal and causing the panic of a stream of water far beyond the capability of the resident bilge pump. Nothing to do with installation problems. This boat has a Very finicky owner.
The other was a GB42 that hit a log and when the extent of flooding was known, drove up on the beach pending recovery. Again, nothing to do with installation. An equally finicky owner.

If access sucks, recovery from a catastrophic failure with a "dripless" will not be easy. Such difficult access would militate against that type of seal.
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Old 12-06-2021, 02:04 PM   #12
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The dripless seal may not be an “up grade”.

They are good .. but? I had one on Willy. But if I had it to do over I’d go w the packing gland seal. They leak very little and what boat is not equipped to pump water? Just change the packing when you haul out. And keep it adjusted properly.

I don’t see the need for no leak at all. Maybe some to many are afraid of the word “leak” ? Boats aren't/wern’t made out of Walnut because they made Caskets with Walnut.
So perhaps a seal that dos’t “leak” is in a “gotta have it” category?

But I had a PSS and had next to no problems. I now remember you’re supposed to burp the seal wet for lubrication or/cleaning of the surface or ?. I even forgot that .. but no leakage.
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Old 12-06-2021, 02:05 PM   #13
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You talked about replacing the hose and I would put that high on your list. When I purchased my boat, it had a torn stuffing box mounting hose that was 35+ years old and it was a fairly serious situation. Buck Algonquin makes hose specifically for this job, it makes exhaust hose look thin.
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Old 12-06-2021, 03:15 PM   #14
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You make a good argument for old style, traditional seals.

One catastrophic failure on a boat that I know, was a sailboat that had a rag drop into the bilge and get caught up in the spinning shaft at the gland, destroying the seal and causing the panic of a stream of water far beyond the capability of the resident bilge pump. Nothing to do with installation problems. This boat has a Very finicky owner.
The other was a GB42 that hit a log and when the extent of flooding was known, drove up on the beach pending recovery. Again, nothing to do with installation. An equally finicky owner.

If access sucks, recovery from a catastrophic failure with a "dripless" will not be easy. Such difficult access would militate against that type of seal.
Yes, those are the types of "Meteorite Strike" events that for me, lean-towards a traditional stuffing box where access is easy. But the risk for inaccessible access is great - they rarely get serviced properly, rarely re-packed, and rarely replaced. Very high liklihood of scored shaft. An owner of a Camano 31 recently posted pictures of his that looked positively inaccessible. I had a Willard 30 Searcher model where access was poor. I once looked at at Crealock 30 traditional with a V-Drive that required a mirror to even see the stuffing box. I would take my chances with very low probability of a catastrophic failure, or perhaps a lip-seal style such as Tides might make more sense.

I have personally experienced a failure. I was living aboard when a friend on his Brewer 46 PH sailboat arrived a few slips down. He pops-up through his campionway and starts yelling for me as if a hyena chomped-down on his naughty-bits. I run over an his engine hatch is open with a gusher coming in. It took me a few seconds to comprehend, but I waded down and quickly discovered the PSS rotor had backed-off. I held it in place while my buddy fetched a hose clamp. We retrieved the set-screw from the bilge and got it squared away.

I'm not naive about the issues with a dripless shaft. It's a tradeoff. There are many mild ways for a traditional box to go wonky, though catastrophic is extremely rare. Relatively modest likelihood of some sort of damage (scored shaft, broken casting, etc), but low impact too. But risk increases if not properly maintained, so your risk on both levels increases (probability and impact). With dripless, very low likelihood but higher impact. Pick your poison. If you're not the type to maintain your stuffing box, or access is poor, there's a strong argument for dripless.

Peter
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Old 12-06-2021, 03:33 PM   #15
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Absolutely do not use exhaust hose for a stuffing box, they make special hose for that application that resists the twisting forces.
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Old 12-07-2021, 07:20 AM   #16
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One of the big advantages of a modern packing like Duramax is with care no dripping at all is easy.

The advantage is in shallow water sand and debris does not enter with the dripping water.

The debris is frequently pressed into the packing where it becomes a wear source on the shaft , that's where the groves on the shaft come from.
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Old 12-07-2021, 10:44 AM   #17
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i used pss seals on two of my last boats and loved them. one lasted more than 20 years and was still holding. i changed it out only due to the age of it. i added one to my steel boat so i could keep the bilge dry. perfect application for that one. if you're worried about debris creeping in, you can plumb the raw water into it to flush the seal. high speed installations require that too.
my new to me boat has a conventional gland and i'll probably leave it. it's a glass hull and the bilge can handle the small amount of water that gets in.
just do what makes sense to you, i don't think either way is bad, just different.
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Old 12-08-2021, 10:59 AM   #18
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Like others have said, PSS (or similar mechanical seals) work well if properly installed and properly maintained. The problem is there's a few things that can go wrong with them. The bellow can loose compression (causing a bad leak), the rotating face plate can slide forward on the shaft (causing a bad leak), the carbon stator sealing face can crack (causing a bad leak), the rubber bellows can rip/tear. You get the idea. I've also seen shafts fail around the set screw indentations required to install the PSS style.

You might just be able to replace the packing in your existing boxes with Duramax Ultra-X. If you're looking for something a little more robust with the benefits of a dripless system and but the reliability of a heavy duty bronze system, check out the self-aligning shaft seals by RE Thomas.

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Old 12-08-2021, 12:31 PM   #19
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Like others have said, PSS (or similar mechanical seals) work well if properly installed and properly maintained. The problem is there's a few things that can go wrong with them. The bellow can loose compression (causing a bad leak), the rotating face plate can slide forward on the shaft (causing a bad leak), the carbon stator sealing face can crack (causing a bad leak), the rubber bellows can rip/tear. You get the idea. I've also seen shafts fail around the set screw indentations required to install the PSS style.

You might just be able to replace the packing in your existing boxes with Duramax Ultra-X. If you're looking for something a little more robust with the benefits of a dripless system and but the reliability of a heavy duty bronze system, check out the self-aligning shaft seals by RE Thomas.

this just looks like a water fed stuffing box. nicely made for sure, but what's the advantage?
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Old 12-08-2021, 07:59 PM   #20
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this just looks like a water fed stuffing box. nicely made for sure, but what's the advantage?
We have a downeast style lobster boat (Calvin Beal) single diesel inboard engine. These self aligning seals are standard equipment on these types of boats that get 1500 to 2000 hours per year (not ours, but the boats used as commercial fishing boats). With the water feed, you’re able to tighten the packing nut so you don’t need the drip drip to keep the packing cool. You’re able to have the benefits of a “dripless” seal, with the reliability of a traditional bronze stuffing box. They’re not for everyone, and they cost more, but they are more reliable and require less maintenance. And they’re not as prone to catastrophic failure as others have mentioned.
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