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  #31  
Old 08-31-2012
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Re: Dripless Shaft Seal versus Stuffing Box

Well I know what i am going to be checking out this weekend . Thanks Maine.
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  #32  
Old 09-04-2012
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Re: Dripless Shaft Seal versus Stuffing Box

Quote:
Originally Posted by Maine Sail View Post
I would suspect Catalina moved back to a traditional stuffing box because they are about 1/3 the cost of a PSS (based on wholesale pricing and Catalina pays less than I do I am sure).

The installation is also less costly for Catalina with a traditional gland not having to run an extra hose for the vent.

The PSS seals are extremely reliable and are used by the USCG and the world best builders. I know of some in commercial used with over 10k hours on them.

All the failures of PSS I have read of have been due to installer or owner error. The stainless rotors do not slip if properly & competently installed. I have seen 20 year old PSS seals still working perfectly. I have one customer who still has the old cloth covered bellows, this despite my very strong suggestion he replace it. I don't think PYI has made those bellows for about 15-20 years.

The term "properly installed" means the grub/set screws that contact the shaft are only ever tightened once. ONCE!!!! Tightened and used are two different things. They also need to be tightened to the proper torque with the proper Allen key.. PSS ships the proper Allen key but I still see grub screws molested by using the wrong Allen key.

Often times installers mess up the adjustment or compression of the bellows. Sadly they think nothing of loosening the set screws and simply moving or re-adjusting the rotor and snugging up the set screws. PLEASE DO NOT DO THIS! If this is done it is no longer a proper installation and you have just increased the risk of the rotor slipping and a leak. If you need to adjust the bellows you need to use brand new set screws.

These set screws can only be tightened once because the shaft, usually Aqualoy or Nitronic, is harder than the grub screw. These volcano head screws rely on the initial "cut" or bite into the shaft for the grip. Loosen the screw and move the rotor, even 1/8" and you need new screws.

PYI Says this right in the installation instructions:

"Do not re-use the supplied cupped pointed sets screws."

What is a one time use? If you tighten the set screws onto the shaft even once, that is your use. For example if you are installing the PSS and adjust it, tighten the set screw then realize the adjustment was wrong you now need to use new set screws. This is installer error numero-uno with PSS seals....


For years I have installed PSS seals with "clamp collars" from McMaster Carr as added insurance. Hose clamps and zincs are really not the ideal solution but a clamp collar is designed for this:


Here's a better view:


PYI saw me using these and they now offer their own "clamp collars". IMHO all PSS seals should come standard with a clamp collar, and a bag of extra set screws, but I digress. It would virtually eliminate installer error and slipping rotors and help eliminate the "I had a PSS failure" threads, which were really "installer error".

Both standard glands and PSS seals are reliable. I have however seen and know of plenty of sinkings related to traditional boxes. They are also highly prone to installer or user error. Hoses on traditional boxes also need to be changed so a traditional gland is not immune from hose replacement maintenance.


Despite misleading marketing messages by packing manufacturers traditional boxes should not be run "dry" or "dripless" but they can be "drips-less" than older plant based packings.. They, all PSS type or traditional glands, need to pass some water (traditional) or vent air (PSS type), or they can overheat. Trapped air or not passing of water can also lead to stagnation and corrosion of the shafting up inside the log.

This is what stagnant water on a traditional box set to not drip can do:


Some boats are more prone to trapped air in the log hence PYI's move to all vented/plumbed seals even on slow moving craft. "Burping" on some boats was more than just at launch time so vents make a lot of sense on all sailboats.

Newer packings can be pretty darn drips-less but should not be 100% dripless. it can be so minimal that engine warmth evaporates any drips before it accumulates.

Unfortunately I can't count the number of times an owner or yard mechanic has said to me "Yeah when I adjusted the PSS." and I ask "Did you replace the set screws?" and am treated with a blank stare? Scary stuff!

If a failure were to occur with a slipping rotor, in this scenario, it is installer error not the fault of PYI or the PSS seal.

I also very often see the vent holes plugged with brass or ss plugs. The vents should always be plumbed (power) or vented/used on sailboats. Metallic plugs should never, ever be used in the carbon rotor. There is a reason PYI uses a nylon hose barb and that is because the carbon is the most noble element in the galvanic scale and the differing expansion contraction characteristics between brass or SS and the carbon...

PYI says this in the instructions but many people choose not to read or heed them:

"Do not tighten or replace the installed nylon hose barb fitting with a metallic fitting (bronze or stainless steel). Metal hose barbs will damage the carbon and destroy the PSS."

Again, this type of failure, overheating of the seal, dissimilar metals corrosion or a split carbon would clearly get blamed on the PSS seal. Sadly on the "net" PSS takes the hit not the dolt who caused the failure by not following the installation instructions. These are examples of installer error not a failure on the part of the seal. I see the metallic plugs and set screw errors frequently.
MainSail:
Why do you have those perforated hose clamps on the PSS bellows? My understanding is they are not recommended due to accelerated corrosion factors.
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  #33  
Old 09-04-2012
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Re: Dripless Shaft Seal versus Stuffing Box

I never felt safe leaving my boat with the PSS type sea, as anything falling on it would quickly sink the boat. The most a stuffing box will do is drip slowly. So I went back to my stuffing box and regained much peace of mind.
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Re: Dripless Shaft Seal versus Stuffing Box

I use the orthodox stuffing box on my Polaris 36, and have for the last 20 years.
Last time I changed the packing on it was 15 years ago.
It is reliable, orthodox and cheap to maintain. It really has never given trouble. It drips a bit, but I live with that, as other owners have since the beginning of steam power.
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  #35  
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Re: Dripless Shaft Seal versus Stuffing Box

Quote:
Originally Posted by Maine Sail View Post
I would suspect Catalina moved back to a traditional stuffing box because they are about 1/3 the cost of a PSS (based on wholesale pricing and Catalina pays less than I do I am sure).

The installation is also less costly for Catalina with a traditional gland not having to run an extra hose for the vent.

The PSS seals are extremely reliable and are used by the USCG and the world best builders. I know of some in commercial used with over 10k hours on them.

All the failures of PSS I have read of have been due to installer or owner error. The stainless rotors do not slip if properly & competently installed. I have seen 20 year old PSS seals still working perfectly. I have one customer who still has the old cloth covered bellows, this despite my very strong suggestion he replace it. I don't think PYI has made those bellows for about 15-20 years.

The term "properly installed" means the grub/set screws that contact the shaft are only ever tightened once. ONCE!!!! Tightened and used are two different things. They also need to be tightened to the proper torque with the proper Allen key.. PSS ships the proper Allen key but I still see grub screws molested by using the wrong Allen key.

Often times installers mess up the adjustment or compression of the bellows. Sadly they think nothing of loosening the set screws and simply moving or re-adjusting the rotor and snugging up the set screws. PLEASE DO NOT DO THIS! If this is done it is no longer a proper installation and you have just increased the risk of the rotor slipping and a leak. If you need to adjust the bellows you need to use brand new set screws.

These set screws can only be tightened once because the shaft, usually Aqualoy or Nitronic, is harder than the grub screw. These volcano head screws rely on the initial "cut" or bite into the shaft for the grip. Loosen the screw and move the rotor, even 1/8" and you need new screws.

PYI Says this right in the installation instructions:

"Do not re-use the supplied cupped pointed sets screws."

What is a one time use? If you tighten the set screws onto the shaft even once, that is your use. For example if you are installing the PSS and adjust it, tighten the set screw then realize the adjustment was wrong you now need to use new set screws. This is installer error numero-uno with PSS seals....


For years I have installed PSS seals with "clamp collars" from McMaster Carr as added insurance. Hose clamps and zincs are really not the ideal solution but a clamp collar is designed for this:


Here's a better view:


PYI saw me using these and they now offer their own "clamp collars". IMHO all PSS seals should come standard with a clamp collar, and a bag of extra set screws, but I digress. It would virtually eliminate installer error and slipping rotors and help eliminate the "I had a PSS failure" threads, which were really "installer error".

Both standard glands and PSS seals are reliable. I have however seen and know of plenty of sinkings related to traditional boxes. They are also highly prone to installer or user error. Hoses on traditional boxes also need to be changed so a traditional gland is not immune from hose replacement maintenance.


Despite misleading marketing messages by packing manufacturers traditional boxes should not be run "dry" or "dripless" but they can be "drips-less" than older plant based packings.. They, all PSS type or traditional glands, need to pass some water (traditional) or vent air (PSS type), or they can overheat. Trapped air or not passing of water can also lead to stagnation and corrosion of the shafting up inside the log.

This is what stagnant water on a traditional box set to not drip can do:


Some boats are more prone to trapped air in the log hence PYI's move to all vented/plumbed seals even on slow moving craft. "Burping" on some boats was more than just at launch time so vents make a lot of sense on all sailboats.

Newer packings can be pretty darn drips-less but should not be 100% dripless. it can be so minimal that engine warmth evaporates any drips before it accumulates.

Unfortunately I can't count the number of times an owner or yard mechanic has said to me "Yeah when I adjusted the PSS." and I ask "Did you replace the set screws?" and am treated with a blank stare? Scary stuff!

If a failure were to occur with a slipping rotor, in this scenario, it is installer error not the fault of PYI or the PSS seal.

I also very often see the vent holes plugged with brass or ss plugs. The vents should always be plumbed (power) or vented/used on sailboats. Metallic plugs should never, ever be used in the carbon rotor. There is a reason PYI uses a nylon hose barb and that is because the carbon is the most noble element in the galvanic scale and the differing expansion contraction characteristics between brass or SS and the carbon...

PYI says this in the instructions but many people choose not to read or heed them:

"Do not tighten or replace the installed nylon hose barb fitting with a metallic fitting (bronze or stainless steel). Metal hose barbs will damage the carbon and destroy the PSS."

Again, this type of failure, overheating of the seal, dissimilar metals corrosion or a split carbon would clearly get blamed on the PSS seal. Sadly on the "net" PSS takes the hit not the dolt who caused the failure by not following the installation instructions. These are examples of installer error not a failure on the part of the seal. I see the metallic plugs and set screw errors frequently.
Main Sail,
I think your post offers some good insight of what is wrong with PSS. It is just to sensative. We are sailors, not astronauts that are highly educated and trained to go on Apllo missions to the moon.

I want equipment on my boat that can be abused, not installed perfectly, can be overused beyond is "designed" capability, can be beat on and ask for more.

I worked on subs and what impressed me is how basic and strong these things are made. They are made for an 18 year old out of high school with a little training to be able to make work.

PSS is just to sensative for the average sailor. And I want no little plastic fittings on my boat holding back the sea.

Last edited by casey1999; 09-05-2012 at 02:07 PM.
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  #36  
Old 09-04-2012
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Re: Dripless Shaft Seal versus Stuffing Box

Quote:
Originally Posted by casey1999 View Post
MainSail:
Why do you have those perforated hose clamps on the PSS bellows? My understanding is they are not recommended due to accelerated corrosion factors.
A good perf hose clamp will be all 316SS just like an AWAB. Sadly many are cheap automotive or hardware grade and it gives the rest of the good ones a bad name. Unfortunately the AWAB's were a little too wide for the older style PSS bellows so I had to stick with perf clamps.. The new style bellows is slightly wider allowing the use of AWAB's, which I prefer to perforated clamps.

The ones that really suffer from corrosion in bilges are the T-band clamps. They can fail at the spot welds due to corrosion so if using T-Bands always keep the "T" up and out of the water....
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  #37  
Old 12-15-2012
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Re: Dripless Shaft Seal versus Stuffing Box

I installed a "Lasdrop" dripless systel about two years ago and haven't had an issue yet....nor a drop od water!

The manufacturer reccomended installing a spare seal on the shaft in the event the operational seal fails. This would eliminate the need for a haul out and is a good safety measure for a failure while underway.
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  #38  
Old 12-15-2012
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Re: Dripless Shaft Seal versus Stuffing Box

my boat came with a stuffing box. a couple of years ago i pulled out the flax packing and put in the gore type packing . it runs cool, drips very little when running & not at all when the shaft is not turning. it is not supposed to wear the shaft either so i am well satisfied with it.
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I've installed several lasdrops and like them. They use heavy hose, exactly like a traditional stuffing box, and no set screws, they clamp like the collar in Maine sails photo instead. The carbon is not directly threaded, the housing for it is instead allowing metal fittings to be used.

However I think the replacement seal on the shaft is a bit funny. More useful in that you have the spare available, but considering how hard it is to swap the seal out while held vertically on a nicely lit dry work bench...
Not bloody likely especially on the first try. You'd need to have excellent bilge pumps, all the tools including a hacksaw and heavy duty cutters etc, and a lot of luck.




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Re: Dripless Shaft Seal versus Stuffing Box

When I launched my boat last spring, I noticed water coming in. Turns out it was coming in through a crack/rip in my 3 year old PSS. Luckily the boat was still in the slings so I had them pull it out and
put it back on stands.

When I removed the bellows there were two problems - the bellows were too big and there was a tear. I checked the invoice from the yard in Annapolis that did the work and it shows the correct size PSS. Maybe they put the right one on the invoice and installed a different one. I have another theory though. I had a problem with a fuel tank vent hose. When the boat was pulled and topped off the previous fall, some diesel leaked out and the bellows spent the entire winter mostly submerged in diesel fuel. Perhaps this caused swelling which made the bellows appear to be the wrong size.

The tear may have been caused by a grounding wire that was probably cut when the stuffing box was replaced by the PSS. The sharp edge was lying near the bellows and maybe cut it due to vibration.

I wound up replacing it with a new PSS for many of the reasons Maine Sail mentions. I believe the failure was caused by the diesel spill and the sharp cut ground wire.

It sure was a bitch of a job to do - especially removing the old flange.

-my36
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