Packless Shaft Seal (PSS)

bkdehuff · #1 (**permalink**) 04-02-2004

There was a thread a while back concerning "cavitation" and vibration noise problems. A survey was done in this forum, and the responses were sent to Catalina Yachts for evaluation in relation to the C350, which has a dripless type shaft seal ("Packless Shaft Seal" aka "PSS"). Catalina has advised that improper maintenance of this type of shaft seal can result in vibration problems. Specifically, the PSS bellows MUST be bled of all air (i.e."burped") after launching the boat. Otherwise, the PSS will be deprived of cooling water. The importance of this cannot be overstated, since a PSS deprived of water will run hot and can cause damage. Even without damage, air in the shaft seal can cause vibration. A water injection unit to the PSS can eliminate potential problems by tapping into the raw water supply to the engine and routing a constant flow of water to the PSS.

Bermuda · #2 (**permalink**) 04-02-2004

"tapping into the raw water supply to the engine and routing a constant flow of water to the PSS."

IMHO, Just what we need, another system that can fail and bring the sea inside the boat.

Good old shaft log and stuffing box still remains a good functioning system to this sailor.

Capt Bruce

bkdehuff · #3 (**permalink**) 04-03-2004

There is nothing on a boat that is maintenance free. You have to keep a watchful eye on all your thru-hulls don''t you? And, what about that "good old shaft log and stuffing box." There is still plenty that can go wrong there too.

mdougan · #4 (**permalink**) 04-19-2004

There was a thread on the Crusing World BB a while back about this, and the consensus was that stuffing-less seals failed a lot, with pretty dire consequences. A few people recommended a type of flax made from gortex which is advertised as a dripless flax. One or more posters said they''d used it for some time with great results. I''ve repacked my stuffing box with it this year and we''ll see how it goes!

DelmarRey · #5 (**permalink**) 04-20-2004

I have rebuilt my fare share of industral water pumps that uses the same type of seal as the PSS They have been using them for as far back as I started rebuilding pumps (1969) and probably longer. The thing about them that I don''t like is when they fail, they fail right now with no warning. And then the shaft has to be pulled to install a new one. The same on a boat. At least with a stuffing box (packing gland on pumps) one can put some more packing material in and tighten it down some more, then do a good repair or replacement when you get back to port.
I vote for the good ole stuffing box. Carbon seals are for high speed, like power boats. And they recommend water injection anyway. As for sailboats, if you have one a little bleeder valve would work to get the air out, or just pull the boot back just enough to burp it then release.
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