Who has PSS shaft seal installed?

orientalnc2010 · #1 (**permalink**) 04-22-2010

I just got off the phone with an engineer from PYI about the PSS shaft seal.
Displacement vessels that power under 12 knots and have a cutlass bearing in the shaft log must bring raw water to the seal to ensure that it always has water. Has anyone plumbed their seal to a raw water source, if so where did you pick it up.
Who has a PSS shaft seal in service, with a cutlass in the shaft log, that just has a vented loop? Do you have any problems keeping water in the seal esp under full power? I was told that if you go hard astern water can actually be driven up the vent hose and spill out over whatever happen to be near or under the hose.
Thanks for any feedback.

erps · #2 (**permalink**) 04-22-2010

I have a PSS seal with a cutlass bearing in the shaft log but there are also a couple little water breather holes forward of the cutlass bearing. No issues for 13 years.

Propeller shaft and cutlass bearing picture by sv_nikko - Photobucket

erps · #3 (**permalink**) 04-22-2010

hmm, don't know why the picture is a thumbnail now. It used to paste big pictures in the threads.

lsbrodsky · #4 (**permalink**) 04-23-2010

I had a PSS shaft seal installed in my 31 in year 2 of ownership and it ran flawlessly the entire time I owned the boat. There was no vent hose but you had to remember to burp the seal after the boat had been hauled to be sure the seal was reflooded. When doing so, it was obvious that there is enough leakage through the cutless to lubricate/cool the seal bearing surfaces. My experience with this same design on large naval vessels was that forced injection cooling was required because of the large bearing size, higher loads, and higher rpm. This is a proven design with decades of operation. When I asked the factory, back in 1993, why the PSS was not standard their reply was that parts might be hard to find in remote regions of the world where a standard seal could be packed with almost anything and still function.
Larry

T37Chef · #5 (**permalink**) 04-23-2010

I will be installing one this weekend. The vent hose is to prevent/reduce crevice corrosion I believe. I have been advised that the hose only needs to be vented, not plumbed into a source, just well above the waterline.

lsbrodsky · #6 (**permalink**) 04-23-2010

No, the vent hose is to assure that no air gets trapped in the seal; it is always vented precluding the need to ever burp the seal or worry about air. Mine was not vented and I never had an air problem except when I hauled the boat. You had to remember to burp the seal when it was splashed. Maybe the vent requirement is to avoid operator error. I suppose with the right configuration cavitation might result in drawing air into the seal but I don't know how that would happen on a PSC.
Larry

orientalnc2010 · #7 (**permalink**) 04-25-2010

Thanks to all for the response. Thanks Larry for the first hand info that I was hoping to receive, based on your success I will not plumb water to the seal. All PSS shaft seal now come with the nylon barbed fitting already installed in the carbon so I will be adding a vent hose. I agree with your assumption that PSS did this to eliminate user error when it comes to manually burbing the seal. In my previous boat, a sabre 34, I did install a PSS seal and I had to remember to burb it each time we launched the boat, not a big deal.