Dripless Shaft Seal & Water Pickup Hose?

[Mark Sutherland]

I have a dripless shaft seal (aka PSS?) on my '86.  I've never had an issue with it, and hence never spent much time down there looking at it.  There is a hose coming off of the unit.  Looking at photos online, I've seen this hose referred to as a "Water Pickup Hose", which, in the photos online, disappears out of the photo, seemingly to some water source.  In my case, BEFORE my last bottom paint job, my PSS had a hose on it that was about 4 or 5"(?) long and sealed with a plug in the end of it, pointing straight up. My bilge has always stayed dry when it's not raining out, so my PSS was apparently not leaking. After my last haulout, my invoice stated, "Replaced the vent line hose with new longer hose".  Seems they removed the existing 4-5" sealed-end hose and replaced it with a hose lead all the way to the space under my head sink.  Their new hose had a brass plug at the end, said plug having a small hole drilled in it to allow water to bleed out of it.  They mounted it high on the wall directly above my main power switch (under the sink), which really ticked me off because it bled water down on the main switch when I ran the engine.  My questions: 1)Was my original short, sealed hose an incorrect installation because it was below the water line or was it ok?  2)Is it proper/necessary for this new hose to bleed water out of it when I'm running the motor?  3)When I reroute this new, longer hose away from my main switch, can/should I install an anti-syphon fitting on it so I can run this water-bleeding line back down to the hull level so it's not spitting water indiscriminately?  Thanks much for any advice you can share.

[patrice]

Hi,

Not an expert on this type of equipment, but I can assume there has been lot of improvement and different model.

The company still being in business, You should ask them and get proper installation tip.

[Roc]

What they did is correct (seems like your original hose was too short).  The hose should run above the water line.  It's there to make sure there is no air pocket trapped in the bellows.  Otherwise, the seal will not be lubricated (via the water).  If you don't like where they put the hose, move it to another location, just make sure it's above the waterline, and doesn't fall below the waterline when heeling.

[Ken Krawford]

When Catalina first began installing PSS dripless seals, they were set up like yours.  It turns out there is a problem with air getting into the bellows when the boat is hauled and the tube is used to "burp" air from the bellows.  This is a typical setup for vessels that run less thank 12 kts.  Later they T'd this tube into the raw water intake thereby eliminating the need for burping the bellows after haul out.
PSS recommends changing the bellows every 6 years.   At least once a year you should also check the compression on the bellows and make sure it hasn't slipped.  There are 2 pair of  double stacked set screws in the stainless rotor that hold the bellows in compression.  PSS has a chart that details the amount of bellows compression (in inches) needed to achieve a good seal and is based on the shaft diameter.  Make sure yours is within specs.

[Mark Sutherland]

Clarification: I don't know the age or exact brand of my shaft seal.  I used "PSS" to mean "Packless Shaft Seal", but don't know whether my unit is the PYI Inc. brand of PSS. 

Followup question: I read hear that people love their Dripless Shaft Seal because it keeps their bilge dry.  Why is mine spitting water out of the subject hose?  It's a small amount of water but it's certainly not going to keep my bilge dry.  Thanks.

[Roc]

Maybe you can show a picture of your set up.  My hose, which is far above the water line, does not have any water coming out of it.  PYI used to have a "slow" speed seal, basically one without a hose attached as an automatic way of "burping" trapped air, because they felt a vessel moving slowly (i.e. a sailboat vs. powerboat) does not have the water sucked out of the bellows cavity, eliminating the water lubrication of the seal.  I think they figured out, that's not the case, and they specified the system of Tee-ing the hose out of the exhaust, to keep water in the bellows, not only for powerboats, but including sailboats.  Then they changed it to specify a hose, leading to nowhere, but placed well above the water line.

[Ralph Masters]

Mark, et all,
When you back down the prop pushes water back toward the shaft and into the stuffing box, thus every time you reverse you have the potential to have a bit of water spit out of the vent hose on your PSS.

Ralph

[sailr4]

Yes, it happens in reverse. run the hose into a small bottle (gatorade works well) to catch the drips.

[Mark Sutherland]

Thanks for the helpful responses.  I have a follow up question.  I'm hearing loud and clear to keep the end of this "burping" hose above the water line, however, I'd like to mitigate the random spitting of water into the compartment under my sink.  So, I want to extend and run this burp hose back down towards the hull and into the bilge.  I'm thinking I should install an anti-siphon device in the middle of the hose run, mounted to a bulkhead, above the water line, then run the remaining half of the hose back down to the hull/bildge.  Am I on the right track with the anti-siphon device or is it unnecessary?  Thanks for your input.

[DaveBMusik]

My surveyor just went over this with me. He said there is no need for a hose but you need to pull the bellows back to burp the air when you launch in the spring. He also recommended placing a hose clamp on the shaft in case the set screw gave way.