32-3 “Dripless” PSS v traditional stuffing box. Opinions, please?

[windblown]

We’re in fresh water, and find many things last longer in the less corrosive environment, but it’s definitely time to replace the PSS. We dropped the rudder before storing this winter, planning to do some maintenance on the rudder bearings, so it makes sense to do this now, too. However, after reading Maine Sail‘s warnings about removing the shaft coupling and needing to replace the shaft and have it professionally fitted, I am wondering if I should consider installing a traditional stuffing box. It’s recommended that the bellows on the PSS be changed every six years or so, which means pulling the shaft every time. Re-packing a stuffing box can be done without uncoupling the shaft. So, Vikings, I’d like your input.

 

[Loren Beach]

We installed a new PSS system in '95. Recollection is that the bellows has been replaced a couple times. There were no cracks in the bellows surface but I was concerned that the internal spring tension might be diminishing. Most of the yard guys that I have met say, off the record, that those should last easily a dozen years. As with all other rubber parts around the engine, keep all solvents away from it.
We boat in fresh water also.
Note that the vendor has changed their servicing time interval recommendations downward over the years, and also dropped the version without the air vent. Long ago, a PYI rep. told me that their lawyers were concerned about potential liability and those concerns overrode the experience of their engineers. (very much off the record).

With modern packing materials the traditional stuffing box seems to satisfy a significant number of owners. I still have the OEM packing hose bronze fitting off of our boat, stored in my basement. At several swap meets, absolutely no one was interested in making an offer on it. I could imagine having more "traditional" feelings about it if we owned an older design with a deep keel cavity to house a steady drip of sea water. But we have a rather shallow bilge area in the Olson and I keep it dry. "Bone dry" works best.
As always YMMV.

Also... if you pull the shaft every XX number of years, that is also a chance to check it for scoring, change out the cutlass bearing, and be sure of the coupling. Last time around we replaced the old style coupling with a new split coupling.

 

[tenders]

I had a dripless shaft seal for many years and was never very comfortable with it. It wasn’t bone-dry, replacing the bellows requires separating the shaft from the coupling (a horrible job on my v-drive setup), and its design allows it to go from functioning to catastrophe in a matter of seconds. I had a gasoline leak while on the hard for the winter which dissolved the bottom of the rubber seal and that was it for me - I went back to the stuffing box and won’t be revisiting the shaft seal topic again.

 

[Prairie Schooner]

We’re in fresh water, and find many things last longer in the less corrosive environment, but it’s definitely time to replace the PSS. We dropped the rudder before storing this winter, planning to do some maintenance on the rudder bearings, so it makes sense to do this now, too. However, after reading Maine Sail‘s warnings about removing the shaft coupling and needing to replace the shaft and have it professionally fitted, I am wondering if I should consider installing a traditional stuffing box. It’s recommended that the bellows on the PSS be changed every six years or so, which means pulling the shaft every time. Re-packing a stuffing box can be done without uncoupling the shaft. So, Vikings, I’d like your input.

Hi Deborah,
When we rebedded the strut our first year of ownership we took the shaft and prop to a marine 'drivetrain' specialist for inspection. The shaft was straight and smooth enough, however the butt and key way from the coupler end was somewhat damaged. The shaft was long enough that they cut about an inch off, faced it, and lengthened and dressed the key way. The point being that your boat's shaft may well not need replacement. Maine Sail is fantastic and I rely on his information regularly, though he seems to drift toward worst case scenarios. This is understandable if you've spent your career fixing other folks' problems.
Our boat came with a PSS and we had a new one installed in that process. So far no problems. But tenders makes good points.
Cheers,
Jeff

 

[Christian Williams]

My bilge is bone dry, which I like. But it wouldn't be if it rained much, since water down the mast defeats dry. A wet bilge is always dirty by evaporation, mine is clean--with a little attention.

The arguments in favor of safety of the dripless design are that they are popular, and used on comercial vessels and the Navy. It is true that an ancient dripless can sink a boat by rupture of the rubber. My last change of the rubber was after 8 years or more, and it seemed faultless. I see the safety factor as about equal to any thruhull, requiring awareness.

If installing a dripless, be sure to make contact with PSS. They answer the phone and email. Do not rely on boatyard policy, get installation requirements from the manufacturer. There is no need for any air vent or water vent option for our sailboats, if the owner is willing to burp the dripless after every haul-out. PSS will confirm that.

 

[Kenneth K]

I had my PSS replaced in 2021 after a wire got wrapped around it and split it open. This became an insurance claim.

The yard that fixed it purchased a rebuild kit, even though I had asked for a new PSS. I think they were smart because they didn't want to install the thru-hull vent that a new PSS would have required.

If forced to buy a new PSS, I think I'd rather plug the vent hole than install a thru-hull and vent line.

 

[bgary]

If forced to buy a new PSS, I think I'd rather plug the vent hole than install a thru-hull and vent line.

Thru-hull?

My vent-line goes up to the underside of the cockpit floor.

 

[Kenneth K]

My vent-line goes up to the underside of the cockpit floor.

That sounds like a better idea. I was thinking of Christian's installation, where they installed a through hull and a ball valve.

 

[Christian Williams]

For a while, PSS and boatyards recommended a dedicated thruhull for the constant irrigation of the unit. (Mine failed, but that's another story).

That was a "guarantee" against issues with the vent hose, which when installed to reach high above the waterline, could become detached and fall below the waterline. Which sinks the boat. That apparently happened enough such that product liability required the dedicated thruhull installation, which was "fail safe." (And yeah, many owners have no idea what that piece of rubber tubing under the cockpit does, probably secured only by 40-year-old cable ties, and would not appreciate the danger if it merely happened to fall into the bilge.)

Actually, slow speed boats like ours don't require either, if the owner just burps the thing when launching after haul-out. Which of course requires an attentive owner.

PSS will support any install in our boats with the simple "need to burp" solution. But some boatyards--mine--get very sensitive about it and may need encouragement from the customer not to automatically install vent or irrigation.

 

[Nick J]

The important thing to note on Main Sail's article is that all the problems he fixed along the way were already there. they weren't caused by replacing the cutlass bearing, it was just the project that brought it all to light. replacing your shaft seal won't cause misalignment, shaft ware, corroded coupling, broken shaft key, or a broken strut, but it will make all those problems more obvious.

as far as the shaft seal is concerned, there's valid arguments for both a PSS style and a stuffing box....there's also a lot of anecdotal evidence. The personal experience shouldn't be ruled out entirely, but it also shouldn't be taken as the only source of evidence. For me, I chose based on their standard use case. A stuffing box lets water in by design and relies on other systems to remove the water. A dripless shaft seal keeps water out and knowing where water is coming from is important to me. I live in the PNW, so I have a wet bilge, but I know it's rain water now. when it's dry, I have a dry bilge. I now know much sooner when problems arise and I think that's worth the risk of a potential failure of a PSS.

 

[windblown]

The important thing to note on Main Sail's article is that all the probl he fixed along the way were already there. they weren't caused by replacing the cutlass bearing, it was just the project that brought it all to light. replacing your shaft seal won't cause misalignment, shaft ware, corroded coupling, broken shaft key, or a broken strut, but it will make all those problems more obvious.

as far as the shaft seal is concerned, there's valid arguments for both a PSS style and a stuffing box....there's also a lot of anecdotal evidence. The personal experience shouldn't be ruled out entirely, but it also shouldn't be taken as the only source of evidence. For me, I chose based on their standard use case. A stuffing box lets water in by design and relies on other systems to remove the water. A dripless shaft seal keeps water out and knowing where water is coming from is important to me. I live in the PNW, so I have a wet bilge, but I know it's rain water now. when it's dry, I have a dry bilge. I now know much sooner when problems arise and I think that's worth the risk of a potential failure of a PSS.

Thanks for the perspective, Nick, and thanks everyone else, too!
This input is just what I needed.
I’ve decided to go with a new PSS, and I know the threads here are very good on that. I’m not sure where I’ll have to go to find a marine “drivetrain” specialist, but sounds like it’s the right strategy. I’ll replace the coupler with the split option, and the cutlass bearing while I’m at it. My current PSS has the vent to the underside of the cockpit floor, so I’ll do that again.
Now I’ll order the parts and wait for a winter thaw to get started.
I never regret making prophylactic repairs in the longrun,it’s just when the bills come due.

 

[Prairie Schooner]

@windblown
Merely as a reference point, this is where we took ours, in New Bedford, MA. The did the shaft work, checked the prop for condition and balance, and sold us a drive saver coupler.

Scandia Propeller - Fairhaven, MA|Propeller and Hydraulic Reapairs for the Boating and FIshing Community

scandiapropeller.com

A quick web search turned up some propeller shops in Rochester. It looks like they mostly specialize in outboards and I/O drives, but there must be old boats up there with shaft drives. If they can't do shaft work, they should know of a place. A good machine shop can check the shaft for true and do any work needed. They just wouldn't know the specifics of what was needed. Perhaps a member here from your region can recommend a shop.

 

[nukey99]

We have a PYY shaft seal on our new to us 35-3. We also had two of them on our Tiara 4000 express cruiser connecting two 450 hp diesels to the props. We had one our Catalina 320 in SF bay years ago. We never had a problem with one of them, and really appreciate the reduced water in the bilge, and the frustration of adjusting a nut or repacking a shaft seal in a tough to reach spot.

 

[windblown]

@windblown
Merely as a reference point, this is where we took ours, in New Bedford, MA. The did the shaft work, checked the prop for condition and balance, and sold us a drive saver coupler.

Scandia Propeller - Fairhaven, MA|Propeller and Hydraulic Reapairs for the Boating and FIshing Community

scandiapropeller.com

A quick web search turned up some propeller shops in Rochester. It looks like they mostly specialize in outboards and I/O drives, but there must be old boats up there with shaft drives. If they can't do shaft work, they should know of a place. A good machine shop can check the shaft for true and do any work needed. They just wouldn't know the specifics of what was needed. Perhaps a member here from your region can recommend a shop.

This is great. Thank you!