Dripless shaft seals [Master Thread]

[Kenneth K]

PYI, when I spoke with them last summer, recommend putting a locking retention-collar on the shaft in front of the disc to ensure it did not move forward.

Bruce, when you spoke with PYI, did the subject come up about the vent tube. The older models, like mine, didn't have a vent for the 1" shafts. Apparently all of the newer models now use the vent tube.

Did you originally have the vent tube? Did you upgrade to one? Or is it not worth worrying about?

(Other than making it "burpless", it seems I read somewhere that it lets oxygen in to prevent corrosion of the SS shaft.)

 

[bgary]

Did you originally have the vent tube?

I do not have the vent tube. Christian showed me how to "burp" the bellows after the boat was hauled for the survey, I did it when the boat first went into the water up here, and again when she splashed after the bottom job. The hardest part is remembering to do it before motoring away. I write myself big notes and tape them in places where I can't miss them...

I'm planning to have Everett Yacht Service (an installer PYI recommends) replace the whole thing next time I have boat out for bottom paint - either this fall or next spring, haven't decided yet - so I'll have the vented version next. The one I have now beginning its 7th year, I think, they recommend replacing the bellows at 6 years so I'm actually past due for replacement.

The replacement itself should be easy. I'm concerned about how much work it might be to get the coupling off the forward end of the shaft, but... that has to be done, whether I'm replacing the whole unit or just the bellows, so hopefully that skillset is part of what EYS is going to bring to the table.

Bruce

 

[Geoff W.]

I'm planning to have Everett Yacht Service (an installer PYI recommends) replace the whole thing next time I have boat out for bottom paint

I had them replace my drip-shaft with the PYI dripless when I was up there in November. Has been great so far.

 

[Christian Williams]

My dripless is probably 10 years old. Iʻll replace the whole thing next haul-out. Not gonna try to do it myself.

Surveyors are usually not fanatical about the 6-year replacement schedule. Eyeballing the thing gives an idea of the state of the rubber and the compression and the spinning flanges.

 

[Kenneth K]

Want to have the prop shaft shortened too if I remove the shaft coupling to replace the PSS. That means an opportune time for a new cutlass bearing as well.

I suppose shaft removal means dropping the rudder on the 32-3?

 

[Christian Williams]

Consolidated from another thread:

We have a PSS on the boat. I've loosened the set screws tho haven't been able to move it yet. That might be a task for today. More boat yoga.
You're very right. This is a major reveal of a system and it would be foolish to waste the opportunity to maximize things. Seems to be a recurring theme, "Well, as long as we've got it open . . ."

You said you had trouble moving the PSS. Remember that there are usually 2 set screws under the initial two that you can see, for a total of four set screws to remove, before the PSS can be moved.
Frank

Frank Langer said:
for a total of four set screws to remove, before the PSS can be moved.

Also those set screws are NOT reusable. So before you put it back together you'll need to order replacements. Not sure how old your PSS is but if it's 6+ yo or more it may be time for that project too(while your in there). They sell rebuild kits with new bellows, clamps, o-rings, and set screws of course. I think I paid about $90-100 for the kit but that was a while ago...

Serendipity
84 E30+ Hull #632
Universal 5416
Lake Michigan

There are previous threads/posts about timing of replacement/longevity of PSS. The manufacturer in Seattle used to recommend replacing or rebuilding every 15 years, then shortened it to 11 years, now at about 6 years. A sailor at our marina showed me the one he removed at 15 years, and it looked like new--thick, flexible rubber! As mine was about 18 years old, and still looked perfect, I phoned the PSS tech to discuss. He said that they last a long time--he has seen good ones at 25 years, as long as they have not been immersed in oil, tranny fluid, etc. He said their lawyer had recommended a more cautious timeline recommendation. As we were planning a trip to more remote areas, where service is not available, I decided to replace ours at that time. Upon removal, the old PSS rubber and other parts were fine, and I've kept them as a spare in case I ever need a similar rubber hose (eg. temporary exhaust hose repair?). I don't regret replacing mine, even just for peace of mind, but for sure I'm not going to replace it every 6 years unless I spill lots of oil on it. However, I do recommend checking it regularly for any cracks or chafing in the rubber bellows, ensure the double hose clamps are positioned correctly and tight but not overtight (don't cut the rubber) and the set screws are tight. The old PSS needs to be "burped" of air after haul-out to avoid it overheating.

Having said all this, I'm no expert in this area, am not second guessing PSS lawyers, don't want to get any tech staff in trouble (they were very pleasant and helpful), and am only sharing my experience for your consideration.
Frank

 

[Christian Williams]

I had my 10-year-old Dripless replaced this season. It was installed in 2012 by the P0, and showed zero sign of deterioration or issues.

Info re alternate DSS lubrication plans:

E381 - Haul Out for Paint, Prop Shaft, Dripless Shaft Seal 2021

... Here in Southern California, hauling a boat out is easy to put off. It had been nearly four years for Thelonious II, and the hull was showing gray barrier coat underneath its hard black bottom paint. A dive service cleans the hull monthly...

ericsonyachts.org

 

[paul culver]

I'm a happy PSS user. Just wanted to add a caution I read somewhere along the way against use of ozone generating air cleaners in the vicinity.

 

[Martyn]

Since buying my boat a year ago the PSS has started to drip ever so slightly. The rag in the bilge used to be boned dry, now damp. Upon inspection I noticed about 1/8th + inch play in the PSS. Movement that when jiggled by hand allows a bit of water to enter. Also, the vent on the PSS doesn't vent, its just got a nut in it.

Is this play normal and the small amount of water equally nothing to be concerned about, or is there an adjustment to the compression that I should do to increase the pressure?

Could it be that the engine is out of alignment from the shaft ever so slightly and this could be causing the play and the water to be present?

 

[Christian Williams]

You should be able to press the bellows apart with fingers so the plates separate and water comes in, that would be normal. Called "burping the PSS".

Sometimes debris gets caught between the plates, and a press apart and quick wipe should clear that.

Such a debris leak usually results in a fine spray pattern evident on both sides and across the bilge.

The bellows can be moved to a new compression degree, if necessary. They're supposed to be rebuilt or replaced on a schedule--maybe 6 years, although many go longer. Good idea to be satisfied that the bellows is strong, the contact is firm, and the leak is stopped by cleaning.

 

[bigd14]

Please look VERY closely at the shaft seal bellows with a bright light and phone or mirror before deciding to tighten it. Damage can be hard to see, especially if access to the area is limited. I'm still amazed my old PSS didn't spring a leak and sink the boat before I bought it and hauled it out to fix that and other issues.

e30+ Shaft Seal

Once I removed the quarterberth bulkhead I was able to get to the old nasty shaft seal. Pictures are worth a thousand words... But to add a few more, the crack in the second photo was so fragile, I could poke my finger right through it. This boat was very close to sinking. What are other...

ericsonyachts.org

 

[Dave G.]

Martyn,
If you do not know the age of your shaft seal a wise step is to buy a rebuild kit for it. They cost about $100-125 depending on the model. You get a new bellows, O-rings, set screws, & clamps. Unfortunately you will have to pull it out of the water to do the upgrade. I recommend you also buy their stainless steel locking collar for "extra" holding power. When I did mine the bellows was pretty much worn out with hardly any spring left in the material. I was surprised how difficult it was to compress the new one by comparison. Of course the old boat rule applies when you start pulling shafts out of couplers that haven't been touched in years........etc, etc..

 

[Christian Williams]

Cross reference to: https://ericsonyachts.org/ie/threads/another-pss-cautionary-tale.20907/#post-167771

 

[Christian Williams]

I had a bilge flood as result of dripless system failure. Sea water rose to the floorboards, completing their ruin and requiring replacement .

It was not the dripless itself, but the optional irrigation system installed by the boatyard.

The full acsount is here. Be aware of the three options for sailboat dripless installs, which are: hand-burp, air vent, and seawater irrigation.

My boat might have sunk in the slip as a confluence of accident factors described in the video.

Dripless Shaft Seal and other Issues (20-minute video)

Choose "Watch on YouTube." Dripless troubleshooting, Ray wheel pilot fix, installation of galvanic isolator, sail cover revision. "Why plumb a sailboat's PSS to a thruhull and hose, when that is not necessary for vessels that don't go fast, like motorboats? Of the three options for PSS...

ericsonyachts.org

 

[frick]

I think that dripless shaft seals are bad idea. They can fail and sink your boat. The old Stuffing boxes might drip but they are not prone to a rapid failure

 

[peaman]

I think that dripless shaft seals are bad idea. They can fail and sink your boat. The old Stuffing boxes might drip but they are not prone to a rapid failure

I'm considering replacing my PSS with a stuffing box for this reason. The PSS is perhaps four years old (I've had it 3 years) and recommended major service is at six years. It looks like replacement with a stuffing box may be no more hassle than doing the recommended service.

 

[Pete the Cat]

I'm considering replacing my PSS with a stuffing box for this reason. The PSS is perhaps four years old (I've had it 3 years) and recommended major service is at six years. It looks like replacement with a stuffing box may be no more hassle than doing the recommended service.

The only potential problem is if the PSS installation scored the shaft. I would suggest Maine Sails (Compass Marine How To) site for basic stuffing box installation information. If the shaft is scored you might be able to avoid the scored part by shortening or lengthening the rubber tube you replace. As usual, I greatly respect his general descriptions of how to install and maintain the conventional stuffing box--he did use graphite in his own boat and I have always used it in mine with the green clay and made it dripless. I agree with the cautions about using clay (that it can clog the water needed to cool things in the box) but I have used this stuff and made it dripless for several thousand motoring hours with no problem--but installation and break in requires fussy attention for the first several hours. I do not recommend clay for someone who is not willing to be very careful with the installation. I had always intended to propose an addendum to Maine Sails instructions about how using clay could be made dripless--but he had a stroke before we could work it out and I lack his photographic and layout skills. I am willing to write something up about going dripless with a conventional box if there is a demand. Meanwhile, his instructions are very well done.

 

[Christian Williams]

Note that Cummings (Maine Sail) is an advocate of dripless shaft seals.

Dripless Shaft Seal versus Stuffing Box

www.sailnet.com

Despite my own experience (Post #54 ) I still like them and see no need to go back to a constant drip and repacking simply because a total failure of a dripless failure will sink you. So will a collision with a containership, and both can be avoided by paying attention.

I come to the following brilliant conclusion regarding the choice: if you have a conventional stuffing box, fix it up so it works right. If you currently have a dripless, fix it up so it works right.

Having solved this, I will move on to the Middle East, which also needs my help.

 

[Loren Beach]

Some forgettable trivia about the PSS seal...... per one of their employees I chatted with decades ago, they stopped selling two separate types (vented and non vented) due to liability concerns. i.e. their attorney was worried that one of the non vented versions might get resold to someone with a planing hull and the seal would run dry and ruin the seal disc.
The idea was for the planing hull power boats to introduce water into the seal area under way to make sure that the forward motion did not suck all the water out of the shaft ally.

I believe, and it's only an opinion, that they also decided that some sailors were not bright enough to burp the sometimes-trapped air out after a launch, and having the vent hose taken above the DWL would prevent this.
(FWIW, on our model the shaft alley angle is fairly "flat" and, as a caution, when I have burped the seal after launching it's always been full up with water already.)
A steeper angle down for the shaft could indeed trap some air, so this advice varies with boat model.

I do not have an original brochure from the 90's handy anymore, but recall that the specified replacement time for the bellows might have been 10 or 12 years. They shortened it based on input from customers, I recall. Gist of it is that their lawyers may have had more input into the instructions than their engineers.

As for the traditional stuffing box, note that the material used has changed and evolved over the decades. Quite a bit.
And... it's common to buy a used boat and find the the previous (multiple?) owner never really attempted to figure out to do it right. My takeaway is that ALL of these systems require some education and hands-on experience. Some of us are a lot better at this than others.....

I was baffled by the rock-hard remnants in the stuffing box on our fixer-upper boat in 1994, and changed to the PSS. Perhaps I should not have chickened out so easily. OTOH I have had no leaks from the PSS for over 25 years, replacing the bellows only twice.
Probably yet *another* boating question with several correct answers!