Brand NEW Dripless (PSS) - leaking with small movement - is this normal?!

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sailorknots77@reddit

No one ever really mentions this for sailboats. The props just don’t spin fast enough for PSS seals to work correctly. Go get a tides or other lip seal type.

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> The hose keeps compression between the black seal and the stainless rotor. That's not true, on a sail boat of this size the hose is an air release/equalisation device. It's run up above the water line and isn't capped. > No one ever really mentions this for sailboats. The props just don’t spin fast enough for PSS seals to work correctly. Go get a tides or other lip seal type. How does the prop spinning cause the PSS shaft to work? Relevant: I've got a PSS shaft seal that has worked flawlessly when the prop spins and when it doesn't.

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H0LD_FAST@reddit

Ya I don’t know what that other poster is talking about. The hose allows water into the seal to cool it. The bellows keep the tension between the collar and seal surface. Bumping it (probably with enough force like op put on the hose) is enough to make mine burp as well. It really doesent take much. Mine started leaking at the end of the winter this year and I don’t want to deal with the catastrophic possibility so I’ll be going back to a traditional stuffing box.

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tx_trawler_trash@reddit (OP)

It seems like that little bit of pressure on the hose causing that much water can’t be normal, you’re saying it is? While underway can I expect this much water?! Just thinking even normal vibrations could cause an influx of water if that’s the case?

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jonnohb@reddit

I have no idea what that guy is talking about, I have had my boat for 3 years and never seen so much as a drop come in through the PSS

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wlll@reddit

Exactly the same experience here.

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tx_trawler_trash@reddit (OP)

Out of my element here - always had a stuffing box, but yeah that little movement seems like a major design flaw if that's expected, but again, I know nothing of these things - it doesn't drip normally, but pushing that hose like in the video causing quite a bit of spray

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jonnohb@reddit

You are going to have to inspect it closer and see what's going on. I believe there should be enough pressure in the bellows to keep everything tight enough that you shouldn't be able to move things that allow water in. Adjust the bellows and see if the collar is loose or damaged, probably loose set screws.

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tx_trawler_trash@reddit (OP)

When it was installed one side didn’t even have set screws in it so this could very well be it..

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sailorknots77@reddit

From what I can see, it’s perfectly normal. You’re breaking the seal between those two faces. The accordion hose is compressed a bit which keeps pressure between those two faces. Underway, it shouldn’t leak at all.

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tx_trawler_trash@reddit (OP)

Thanks again for the info - I need to just put some miles on it close to port and see what happens I suppose

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tx_trawler_trash@reddit (OP)

I didn’t know that so that’s good info (not that I was asked in the first place by the shop lol)

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sailorknots77@reddit

They aren’t bad, just that there are better options for slower spinning shafts. For a high speed shaft, it’s a great option.

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whyrumalwaysgone@reddit

No this isn't normal! 2 possibilities 1) the stainless collar needs to be moved aft. I don't think it's this, but it's pretty common 2) the hose barb that your cooling tube goes to is cracked

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tx_trawler_trash@reddit (OP)

Thanks! I’m going to have the guys that did the work take a look tomorrow (though my confidence in them is shaken)

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whyrumalwaysgone@reddit

For what it's worth, unless you are a very fast sailboat you don't need that hose to the drip less, it can be replaced with a plug. Less plumbing, less holes in the boat. I think the cutoff is 12.5kts but check the manual

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wlll@reddit

Are you sure? My reading (section 15) of the fitting instructions is that for boats under 12 knots and without a bearing in the shaft log you can either water cool using the hose, or use it as an air release, but there's no mention of picking neither option.

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whyrumalwaysgone@reddit

The manual doesn't mention it, this is from calling and speaking to the PSS techs directly. You can cap the hole and have no hose, only caveat is you have to "burp" it manually when boat goes in the water after a haulout. I used to install these at a yard for a living and that's what PSS recommended at the time. My preference for my own boat was to skip the hose as another point of failure, it's basically an open thruhull with no valve.

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wlll@reddit

Well that's interesting, how did you cap it?

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whyrumalwaysgone@reddit

Just a pipe plug and ptfe, you unthread the hose barb and put in a plug, it's a standard thread. All the barb/hose assembly does in a standard (<12kt) install is burp the air for you automatically, and thats only an issue on launch day. It works fine, but it's a decision that should be made by the boat owner not a shop (we always asked first) but most cruisers preferred it plugged.

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wlll@reddit

Good to know, thanks, PSS confirmed. Wish I'd known that a week ago before the boat got half-splashed and had to be re-hauled :)

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tx_trawler_trash@reddit (OP)

Interesting…my boat is definitely not capable of 12.5 kts I’ll look into that!

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beamin1@reddit

I see the steel clamp and can't even read the post, don't put steel on boats people, use hq stainless steel ffs.

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vanalden@reddit

This is normal and has a purpose. Have you downloaded the instructions for the PYI PSS? It's a good product, but does need some understanding. How it works - The compression of the rubber bellows pushes the carbon infused stator against the stainless steel rotor, which is mounted on the shaft. After an hour or so of running, the stator and rotor bed and polish to each other, which should reduce any spray of seawater while running to minimal. It is possible to reduce this further, to virtually nil, by increasing the tension of the bellows. Loosen the rotor's locking screws and move it closer to the stator, in 1/4" adjustments. It's a hard push, so be ready for that. If the shaft log has been drained from the boat being lifted, upon relaunch let trapped air out of the bellows by nudging the stator away from the rotor. You did this by bumping the hose that has been attached to the air bleed spigot on the stator. This hose is optional and provides a permanent route for 'trapped' air to escape. And a 'sight-glass', if the hose is transparent. 'Yep, there's water in the seal. Good.' However, if the hose breaks just above its attachment point to the stator (and below the waterline) the boat might sink. My builder omitted the hose, as a safety measure, though this increases the chance of inadvertently burning the seal from running it when dry. Take your pick as to which risk you prefer. Your installer assessed you as being competent. Another purpose of being able to bleed the seal is to flush out any detritus (seaweed, fish scales, drug baggies, etc) which might find their way (I don't know how that got there officer!) between the stator and rotor, to disrupt the seal and cause leaking. Enjoy your PYI PSS. A few friend boats have gone through NWP with these. Lots of motoring, no problems.

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tx_trawler_trash@reddit (OP)

Thank-You for a detailed explanation - I do admit my lack of education on the subject, any amount of water coming in there at that rate terrifies me, so I’m grateful for info as to why this might be the case - I will likely try to increase the pressure on the bellows and go from there.

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vanalden@reddit

In your video I saw that water would gush in only if you pulled on the hose. Doing this pulls the stator and rotor apart, letting the water in. No water should come in if the stator and rotor are pressing against each other, undisturbed. So this means it's important to avoid something falling against the hose, such as an oil drum or similar. That could sink the boat while you're at the knocking shop.

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tx_trawler_trash@reddit (OP)

Yes that is exactly my worry!

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vanalden@reddit

A solution to contemplate is to insert a blanking screw into the threaded hole in the stator, which currently has the spigot in it. All concerns about the hose and the hole would be eliminated. However, you would need to give the seal a little burp before each break in use and certainly after any lift-out or drying-out. This means a small amount of water in the bilge under the engine each time, which might not be a concern, but for some owners is. There should have been a blanking screw included with the PYI PSS kit, but if not, a dealer or PYI will have one for not much. They're pretty good at customer support. If you're clever and quick, you can do the swap while in the water. Eek! But also give some thought to leaving things set up as they are, with the advantages and disadvantages understood. And the required precautions in place. You might be able to zip-tie the hose against a frame so it doesn't get bumped and cause leaking.

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tx_trawler_trash@reddit (OP)

Thanks! Yeah I’m going to talk to the shop that did the work / install today about it and see what they say, that’s a good suggestion so I’ll mention it but yeah I’m not well versed in all the trade offs so need to digest those for sure

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wlll@reddit

Agree it's a good product, mine has served me well. > Loosen the rotor's locking screws and move it closer to the stator The fitting instructions gives the exact amount the bellows should be compressed, there's no need to get there by trial and error. Plus, the grub/set screws aren't re-usable, once you've tightened them onto the shaft you're meant to replace them if you take them off. > upon relaunch let trapped air out of the bellows by nudging the stator away from the rotor. This shouldn't be necessary, the hose that comes out of the top of the stator is a vent, it's run up above the water line (details in the instructions, https://www.pyiinc.com/downloads/pss-shaft-seal/pss-type-a-pro-seal-instructions.pdf). > This hose is optional That's not mentioned in the fitting instructions.

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KCJwnz@reddit

Dripless shaft seals are pretty proven. That being said it looks like your particular set up may be a bit sensitive to that burb hose. Imo pss is better than a stuffing box but I'd either get rid of the burp hose or secure it. Looks like the burp hose is acting as a lever on the shaft seal when pressure is applied. Not a huge deal at the dock but could be an issue in action. Don't get too mad at the yard but definitely talk with them about it

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tx_trawler_trash@reddit (OP)

Yeah I definitely will talk to them but not going to be a dick about it - thanks!

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Same_Detective_7433@reddit

I was checking the gearbox on a boat recently, and came into contact with one of these, it did exactly that, scared me a bit, but did not leak unless I touched it. I left it alone, it was fine for two week of motoring into the wind. No idea beyond that, but it did exactly what your video shows.

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tx_trawler_trash@reddit (OP)

Thank you! That’s reassuring but still blows my mind thats the case - about to do a longer windward trip so it scared the hell outta me

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wlll@reddit

As /u/whyrumalwaysgone says the stainless steel collar needs to move aft, it effectively compresses the bellows part, how much you need to slide the collar depends on the PSS seal type\*, the details are in the technical data sheet. It's different for different shaft diameters and bellows type. I've just done mine and though I've not got it back in the water yet so can't test, it /looks/ like you might not have enough compression. If you do loosen the set/grub screws you need to note a few things: - There should be 2 stacked grub screws in each hole, if there aren't it's not been installed properly. - You aren't supposed to re-use the grub screws that were against the shaft. You can swap the order of grub screws in each hole as long as the top grub screw hasn't been flattened (you should be able to see the difference). If yo \* PRO: Silicone bellows, Non-PRO: Some other rubber bellows.

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Pale-Egg-251@reddit

Read the manual. It’s not that long. You may need to adjust the face seal a tiny bit to compress the bellows a bit more after a brief break in period. Sometimes you need to move the bellow back to “burp” the air out of the seal as well.

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nomadknight@reddit

Your video would be better if you had the dripless shaft seal in the centre so that it is more visible. Instead it's barely at the bottom of the video (exhaust elbow front and centre instead!). Anyway, after watching it a few times I can say that this is not normal behaviour. I have a PYI PSS on my monohull and moving the vent hose doesn't do anything. However if I move the carbon flange aft with a bit of pressure, then yes some water will come out (this is called burping the seal). Good thing you're catching this now and not when you're far off shore!!

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tx_trawler_trash@reddit (OP)

Yeah it’s a bit tight in there so even taking this video was a struggle… I was planning a 6 day passage leaving this weekend so yeah I guess it’s good I accidentally wiggled that and saw the water coming out in my slip versus something happening offshore…

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