Tides v PSS

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Hippocampus

Guru
Joined
Jul 27, 2020
Messages
3,908
Location
Plymouth
Vessel Name
Hippocampus
Vessel Make
Nordic Tug 42
Always had PYI devices. Only trouble I ever had was need to add cooling water to the latest version. As part of routine maintenance noted evidence it was heating.
As part of the survey findings on our new to us boat it was mentioned there was a slight leak on the PSS. I like perfection on key systems so asked yard to deal with it as we’re in a different state than the boat at present. They said they couldn’t move it. Couldn’t slide it at all so after trying heat, solvents and brute force used a cutting wheel and cut it off.
They want to replace with it with the Tides device. Never had one in the past.

What’s the +/- of Tides v PSS? Lip seal (no moving parts) v aligned plates (moving parts and pressure in bellows).
 
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Have had both. Our AT-34 had the Tides seal. Current boat has PSS by PYI and it has worked well, was replaced a year before we bought the boat in 2018. It weeps/mists slightly so I placed a cut out partial clear water bottle to stop the misting from hitting the bottom of the generator drip pan. Both styles require replacement at recommended intervals. If you go with the PSS, make sure they install the second grub screws that locks the first one in from backing out. (I wonder if that is why they could not remove the old one, only removed the jam grub screw?) I see PSS has two styles seals now. Interestingly, our current boats rudder shaft seal is a Tides, which is another story…

PYI Inc. | PSS Shaft Seal
 
I've had both. Neither one on any boat I've had was 100% all the time never a drop. I think "mostly dripless" is a better description for them than dripless. PSS tends to mist when it has sat a bit between uses due to the salt. Otherwise I like them very much. Sure would be a shame if the yard didn't remove the 2d screw from each hole. If they missed that then the install might be out of their league and it isn't that hard.


If you go with the Tides then you need to add at least one or two of the spare seal carriers if you have room on the shaft. If the seal goes out and you don't have the spare seal carrier then off to the yard you go. And they sell the spares for a reason. The seals do go bad.


Both systems though are pretty good "mostly" dripless seals and I'd go with either one. Lots of owners install a spray shield of some kind like Kevin mentioned.


Don
 
I have also had both and switched back to Tides on my current boat. I didn't care for the PYI/PSS device. I found the bellows tensioning to be very finicky, especially as the bellows aged and lost it's spring. And we are not talking about age past it's service life. I'm talking about 3-4 years old. I also had rust and pitting on the rotor. There was always a spit ring around the seal where it was slinging some amount of water. I was not impressed.


With Tides there is no bellows, not adjusting, and no rotor to rust pit or get stuck to the shaft. The seal is a lip seal just like is used on millions and millions of engines and other machinery throughout the world. And you can pre-install one or more replacement seals on the shaft allowing for replacement while in the water, and without removing the shaft.


Both of them need proper cooling, and will fail without it. If you draw water of the engine cooling system, be sure to draw it off upstream of the engine and gear cooler zincs. Otherwise you can end up with deteriorating zinc fragments getting into the feed hose to the seal and blocking water flow.
 
I have had both. On my charter boat I always used the PYI with great success. The trawler came with the Tides on both the shaft and rudder. The shaft unit was leaking, so it was replaced with a PYI. The rudder would require serious modification to convert it to a PYI, so I replaced the seal and left it. Have replaced the rudder seal again, 2 years ago. This fall I will have 4,000+ hours on the engine, and will probably replace both again when I haulout. While I like the concept of the Tides seal, it just seems like it should be lubricated like an engine crankshaft seal.

Ted
 
Any thoughts about Lasdrop? Reluctant to go back to a traditional stuffing box even with the new style stuffing,
 
Hippocampus - can I ask why you're reluctant to use a traditional stuffing box? Even before GFO packing I was able to keep drip down to a very bare minimum - a small 2-cup tupperware catch basin easily handled it for at least a couple days.

Right now I have a brand new PYI dripless shaft seal for sale on the Classifieds of this site (1.5" shaft x 2.0" stern tube). I bought it and decided not to install simply because my shaft is extremely accessible thus easy to service and check. Years ago I replaced the original stuffing box with the large single annular nut with the dog-eared compression plate with a pair of 5/8" nut/bolts which is easier to adjust and requires no special tools.

For my thinking, unless the owner simply won't check/maintain their stuffing box, or the access to stuffing box is difficult, I strongly prefer traditional as I've seen them go well into 25-30 years of service or more.

Just curious about your thinking.....like I say, I was very close to pulling the trigger, then chickened out. BTW - anyone want a brand new PYI dripless shaft log????

Peter
 
I'm facing this same dilemma at my next haul out. I'm very disappointed with the PSS seals, they sling salt spray everywhere and at best mist up the engine room with salt. They seem to work well if there is zero vibration and you have things perfectly aligned, but then the bellows relax and you are back to the salt shower. In my case I have a PTO near the shaft seal so this mist just destroys any fittings nearby. In general I think these were partly or mostly responsible for the excessive corrosion in my engine room during prior ownership.

I had the Lasdrop seals on my last boat and switched to the GenII version which worked well once properly adjusted. I may switch out to those or go back to traditional packing box and Teflon packing, at least those don't spray.
 
Lived with traditional stuffing boxes for the first several decades. Admittedly before current packing material. Was another thing on the check list. I’m nervous Nelly. To replace the stuffing and make sure I got it all out wanted to be on the hard. Recent years only do short hauls for the bottom. Be another thing on the list. Still, you’re right it remains a very viable choice.
 
Boat before Weebles was a Willard 30. Stuffing box was pretty buried in a cabinet and difficult to service which means it needed service - it was both heating-up and dripping excessively. There was no Internet back so I had no idea what to expect if I did it in the water., but I was pretty broke and idea of hauling was out of my budget. I borrowed a spare pump, got all sorts of strips of t-shirt rags to stuff around if needed, etc.

Then I backed-off the nut. Not much came out. I was stunned - I was expecting Ol' Faithful. Bilge pump easily kept-up. As a matter of fact, I actually 'dressed' the shaft when there - I took a strip of 320 wet/dry sandpaper and, with the packing nut backed-out and the engine running in idle-forward, spent about 5-minutes to smooth-out the shaft where the packing rode. Worked like a charm!

Since then I've repacked and/or adjusted quite a few stuffing boxes - always in the water. Several of the boats I picked up needed stuffing box adjustments (used boats, not the new Nordhavns). Never quite figured out how a stuffing box can leak and also heat-up at same time, but it happens.

At any rate Hipocampus, I fully understand your apprehension. You know your limits and your comfort zone. Good reason to go dripless.

Peter
 
Just got off the phone with the yard. Decided to go with the Tides. Have enough exposed shaft can put on multiple replacements. Think that’s enough of a benefit to make that the best choice. Like the idea that wherever I am if a lip seal replacement is necessary I can do it myself and have the replacement in place.
 
One difference is that the wearing surface on the PYI is replaceable, as it is part of the seal assembly. The wear surface on the Tides is your prop shaft. It is replaceable too, but a bit more costly. The lip seal will eventually wear a groove in the shaft, could take a long time or not so long depending on the water.

I think people that have the PYI misting may have more than average engine movement. I've had a PYI that really was dripless and mistless. I have a Tides now that doesn't mist, but does drip a little for some reason.
 
Been following this interesting thread.

Seems like Tides vs PYI is a pick your poison affair.

The misting issue got my attention. However I throw this out in case something like it can work for someone as a retrofit project. Following is a picture showing the Helmsman 38 shaft seal, below deck plates but with an inspection window. Done that way I would expect (certainly hope) any mist is contained.

Helmsman used to spec Tides, and recently shifted to PYI. I don't know why.

1500x1000-HTL-38E-Gallery-P4250031.jpg
 
twistedtree said:
I have also had both and switched back to Tides on my current boat. I didn't care for the PYI/PSS device. I found the bellows tensioning to be very finicky, especially as the bellows aged and lost it's spring. And we are not talking about age past it's service life. I'm talking about 3-4 years old. I also had rust and pitting on the rotor. There was always a spit ring around the seal where it was slinging some amount of water. I was not impressed.


With Tides there is no bellows, not adjusting, and no rotor to rust pit or get stuck to the shaft. The seal is a lip seal just like is used on millions and millions of engines and other machinery throughout the world. And you can pre-install one or more replacement seals on the shaft allowing for replacement while in the water, and without removing the shaft.


Both of them need proper cooling, and will fail without it. If you draw water of the engine cooling system, be sure to draw it off upstream of the engine and gear cooler zincs. Otherwise you can end up with deteriorating zinc fragments getting into the feed hose to the seal and blocking water flow.
Click to expand...

I've had both and just switched back to Tides on our boat as well for some of the reasons above including the water slinging. Also, the there were reports of the bellows on the PYI/PSS prematurely drying and cracking. I have been told that this has been addressed and I also believe that the same issue was not present on the PRO version of the PYI/PSS seals.

Ultimately as others have said it's a 6 in one, half dozen in the other choice and I know multiple people happy on either side of the Tides/PYI PSS choice.

YMMV
-tozz
 
Not to hijack, but why do people not use Norscot seals? I have used them on a different boat that I still own, they are going on 20 years and I have never had a problem. Seals are lubricated with ATF, only down side is if a seal does leak it either leaks ATF into the water or sprays ATF into the boat, depending which seal leaks. There is a reservoir bottle for ATF replacement, and if it does spray into the boat, ATF is not corrosive unlike sea water. But more importantly, your boat can not sink as it can with PSS which I have on our other boat, but with a 3" shaft I am waiting to throw another boat buck plus labor to change out. Rudder has PSS on it also.
 
Hippocampus said:
Any thoughts about Lasdrop? Reluctant to go back to a traditional stuffing box even with the new style stuffing,
Click to expand...

I had Lasdrops on my GB42 for fourteen years with zero drips and zero maintenance, but when I eventually elected to replace them, I put on the more impressive, from a purely mechanical sturdiness prospective, PYIs and had zero issues there too. Now I have a single Tides which, like the other two brands, is water-cooled through the engine seawater cooling system. While it too is trouble-free, its lip seal design on what could become a less than nearly perfectly aligned allowing for leakage.
 
Stabi said:
Not to hijack, but why do people not use Norscot seals? I have used them on a different boat that I still own, they are going on 20 years and I have never had a problem. Seals are lubricated with ATF, only down side is if a seal does leak it either leaks ATF into the water or sprays ATF into the boat, depending which seal leaks. There is a reservoir bottle for ATF replacement, and if it does spray into the boat, ATF is not corrosive unlike sea water. But more importantly, your boat can not sink as it can with PSS which I have on our other boat, but with a 3" shaft I am waiting to throw another boat buck plus labor to change out. Rudder has PSS on it also.
Click to expand...

Those are really interesting. I hadn't heard of these and no boatyard I've been in has mentioned them. I might take a serious look at the next service interval for the Tides I just installed.

-tozz
 
I thought I would chime in with my 18 year experience using and another affirmative vote for, the little known Norscot shaft seal. Full disclosure first, I do not know anybody at Norscot, nor have I bought anything from them ever, just a happy owner of their product.

In 18 years and 5000 Hrs. I've replaced the 3" lip seals once, 9 years ago. 6 good quality (JM Clipper) lip seals cost about $45 CAD at my local seal shop. My port side seal started to weep ATF 2 months ago, no spraying, just a drop or 2 leak every 4 Hrs. while underway, nothing at rest. A credit card sized diaper lasts weeks. No salt water spray ever, which I always thought was the goal. I think the reason for the leak is that the rubber hose that attaches the seal carrier to the stern tube, now 25 years young has gotten stiff. Engines move on their mounts, this 10" long hose needs to flex, if it's stiff it may have taken the seal out. Hose replacement is likely overdue.

As with all things mechanical, a good understanding as to how and why they work is required to make them durable.

Lip seals generally require:

- The right size of and finish to, the shaft. No spiral grooves (even using 400 grit paper) are allowed as these spiral grooves tend to pump oil through the lip seal.
- To be lubricated with oil. Unfiltered seawater is a poor lubricant, it maybe a good coolant but coolant is not required as my seals run at about 100ºF. @ 950 RPM, or 750 Ft/Min. Both of these Temps. and speeds are well within the limits of common lip seals.
- To be installed intact, therefore use the proper seal installation sleeve.
- Keep the mounting hose flexible. Here I think I failed.
- Annually change the oil. This takes 5 Min. per side and cost you about a quart of ATF.
- If all else fails, read the instructions.

The only downside I can see is that you have to be on the hard to replace the seals, although this is just good practice, less scary and is not uncommon with other products. Understanding this, putting spare seals on the shaft serves no purpose.

I will haul and replace the seals, along with other scheduled things within a month or so and fully expect to find no grooved shaft at the seal location as they run submerged in oil. I doubt it's different this time.
 
Hi,

i have managed to fix a small leak with this method in my PSS seal. The leak is between the carbon and the flange of the shaft, in the video a quick and easy way to make it tight.


https://youtu.be/kXKA120ssOs

NBs
 
I only use the Volvo type rubber stuffing box. The Volvo Patent is long expired and the guys who made them for Volvo make the Orbitrade, my favoured version, Radiche do their version which is also very good plus Volvo still fit as OE and supply as spare parts.


My current one, in its fifth trouble and drip free year, is mounted 8 inches further forward for easier access on a 1/4 inch thick GRP exhaust pipe joiner.


The tech is simple. Put a poly bag up your arm, put in the sea and note how water pressure grips the poly bag to your arm. Water pressure applies the two long and soft sealing lips to the rotating shaft. The rear is water lubricated, the forward one by grease.


Annual greasing, if fitted - as mine is with a vent tube - self bleeding after launching or drying out.


If the available sizes fit your vessel, worth looking at.
 
Another vote for tides. I was told that if you cruise in waters with snow melt (Alaska), the particulates in the melted snow will act like sandpaper on your spinning shaft and will wear down the shaft seal. The idea of the extra lip seals pre mounted on the shaft for easy replacement, really appealed to me. I also installed a flow meter on the cooling hose from the engine along with a cross over from the second engine. Of course all this was done after melting a shaft seal due to blockage from one engine.
 
Hippocampus said:
Always had PYI devices. Only trouble I ever had was need to add cooling water to the latest version. As part of routine maintenance noted evidence it was heating.
As part of the survey findings on our new to us boat it was mentioned there was a slight leak on the PSS. I like perfection on key systems so asked yard to deal with it as we’re in a different state than the boat at present. They said they couldn’t move it. Couldn’t slide it at all so after trying heat, solvents and brute force used a cutting wheel and cut it off.
They want to replace with it with the Tides device. Never had one in the past.

What’s the +/- of Tides v PSS? Lip seal (no moving parts) v aligned plates (moving parts and pressure in bellows).
Click to expand...

Feeling completely ignorant here. What's PYI, PSS, lip seal????
 
billdomb said:
Feeling completely ignorant here. What's PYI, PSS, lip seal????
Click to expand...
Not going to go into the design of the two systems, only the basic differences. I've had both systems.

PYI and PSS are the same thing. They seal by compressing on the shaft and locking in place with a set screw. You have to take the boat out of the water to replace if they go bad. A common failure is not having a secondary locking mechanism if the set screw loosens on the shaft (a simple hose clamp would do the trick).

Tides uses a lip seal to keep the water out (no compression needed). You can replace the seal with the boat in the water. The spare seals have to be pre mounted on the shaft when the boat is out of the water. I have two spares ready to go in case the lip seal starts to leak.

Both need water to lubricate the sealing system. Either from the engine, or just from the water that comes up the shaft seal, but you need a above water line hose coming from the seal so you don't get an air lock. I don't recommend this as I melted a brand new shaft seal following the instructions from the manufacturer.

I would highly recommend a water flow meter to verify water flow from the cooling water coming from the engine. It only takes a short time to melt the shaft seal if the cooling water line becomes obstructed. I also have a crossover from my other engine as well. I'm pretty sure both systems offer this option (two cooling water ports).
 
billdomb said:
Feeling completely ignorant here. What's PYI, PSS, lip seal????
Click to expand...
Two pics attached. Green background is the PYI style. It has two main components - a stationary bellows that attaches to the stern tube. And a collar that attaches to the prop shaft and turns along with the shaft. The picture shows the two parts spread apart, but in usage, they are pressed together - a spring in the bellows provides compression and forms a seal between the mating surface of the bellows assembly and the collar assembly.

The second picture shows a lipseal style dripless stuffing box. A spare lipseal is shown to the right in the picture. A lipseal is a generic name for a style of flexible seal that is mounted stationary in a housing with a shaft passing through the circular opening. The shaft/seal interface is close tolerance and prevents fluid from passing while the shaft turns. A traditional stuffing box with rope-like packing is essentially a crude form of lipseal. Lipseals are commonly used in automotive engines where the crankshaft passes outside the block to connect to the transmission. If you've ever heard the phrase "leaking mainseal," it's this lipseal that has deformed. A spare lipseal can be pre-loaded on the shaft prior to final assembly.

Hope this helps

Peter

Screenshot_20220409-044737_DuckDuckGo.jpg754965116.jpg
 
Another difference is need for lubrication. On a slow turning shaft (think sailboat) used intermittently cooling water isn’t key with the PYI device. To the point it’s sometimes omitted with small engines. Given the seal is between two plates condition of the shaft isn’t critical. With a lip seal the shaft under the spot where the seal is placed must be totally smooth and round. The seal needs cooling. Downsides to the PSS is needs to be out of water to fully service. They need to be “burped” before use. Failure to do that will leave air inside the bellows. Air is a good insulator so heat will be retained.Lubrication as designed may not occur. You have a hole in your boat. Size is the area between shaft and shaft log. Given the PSS is dependent upon the flexible bellows, all clamps and the rotating plate being in immediate proximity to the stationary plate there’s more potential points of failure. Failure can sink your boat. With the tides lip seal that piece is much more substantial and isn’t under compression. No bellows. Neither is there a plate that can slide up the shaft. Fewer failure points. However the lip seal can leak. Even so said to have a lower risk of catastrophic failure and lower risk of sinking the boat. For both dirt, abrasive grit, salt, sand in the cooling water can lead to premature wear. The lip seal maybe more prone to this.

This time went with the Tides. Don’t have a strong opinion about either. But at present my thinking is about the same as TT. We’ll see….
 
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Personally, I'm a fan of just sticking with a conventional stuffing box with good, modern packing. Less ways to fail that you can't resolve in a few minutes with the boat in the water, and with good packing, they just work pretty well and don't really drip that much. Yes, some worry about water spray getting on other components, but that can be an issue with dripless seals as well. Good design dictates that you'd place components or add a shield to contain the spray.
 
Hippocampus - my comments here speaks to the reliability of the PYI PSS seal. I just installed the PSS maintenance kit (bellows, hose clamps, rotor o-rings, and new allen lock screws. I'm the original owner of this 2006 Nordic Tug, so I was going into the 17th YEAR (!) with the original PSS seal. The original seal worked perfectly. Never any leaks, and the only maintenance was occasional visual inspection, check hose clamps, and an occasional wipe of 3M 303 on the bellows. While PSS recommends replacement every 6 years (now 10 years with newer bellows), when questioning a replacement, boat yard manager and even PSS reps at boat shows always came back with... "if it ain't broke, don't fix it". I was just getting antsy. 2,400 hours on the engine.

Regarding your comment on not being able to remove SS rotor, your boat yard probably didn't realize there are 2 allen screws threaded in with Permatex threadlock. The first is to lock the rotor to the shaft, and the second is to lock the first set of allen screws. Apparently they had no PSS experience.

I will admit that the installation of a new PSS or a maintenance kit can be problematic, but that was unique to this Nordic Tug model. With a double-taper shaft, and a black water tank outlet hose barb 6" behind the coupler, I couldn't use a coupler puller. Went "old-school" with longer bolts and a small socket to pop the coupler off the shaft. Popped right off just snugging up 3 bolts.
 

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DNT99611 said:
So if you have a keel cooled boat how do you about getting the cooling water for the seals?[/QUOTE
Wow! Never considered that! Probably have to install a small raw water pump just for that purpose.
Click to expand...
 
I installed the tide seals on my last 2 boats. Never had one drop of water leak by. One was on 6 seasons, one was on 15 seasons.
And if it ever wears a slight "groove" in the shaft (which would take a very long time) you can simply cut the hose a little shorter and seal on a virgin section of shaft.
 
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