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Old 03-31-2022, 03:17 PM   #1
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Tides v PSS

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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Old 03-31-2022, 03:58 PM   #2
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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
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Old 03-31-2022, 04:53 PM   #3
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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
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Old 03-31-2022, 06:11 PM   #4
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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.
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Old 04-01-2022, 06:18 AM   #5
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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.

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Old 04-01-2022, 08:22 AM   #6
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Any thoughts about Lasdrop? Reluctant to go back to a traditional stuffing box even with the new style stuffing,
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Old 04-01-2022, 08:37 AM   #7
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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
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Old 04-01-2022, 08:45 AM   #8
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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.
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Old 04-01-2022, 09:35 AM   #9
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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.
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Old 04-01-2022, 10:03 AM   #10
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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
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Old 04-01-2022, 10:56 AM   #11
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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.
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Old 04-01-2022, 11:04 AM   #12
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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.
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Old 04-01-2022, 11:22 AM   #13
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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.

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Old 04-01-2022, 04:00 PM   #14
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Quote:
Originally Posted by twistedtree View Post
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'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
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Old 04-01-2022, 06:00 PM   #15
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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.
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Old 04-01-2022, 07:34 PM   #16
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Originally Posted by Hippocampus View Post
Any thoughts about Lasdrop? Reluctant to go back to a traditional stuffing box even with the new style stuffing,
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.
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Old 04-01-2022, 08:55 PM   #17
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Originally Posted by Stabi View Post
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.
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.

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Old 04-02-2022, 08:52 PM   #18
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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.
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Old 04-03-2022, 03:40 AM   #19
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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
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Old 04-03-2022, 07:26 AM   #20
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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.
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