PYI Packless Sealing Systems

[LuckyLady]

PYI Inc. is a superior manufacturer and distributor of high quality marine and boat products with over 25 years service in the industry. Of significant interest to commercial mariners are products that reduce maintenance and down time. PYI showcases the internationally recognized PSS Shaft Seal, distributes R&D engine mounts, floor/panel anchors and other marine products.

Packless Sealing System

Kvichak The PSS (Packless Sealing System) Shaft Seal offers a trouble-free solution for stuffing box replacement in what is often a hard to service area. PYI manufactures PSS shaft seals for 3/4-inch to 6-inch shafts. Metric sized shaft seals to fit 22-mm to 95-mm shafts, with custom sizes up to 140 mm. More than 60 boatbuilding manufacturers use PYI propeller shaft seals as standard equipment during factory installation, including: Nichols Brothers Boat Builders, Textron’s USCG 47-foot MLB, Kvichak Marine, Pacific Seacraft and Northern Marine.

Shaftseal The PSS mechanical propeller shaft seal uses a stationary carbon flange in direct contact with a stainless steel rotor that turns with the prop shaft. Water pressure and the Nitrile bellows produce constant contact between the carbon flange and the stainless steel ring. The result is a reduced maintenance, 100 percent watertight seal unaffected by vibrations or engine motion. PYI’s PSS Shaft Seals are made in the USA with a three-year factory guarantee.


Flange

1. HIGH-DENSITY CARBON/GRAPHITE FLANGE
This space age composite is machined to shape. The face is then lapped to four light bands. Once installed and operational, the carbon/graphite face will actually polish the stainless steel rotor face during the initial minutes of operation. This polishing process ensures a perfect seal and eliminates the need for a spray guard. The high-density carbon/graphite composite greatly increases its resistance to impact and wear. At a maximum operating temperature of 500° F, the carbon guards against any overheating situation unlike other seals using plastic derivatives. The carbon/graphite flange should never need replacing under normal operation conditions.

2. DOUBLE O-RINGS
The Nitrile O-rings are fit inside the stainless steel rotor to guarantee alignment and seal of the rotor to propeller shaft. Nitrile is used for its superior resistance to petroleum products, temperature variations and resistance to tearing. These O-rings are stationary and do not wear.

3. STAINLESS STEEL ROTOR
The one-piece stainless steel (Type 316) rotor is slid down and secured to the propeller shaft with double set screws. Computer controlled lathes maintain precision tolerances. After machining, the rotors are passivated to military specifications for maximum corrosion resistance. The stainless steel rotor should never need replacing under normal operating conditions.

4. DOUBLE ALLEN HEAD SET SCREWS
Allen head set screws with cupped ends (to prevent damage to shaft) are threaded into the rotor and secured to the propeller shaft. A second set screw is then threaded into each hole to secure the first screw and to prevent it from possibly backing out. Set screws are treated with a Dri-Loc 204.

5. DOUBLE HOSE CLAMPS
Two stainless steel hose clamps are used to secure the bellow at both the stern tube and flange ends.

6. BELLOW
Bellow is resistant to petroleum-based products and set retention. It provides the best combination of durability, strength and elasticity. The stern tube end of the bellow is available in 1/4-inch increments. Both shaft and stern tube diameters are necessary when ordering.

http://www.pyiinc.com/index.php?sect...tion=main&sn=1

[Fritz]

These seem a bit less expensive than the Tides brand. Anybody have any experience with this brand?

[clt_capt]

Yes - I had them on my Phoenix for a few years before I sold it.

Once they were installed and adjusted, they were great.

[JD5652]

Fritz-

I have them on my boat and no problems in almost four years. One thing to note about ANY dripless packing system though is that they MUST be checked and maintained. If the boot wears, becomes brittle or is in ANY way suspect, it needs to be replaced. This requires hauling the boat and pulling the shafts. If the boot cracks or breaks, then you'll have water coming into the bilge.

One other thing to keep a check on is that the PYI brand requires raw water for cooling. This is accomplished by providing raw water from somewhere in the raw water cooling system to the plastic barb on the packing unit itself. This line must be checked to ensure it does not clog and prevent cooling water flow to the seal. At one point I found remnants of a zinc that had clogged my cooling line to the seal.

All in all, I have no complaints, but some people think that dripless packing means "maintenance free" packing and that is simply not the case.

[Fritz]

Originally Posted by JD5652

Fritz-

I have them on my boat and no problems in almost four years. One thing to note about ANY dripless packing system though is that they MUST be checked and maintained. If the boot wears, becomes brittle or is in ANY way suspect, it needs to be replaced. This requires hauling the boat and pulling the shafts. If the boot cracks or breaks, then you'll have water coming into the bilge.

One other thing to keep a check on is that the PYI brand requires raw water for cooling. This is accomplished by providing raw water from somewhere in the raw water cooling system to the plastic barb on the packing unit itself. This line must be checked to ensure it does not clog and prevent cooling water flow to the seal. At one point I found remnants of a zinc that had clogged my cooling line to the seal.

All in all, I have no complaints, but some people think that dripless packing means "maintenance free" packing and that is simply not the case.

Thanks JD. I have had the Tides brand on my last two boats and loved them. These work on the same principal, but seem to be less expensive. You are correct about the raw water cooling. Typically, a hose for raw water is connected to a nipple / fitting on the engine's raw water pump, but you should install a cross over T between hoses for each shaft seal to help prevent seal damage, if you loose one engine.

[JD5652]

Originally Posted by Fritz

.... but you should install a cross over T between hoses for each shaft seal to help prevent seal damage, if you loose one engine.

Fritz-

Very good point!

However, some transmissions (such as mine) can not be allowed to free wheel if the engine is not running. I have Capitols HE11200 that can not be free wheeled due to the need for pressurized lubrication of the clutches. If I lose an engine, then I have to lock the shaft on the non-operating engine. Some of the newer set-ups can be free wheeled. It's amazing how many people are not sure if their engine/trannies can be free wheeled or not.

[Fritz]

Originally Posted by JD5652

Fritz-

Very good point!

However, some transmissions (such as mine) can not be allowed to free wheel if the engine is not running. I have Capitols HE11200 that can not be free wheeled due to the need for pressurized lubrication of the clutches. If I lose an engine, then I have to lock the shaft on the non-operating engine. Some of the newer set-ups can be free wheeled. It's amazing how many people are not sure if their engine/trannies can be free wheeled or not.

If you loose an engine, you will blow the shaft seal within a minute or two wihout the cross over T depending on speed. Been there and done that. Speaking of which, Tides allows for a spare seal kit to mounted on the shaft between the log & coupling. Do these type provide for a spare as well?

[JD5652]

Originally Posted by Fritz

Tides allows for a spare seal kit to mounted on the shaft between the log & coupling. Do these type provide for a spare as well?

To my knowledge. PYI does not have a provision for a mounted spare seal kit.

Does anyone have any experience with Lasdrop seals? I was looking at them as a possible alternate to rebuilding my PYI's.

http://lasdrop.com/

[mad mike]

I have a pyi seal on my boat it works great.no there isnt a way for a spare seal the main seal is mechanical not like a lip seal that can rip also dealt with pyi building a radar mount superb service! I know for a fact if there is a problem they will take care of it in a blink of an eye!

[Capt.Troy Crane]

JD,
I have a set of the Lasdrop on my Bertram, put them on about four years ago. I like them because there is no boot to dry rot and fail. Once installed and adjusted they are ready to go.

You are correct in saying that you need to keep an eye on them like anything else and I second the recomendation of the cross over for the water line as Fritz mentioned. It will save you a lot of trouble in the long run.

Good luck,
Troy