Joint Mécanique PSS logo

PSS · Shaft Seals

The PSS Shaft Seal is the #1 selling marine mechanical seal worldwide and is installed as standard equipment by many of the worlds most reputable boat builders and boatyards.

The PSS Shaft Seal is also recognized as the premiere retrofit (aftermarket) seal on the world market. Boat builders and boatyards recognize the advantages and value of installing the PSS as it eliminates the maintenance, constant adjustment, and cost associated with traditional packing type glands. Aside from these benefits, the PSS Shaft Seal helps to eliminate water in the bilge (100% watertight) and wear to the propeller shaft.

The PSS Shaft Seal can be easily retrofitted and is available for shafts ranging from 3/4” to 8” (20mm to 203mm).



Fits 32mm to 95mm shaft
(1-1/4" to 3-3/4")

PSS type A

Fits 20mm to 95mm shafts
(3/4" to 3-3/4")

PSS type B

Fits 100mm to 150mm shaft
(4" to 6")

PSS type C

Fits 165 mm to 203mm shaft
(6-1/2" to 8")

PSS Rudder Post Seals

Fits 32mm to 150mm
(1-1/4" to 6")

Flange & Bladder System

Fits 63.5mm to 150mm
(2-1/2" to 6")


The PSS Shaft Seal is a mechanical face seal. The sealing surface is created between the flat surfaces of the rotating stainless-steel rotor and the stationary carbon flange. The stationary carbon flange is attached to the front side of the bellow with hose clamps, and the back end of the bellow fits over the Stern tube and is secured with hose clamps. The stainless-steel rotor is fit on the shaft in front of the carbon flange. The stainless-steel rotor is used to compress the bellow before the rotor is secured to the shaft with set-screws.
This compression (pre-load) maintains constant contact between the two flat faces of the stainless-steel rotor and carbon flange, allowing the PSS to compensate for the variable fore and aft movement due to propeller thrust. The carbon flange is over-bored to the shaft diameter allowing it to “float” around the shaft and thus compensate for most misalignment and vibration problems. The stainless-steel rotor is sealed to the shaft by two O-rings that are recessed into the bore of the collar. These O-rings rotate with the shaft and stainless-steel rotor and do not experience wear during operation.

How works PSS shaft seal



A stainless steel rotor that is slid down the shaft and secured with set screws at 90 degrees for maximum holding power.


The convoluted bellow clamps onto the stern tube (shaft log) and attaches onto the carbon stator.

Joint mécanique PSS de type A

Carbon Stator

A carbon stator is connected to the rubber below and 'floats' around the shaft. The face of the carbon is finished to a flatness of 4 helium light bands and provides a water tight seal when pressed against the stainless steel rotor.


The PSS Shaft Seal has been thoroughly tested and approved by these certifications.
RINA certification


Bureau Véritas certification





What is a PSS Shaft Seal ?

Removing the shaft coupling



PSS Shaft Seals are available around the world. Use the map below to find the nearest PSS Shaft Seal dealer to you.

TOP elit. mattis neque. vulputate, mattis lectus ut ut id mi, sem,