Where does the sealing happen?

The mechanical face-seal approach

In a PSS, the rotating metal rotor meets a stationary carbon face. The working contact is across those flat faces. A flexible bellows maintains the installed contact pressure, while O-rings seal the rotor to the shaft.

Picture a ring turning against another ring. The quality and condition of their meeting surfaces, together with the correct setup and cooling, matter to the result.

The lip-seal approach

A lip seal places its sealing edge around the shaft. The shaft rotates within that edge, so the condition of the shaft at the contact area is important. The housing and connecting arrangement vary between manufacturers.

Tides SureSeal combines a replaceable lip with an integral alignment bearing and an articulating hose. GLIDE GMSS uses its own double lip arrangement and integrated bearing surface. They share a broad category but are distinct products with their own instructions.

Why the distinction helps in a refit

When looking at a face seal, ask about face condition, bellows setup, rotor retention and cooling. When looking at a lip seal, also identify the shaft surface on which the lip will run and how the manufacturer allows it to be serviced.

These questions help explain why the same shaft diameter can lead to different recommendations. The available shaft surface, access and space may be just as important as the dimension printed on the box.

Service is part of the choice

Different designs lead to different service jobs. PSS publishes bellows replacement guidance and supplies maintenance kits. Tides offers an advance-installed spare carrier that can support lip replacement afloat.

Consider when you normally haul out, who maintains the vessel and how easily the seal can be inspected. A service feature only helps when the installation and the necessary preparation allow you to use it.

Choose a product, not a category alone

A face seal is not an automatic cure for an unsuitable installation, and a lip seal is not automatically the wrong choice. Compare the complete product against the boat, then follow its instructions.

Luxfords supplies PSS and can help you understand where the Type A, PRO or larger Type B family fits your enquiry. Start with exact shaft and stern-tube measurements, clear photographs and the reason for the proposed change.

• Identify the actual sealing interface.
• Check the installation requirements.
• Understand the planned service procedure.
• Confirm the exact product for your vessel.