Stern Tube Seals and Bearings
Water-lubricated and oil-lubricated stern tube arrangements, seals, bearings and the sealing rings and liners that go with them.
Features
- Water-lubricated arrangements use a composite or rubber bearing and accept a controlled water flow; oil-lubricated arrangements run in an oil-filled tube with seals at both ends.
- Changing between the two types means changing the bearing, the seals and usually the shaft's surface condition at the sealing position.
- Seal wear shows as ingress rather than as noise, so bilge water in the shaft compartment is the symptom to act on.
- Shaft liners and sealing rings are consumable and are best held as onboard spares, since a failure means the vessel stops.
- Alignment and shaft run-out affect seal life directly, which is why a repeated seal failure is investigated as an alignment question.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Arrangement | water lubricated / oil lubricated | decides bearing, seal and maintenance regime | |
| Shaft diameter at seal | 70 - 220 | mm | the identifying dimension for the seal set |
| Bearing material | composite / rubber / white metal | tied to the lubrication arrangement | |
| Permissible run-out | 0.05 - 0.15 | mm | run-out beyond this shortens seal life sharply |
| Spare set held on board | yes, one complete set | a seal failure means the vessel stops until it is replaced |