Thordon Bearings Inc.

- Blue Water Propeller Shaft Bearing Systems



The COMPAC bearing system uses seawater as the lubrication medium in place of oil. Seawater is taken from the sea, pumped through non-metallic COMPAC propeller shaft bearings and returned to the sea. To ensure that abrasives are removed from the seawater supply, a Thordon Water Quality Package is used.  Use of seawater lubricated bearings eliminates the aft seal, as well as the storage, sampling and disposal of oil. Thordon currently offers an industry leading 15-year bearing wear life guarantee on COMPAC. The COMPAC shaft bearing system is currently installed on 600 vessels worldwide.

The Thordon COMPAC bearing is an elastomeric polymer alloy designed in a 2:1 L/D configuration in the AFT bearing.  To promote early formation of a hydrodynamic film between the shaft and bearing, the lower (loaded) portion of the bearing is smooth, while the upper half of the bearing incorporates grooves for flow of the water lubricant/coolant. The COMPAC system typically includes COMPAC bearings, shaft liners, a Water Quality Package, ThorShield shaft coating and a forward seal.

The Thordon Water Quality Package is designed to supply seawater to the propeller shaft bearings for lubrication and cooling at a minimum flow rate of 0.15 litre/minute/mm (1 US gallon/minute/inch) of shaft diameter and to condition the seawater by removing suspended solids larger than 100 microns (0.004” ) and with a specific gravity of 1.2 or higher; separation to 80 microns (0.003”) is achievable using the 75-150 l/min (20-40 GPM) unit. As water enters the forward seal, it flows through the COMPAC bearings and exits at the stern. Flow rate is monitored by low flow alarms.

The ThorShield propeller shaft coating system provides corrosion protection against seawater. This toughened, 2-part epoxy coating is up to nine times more flexible than existing shaft coating products.

With increasingly stringent environmental regulations, Thordon’s seawater lubricated propeller shaft bearings are replacing oil-lubricated, metal bearings.


Proven in the toughest marine environments since 1983, Thordon bearings offer:

  • Zero pollution risk (no oil required)
  • 15-Year Wear Life Guarantee for COMPAC in bluewater  operation*
  • Turnkey engineering and installation support
  • Easy fitting
  • Reduced seal maintenance costs
  • Inspections without shaft withdrawal
  • Resistance to shock and edge loading
  • Survivability (our non-catastrophic failure mode allows ship to get to port)
  • Global availability

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