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Top 10 reasons to use Thordon seawater lubricated propeller shaft bearings in your ship






  1. Long, predictable bearing wear life and Guaranteed for 15 Years for all Classed newbuildings
  2. Proven in commercial ships – Over 600 ships use Thordon seawater lubricated propeller shaft bearings
  3. Thordon stern tube bearings are lubricated with Seawater - an EAL (Environmentally Acceptable Lubricant) and it is FREE!
  4. U.S. EPA recommends that all new build vessel operators endeavor to use seawater-based systems for their stern tube lubrication to eliminate the discharge of oil from these interfaces to the aquatic environment– See U.S. Vessel General Permit (Section 2.2.9)
  5. Never worry about oil leakage from a damaged aft seal as there is no oil used… so no possibility of  pollution and fines
  6. No risk of costly shaft seal repairs from seal repair companies that charge US$150,000 to US$300,000 per repair
  7. No possibility of stern tube oil discharges meaning zero  impact on seabirds and aquatic life (compared to mineral and biodegradable oils)  
  8. Survivability -  Thordon bearings’ non catastrophic failure mode allows vessel to get back to port without being towed
  9. Lower operating costs – no aft seal maintenance, no oil, no disposal of oil
  10. Technically equivalent to oil lubricated propeller shaft bearings – DNV GL, Lloyd’s Register, Bureau Veritas, and China Classification Society recently revised their rules allowing the shaft to remain in place if certain monitoring conditions are met.


COMPAC seawater lubricated bearings are a benefit to us all












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.

Closeup view of COMPAC bearing with single keyThe 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 a self-contained pumping unit which removes suspended solids with a specific gravity of 1.2 or higher and greater than 80 microns (0.003”). 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:Vessel in drydock being installed with COMPAC bearings

  • 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