On May 26, 1998, then the largest cruise ship in the world, 109,000 GT Grand Princess, made her inaugural voyage with a 12 night cruise from Barcelona to Istanbul. Unlike contemporary cruise vessels at the time, she was fitted with seawater lubricated propeller shaft bearings. Due to her size, risk studies completed by the technical team at Princess Cruises/P&O, in conjunction with the shipbuilder, Fincantieri, indicated that few drydocks could take a vessel of this size. Any unscheduled drydocking to repair a stern tube seal leaking oil could result in substantial financial losses, pollution risks and long transit to and from a suitably sized drydock. The recommendation: seawater lubricated propeller shaft bearings.
The prudence of that decision has been clearly demonstrated through almost 13 years in service. Grand Princess has not had any unscheduled drydockings due to stern tube oil leakage - there is no aft seal to leak and the bearings are lubricated with seawater, not oil.
In April 2011, Grand Princess completed a scheduled drydocking at Grand Bahamas Shipyard for extensive upgrades and modifications. Bearing clearances in the original Thordon COMPAC strut and stern tube bearings were checked and indicated that the bearing wear was well within acceptable limits – please see chart. Also of financial importance, the bearing design allows for their removal, inspection and re-install with the shaft still in place. The two propeller shafts have never been withdrawn since their installation in 1998.
The ship owner, Carnival Corporation, has continued with that 1998 decision and now has 14 Carnival Corp.-owned cruise ships fitted with Thordon COMPAC seawater lubricated propeller shaft bearings and more COMPAC bearing systems on order for two future newbuilds.
Thordon Bearings Inc. designs and manufactures a complete range of non-polluting propeller shaft, rudder and shaftline products for the global marine market. Recognized internationally for superior performance in marine applications, Thordon Bearings has a worldwide customer service network in over 100 countries.
Source: http://www.thordonbearings.com