It is more than twenty years since Société des Traversiers du Québec (STQ) retrofitted Thordon Bearings’ water lubricated propeller shaft bearings to the double-ended ferries Armand-Imbeau and Jos-Dechênes, as part of an ambitious vessel modification project.
Since then, Thordon water lubricated bearings are the only propeller shaft bearings the Canadian ferry operator will specify. This, attests Stéphane Caouette, Director Maritime Services, STQ, is because “they are better for the environment and longer lasting than any oil-lubricated system. The COMPAC water lubricated propeller shaft bearing is the only bearing system we have on our vessels operating with conventional propeller shafts.”
It was in 1996 that STQ decided to lengthen each of the ferries by 19.2m (63ft) to increase passenger and vehicle capacity. The project required an upgrading of the original engines to deliver greater power for a cruising speed of 12kts and modifications to the shaft to accommodate a water lubricated arrangement. The original oil lubricated stern tube bearings were replaced with a 279.5mm (11”) COMPAC bearing aft and a larger 299.5mm (11.8”) COMPAC bearing sited fwd.
“We changed the bearings for two reasons,” recalled Caouette: “environmental and economic. We are a member of Green Marine / L’Alliance verte, so found the Thordon system fits in with our goal of protecting the marine environment.”
“Although we have not carried out any specific operational cost comparisons between the two different systems, we have found the water lubricated arrangement has helped reduce our maintenance spend.”
The cost saving is largely due to the avoidance of emergency drydocking and regular aft seal replacements which frequently impair the oil lubricated system.
Commenting on STQ’s decision to only use water lubricated propeller shafts, Scott Groves, Business Development Manager, Thordon Bearings, said: “Over the last few years, STQ has gradually renewed or replaced its fleet, with all of the vessels now operating COMPAC water lubricated propeller shaft bearings. This is testament to the performance, reliability and robustness of the owner’s first COMPAC installation, more than twenty years ago.”