After nine years of operation in the harsh, abrasive waters of Alaska’s Yukon River, aboard Inland Barge Service’s push boat Ramona, Thordon Bearings’ RiverTough water-lubricated tail-shaft bearing system has emerged completely free of wear and tear, according tot the manufacturer. The performance of the RiverTough bearings in waters renowned for their high content of gritty glacial silt came to light when the 16-meter workboat’s cracked struts underwent repair in dry-dock. Charles Hnilicka, the owner of Inland Barge Service Inc, said, “In the spring of 2011 we were doing some hot work on one of the struts and decided to change the bearing since everything was apart. We didn't have to and could have reinstalled the original bearing after the hot work, but we had a spare set. “When we took it out, the RiverTough bearing and sleeves had no appreciable wear and tear, which was amazing considering the environment in which the Ramona operates.” The 1971-built push boat provides an invaluable service delivering freight and consumer goods to communities along the Yukon River and its tributaries. These shallow waters, usually only navigable between May and October, are fed by rain and glacial melt containing highly abrasive silt and ground rocks, called glacial till, that can severely damage other propeller shaft systems. Since 2003, when Inland Barges Services replaced the single-screw Ramona’s rubber bearings, Thordon’s polymer system has undertaken over 2000 hours of operation per year in some very abrasive environments. “I haven't seen anything like it,” Hnilicka said. “When we used rubber bearings we were lucky to get a full operational season out of them before they needed replacing.” Scott Groves, Thordon Bearings’ Business Development Manager, said, “We have data from workboats operating on the Mississippi showing typical RiverTough wear rates of 0.075 to 0.100 millimeters in 6,000 to 7,000 hours of annual use, but this is the first time we have received data from a vessel operating in the high north. The feedback from Inland Barge Services provides clear evidence of RiverTough’s superior wear life in very abrasive water conditions. They routinely outlast rubber bearings by a factor of two or more.” Todd Terry, President of Pacific Marine Equipment (PME), Thordon Bearings’ Seattle-based distributor, said Inland Barge Service, Inc is among a growing number of workboat and small craft operators to covert from rubber tail-shaft bearings to the RiverTough solution. “In 2001, we supplied the water-lubricated bearing system to HamiltonJet’s Yukon Queen. The vessel ran from 2001 to around 2010 when it was sold and left the river. HamiltonJet reported that the RiverTough bearing worked exceedingly well in this application. Since then, we have supplied Interlake Steamships, Riverway Transport, American Commercial Lines, Ingram Barge Line, Blessey Marine Services and Eckstein Marine.” McAsphalt Marine Transportation is the latest owner to opt for the RiverTough solution and Thordon Bearings will supply water-lubricated bearings and Nickel Chrome Boron-coated stainless steel liners for a twin-screw articulated push barge operating in the Great Lakes waterway system. The bearings will be designed for 365 millimeter shaft diameters.