Carrying people and goods across rivers by ferryboat is a two-century old form of transportation that existed long before modern bridges. But for Clackamas County, Ore., three to four hundred automobiles use the county-owned Canby Ferry to cross the Willamette River every day, seven days a week. Annually, the ferry saves a long ride across the Canby town bridge for about 100,000 drivers taking business or pleasure trips to nearby wine country. To ensure the 300-foot crossing over the Willamette River goes smoothly and quietly, the ferryboat was recently upgraded to include two new, very modern electric motors – each of which is powered by a Danfoss variable frequency drive.
Christened the M.J. Lee II, the 84-foot, steel-hulled, double-ended craft received the new variable frequency drives when it was completely refurbished in 2013. Before that, the ferry has a long history — a small wooden ferryboat was first put into service in 1914, and was then replaced in 1953 with a steel-hulled vessel christened the M.J. Lee. Following a retrofit in June 1997, the 160,000-pound vessel was rechristened the M.J. Lee II, with a capacity for 43 passengers and six automobiles.
Until the 2013 retrofit, the M.J. Lee II was powered by an electric-over-hydraulic propulsion system. "The goal of the retrofit was to create a quieter, more efficient system," says Matt Bradford, general manager of Harbormaster Marine, the firm that produced the propulsion system for the recent retrofit. "The electric motors in the old system powered hydraulic pumps that drove a hydraulic motor on each propeller shaft. Because the drives are mounted amidships on each side of the vessel, hydraulic lines filled with pulsating fluid were in contact with the steel hull, which was very noisy for workers, passengers, and the local community.
"In addition to the noise, there were environmental concerns. The county wanted to reduce the need for frequent hydraulic fluid leak repairs and the risk of an oil spill."