CLEVELAND, Ohio -- U.S. shipping companies are spending $97 million this winter to maintain and modernize lakers at shipyards throughout the Great Lakes.

Each ship hauls cargo more than 70,000 miles during the 10-month season, according to the Lake Carriers Association. The Soo locks between Lake Huron and Lake Superior closed this month. Now ships and crews get to recoup before the 2020 season begins March 25.

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More than 1,000 engineers, welders, pipe-fitters, mechanics and electricians are working on freshwaer freighters, also known as lakers, in Ashtabula and Toledo; Detroit and Ludington, Michigan; Milwaukee, Superior and Sturgeon Bay, Wisconsin; Erie, Pennsylvania.

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Winter work includes the steel renewal, installation of advanced electronic navigation systems, and replacement of safety equipment such as lifeboats, according to the Lake Carriers Association, which moves 90 million tons of iron ore, stone, coal, cement, and other dry bulk materials. The self-unloading capability on lakers is unique, used to unload up to 75,000 tons of cargo in less than 12 hours.

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