The tank barge Greenstone II, the first vessel to be built by Superior’s Fraser Shipyards in nearly 40 years, is tentatively scheduled to depart the Port of Duluth-Superior on Monday, May 24, the Duluth Seaway Port Authority reported today. Fraser Shipyard floated the Greenstone II at its dry dock today (May 21), and has scheduled the Marine Tech, Duluth, tug Miss Laura to escort the vessel to Houghton, Mich. The Greenstone II is a double-hulled fuel barge that will operate between Houghton and Isle Royale National Park, replacing the single hulled barge Greenstone that was retired last year. Fraser Shipyards, whose predecessors date back 113-years, is the only remaining major American shipyard and dry dock operation on the western end of the Great Lakes.