When the first American-made lake freighter built in more than 35 years launched in Sturgeon Bay, Wis., last year, the 639-foot ship was outfitted for the future. The M/V Mark W. Barker’s larger hatch openings and spacious flat-bottomed hold meant that, unlike most freighters transporting iron ore and limestone on this route, it could hold unusual cargo — in particular, wind turbine blades.