Lakeboat, from an early play by David Mamet - he wrote it in the early 1970s, based on his experiences as a college student doing a summer internship on a steel freighter in the Great Lakes - is brought to the screen awkwardly but ardently by Mamet-actor supreme Joe Mantegna in his feature-directing debut. There are updated references, including one to - yikes! - Steven Seagal. Still, the piece is a theatrical curio, but no less fascinating for that as the shipmates reveal their dreams and…