Moving 30 barges at once takes the sure hand of a tugboat pilot who knows how to maneuver a flotilla through the twists and turns of the Mississippi River. Lashed together, three across and 10 long, the barges cover more than twice the surface area of a modern aircraft carrier. Most would agree that the best river pilots are artisans, deeply skilled in methods to meet the challenges of that particular job. Equally skilled, however, are the tugboat captains in a crowded ocean harbor…