Green-hulled tug inching up the gray river this morning. Two-story green-and-white wheelhouse set twenty feet back on the deck, another eight feet of deck behind it. White-painted steel rails surrounding the front deck, wrapping a pile of bright orange warning buoys. On the rear deck, in a black sweater and black pants, a man practicing karate kicks. As the tug approaches the pilings, he sprints up into the wheelhouse. Tug veers slowly left, into the river's center channel, heads straight again. The man descends the stairs and goes back to his kick practice. The tug chugs out of sight.