Coast Guard Cutter Mackinaw, home-ported in Cheboygan, Mich., passes port-to-port with the tug Joyce L. VanEnkevort and its barge the Great Lakes Trader in the Stribling Dike on the St. Mary's River Jan. 10, 2014. The crew of the Mackinaw was conducting ice-breaking operations, including leading a five-ship convoy up the lower part of the river.