The cutter Mackinaw is one of 31 vessels Marinette Marine Corp. has produced for the U.S. Coast Guard. The company is also building 180 high-speed interdiction boats for the Coast Guard over the next decade, said Bob Herre, president of the Manitowoc Marine Group. The first six of the 45-ft. response boats are expected to be delivered late this year and in early 2008. Defense contacts make up about half of the work done by The Manitowoc Co.'s marine group, said Steve Khail, director of investor relations and corporate communications for The Manitowoc Co. Inc. Manitowoc owns both Marinette Marine Corp. in Marinette and Bay Shipbuilding in Sturgeon Bay. Bay Shipbuilding focuses on much of the commercial work done by the company. In recent years Marinette Marine Corp.