Authorities also plan to use all-terrain vehicles Thursday to search the shoreline near Port Fourchon, a major base for the U.S. oil and gas industry. Despite a widening search involving Coast Guard boats and aircraft, no other crew members have been spotted. Interrupted by darkness and bad weather, the effort spread to more than 1,440 square miles by Wednesday afternoon, according to a news release. “We had both air and surface assets out last night — nothing materially has changed," Michelli said around dawn Thursday. The boat, capable of working in up to 195 feet of water, can carry a crew of 12, two “special personnel” and 36 passengers, according to the company website.