SAN FRANCISCO - Crewmen aboard a 25-foot response boat, from Coast Guard Station San Francisco, stand watch while maintaining a safety zone for a barge carrying three 253-foot-tall cranes March 16, 2010. Two response boats from the station ensured mariners didn't present a hazard to navigation for the barge that narrowly passed under the Golden Gate and Bay Bridges. U.S. Coast Guard photo by Petty Officer 3rd Class Erik Swanson