U.S. Sailors, assigned to the amphibious dock landing ship USS Tortuga (LSD 46), stand in formation during a hull swap ceremony with the amphibious dock landing ship USS Ashland (LSD 48) at Commander Fleet Activities Sasebo, Japan, Aug. 23, 2013. Hull swaps, or ship rotations, are part of the Navy's long-term plan to routinely replace older ships with newer, more capable ships to improve forward-deployed naval forces operations.