Two interesting vessels are currently lying at Faslane. CAROLYN CHOUEST, the larger of the two, is a dedicated submarine support vessel working on lease to the United States Navy's Military Sealift Command. A 72.5 metre long ship, she was built in 1994 by North American Shipbuilding at Larose in Louisiana as an offshore supply vessel for Edison Chouest Offshore. She is now the designated support vessel for the small submarine, simply known as NR-1, seen lying alongside her. This is a nuclear powered research vessel, never named or commissioned, capable of undertaking search and recovery work, oceanographic research and underwater survey and maintenance work. She dates from 1969, and is 45 metres in length. Amongst other missions that NR-1, described as 'the best kept secret of the silent service', has undertaken have been the charting of the wreck of USS MONITOR, the first ironclad vessel of the US Navy which was sunk during the Civil War in 1863.