USS Plymouth (PG-57), a patrol gunboat, was the fourth ship of the United States Navy to be named for Plymouth, Massachusetts, a town founded by the Pilgrims in 1620 on Plymouth Bay, about 35 miles southeast of Boston. Construction Plymouths keel was laid down in 1931, by the Friedrich Krupp Germaniawerft in Kiel, Germany, as Alva. She was originally built as a yacht for William Kissam Vanderbilt II and was named Alva, after his mother, Alva Vanderbilt Belmont. She was given to the United States Navy on 4 November 1941, by her owner and was placed in reduced commission at Jacksonville, Florida, on 29 December 1941. Service history Inshore Patrol Squadron, 1942–1943 She departed Jacksonville on 31 December for the Navy Yard, Washington, DC, arriving there on 4 January 1942. She sailed on 21 January and the next day entered the Norfolk Navy Yard. On 23 January, she was placed in commission in ordinary for conversion to a patrol gunboat. She was placed in full commission 20 April and assigned to Inshore Patrol Squadron, 5th Naval District, based at Norfolk, Virginia. On 8 May she departed Norfolk, forming part of the escort for a convoy en route to Key West, Florida. She was on continuous escort duty between New York, Norfolk, and Key West until 27 August 1942, when she steamed from New York as convoy escort for Guantanamo Bay, Cuba, returning as escort for another convoy 12 September. She made two more convoy escort voyages to Guantanamo Bay and back to New York between 17 September and 24 October 1942. She then resumed escort duty between New York and Key West. During one period of this duty, 24 December 1942 to 13 June 1943, Plymouth completed eight convoy escort voyages from New York to Key West and back. On 2 March 1943, Plymouth collided with the submarine chaser USS SC-1024 off of Cape Hatteras, which resulted in the sinking of the submarine chaser. Sinking, 5 August 1943 On her last voyage, Plymouth departed New Jersey on 4 August 1943 as part of the escort for a convoy bound for Key West. At 21.37 hours the following evening she made underwater sound contact about 90 miles east of Elizabeth City, North Carolina. As she swung left, to bear on the target, a violent underwater explosion occurred just abaft the bridge. The force of the explosion rolled Plymouth to starboard. She