USS Plymouth ( PG - 57 ) 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 . " Plymouth " ' s keel was laid down in 1931 by the Friedrich Krupp Germaniawerft in Kiel , Germany , as " Alva " . She was given to the United States Navy on 4 November 1941 by her owner , W . K . Vanderbilt II of New York City , and was placed in reduced commission at Jacksonville , Florida , on 29 December 1941 with Commander F . W . Schmidt in command . 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 . Sinking , 5 August 1943 . On her last voyage , " Plymouth " departed New York City 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 then took on a heavy list to port with her entire port side forward of amidships in flames . She sank within two minutes . Lieutenant Ormsby M . Mitchel , Jr . , USNR , in command of " Plymouth " , was thrown violently against a bulkhead and sustained serious injuries , which later required amputation of his left leg . Despite his own condition , he directed abandon ship operations , remaining at his post until the ship went down . Rescued from a raft by , Lieutenant Mitchel was awarded the Navy Cross for extraordinary heroism . Soundman 3 / Class Franklin A . McGinty was also awarded the Navy Cross and Purple Heart posthumously . Ensign Rubin Keltch , of New York City , was also awarded the Navy Cross posthumously for his service aboard the U . S . S . Plymouth . Ensign Keltch unhesitatingly risked his life to assist several survivors to safety . After making sure they were safe he went back in to the engine room to save several men , but although the men came out he never did Rescue operations were hampered by heavy seas and sharks . Only 85 of the crew survived to be taken to Norfolk on 6 August . A Board of Investigation concluded that " Plymouth " had been sunk by a torpedo fired from an enemy submarine . The submarine was .