A former name retained.
(SP-512: dp. 499; l 197'6"; b. 32'6"; d. 17'; s. 10 k.; cpl. 75; a. 43")
Guinevere (SP-512) was built by George Lawley & Sons, Boston, Mass., in 1908 and acquired from her owner, Edgar Palmer of New York, 10 June 1917. She commissioned 20 July 1917, Li. Guy Davis in command.
Sailing from the Newport Coaling Station 1 August 1917, Guinevere reached Brest, France, 29 August, after stops at St. Johns, Newfoundland, and the Azores. From there she patrolled the French coast and escorted convoys to Quiberon, Ushant, Lorient, and St. Nazaire. Guinevere ran aground and was wrecked off the French coast 26 January 1918, with no loss of life; the wreck was purchased by Societe Americaine de Sauvetage 30 June 1919.