USS Elf (SP-81)

USS Elf (SP-81) was an armed motorboat that served in the United States Navy as a patrol vessel from 1917 to 1919. Elf was a civilian motorboat completed in early 1917 by Stanley Vansant. In early May 1917, the U.S. Navy acquired her under a free lease from her owner, Louis H. Eisenlohr of Philadelphia, Pennsylvania, for World War I service as a patrol boat. She was commissioned as USS Elf (SP-81) on 3 May 1917 with Lieutenant, junior grade, H. J. Bowes in command.

Elf performed patrol duty in the 4th Naval District until July 1918, when she was transferred to the 7th Naval District.

Elf was decommissioned on 9 January 1919 and returned to her owner on 10 January 1919.