(SP: l. 53'; b. 12'; dr. 3'; s. 22 k.; cpl. 8; a. 1 1-pdr.)
Elf (S. P. 81), a motorboat free leased to the Navy, was commissioned on 3 May 1917, Lieutenant (junior grade) H. J. Bowes, in command, and assigned to the 4th Naval District where she performed patrol duty until July 1918 when she was transferred to the 7th District. She was decommissioned on 9 January 1919 and returned to her owner.