Gem (S. P. 41)
Former name retained.
Gem, a steam yacht, was built in 1913 by George Lawley & Sons, Neponset, Mass.; chartered 26 March 1917 from William Ziegler, Jr.; and commissioned at New York L June 1917, Ens. Leroy J. Small, USNRF, in command.
Gem performed harbor entrance patrol at New Haven, Conn. until 12 December 1917. She was then assigned to experimental work under the Submarine Defense Association. In this duty, carried out at New York, New London, Newport, and New Haven, she experimented with camouflage defense; tested the Bates Automatic Course Indicator; and experimented with various submarine detection devices, including the Sanborn Speed Indicator. She also performed colloidal fuel (pulverized coal) experiments at New Haven and New York. She decommissioned at New York 10 January 1919 arid was returned to her owner the same day.