(SP-471: t. 17; l. 48'6"; b. 11'6"; dr. 3'1"; s. 6.9 k.; cpl. 8; a. 1 1-pdr., 1 mg.)
The second Sylvia (SP-471)-a motor boat built by Sam Williams at Marco, Fla.-was acquired by the Navy on 6 June 1917 from J. Alwood of Winter Haven, Fla., and commissioned on 4 September 1917.
Sylvia was assigned to scout patrol duty in the 7th Naval District. On 11 April 1918, Sylvia's name was cancelled to end confusion associated with the converted steam yacht, the first Sylvia. She was subsequently known by her number, SP-471. She was anchored in North Beach Basin, Key West, Fla., on 9 September 1919, when a hurricane struck the area. SP-471 was beaten to pieces against the wall of the basin and completely wrecked. She was ordered struck from the Navy list on 4 October 1919.