Starboard Unit was built as a civilian motorboat of the same name. On 5 November 1918, the U.S. Navy acquired her under a free lease from her owner, Joseph W. Marsh, for use as a section patrol boat during World War I.
World War I ended on 11 November 1918, six days after Starboard Units acquisition. No longer needed for naval service, Starboard Unit never received a section patrol (SP) number and was never commissioned. The Navy returned her to Marsh on 5 March 1919.