USS Dreadnought (SP-584), later USS SP-584, was a United States Navy patrol vessel in commission from 1917 to 1919. Dreadnought was built as a private fast "runabout" motorboat of the same name by R. Bigelow at Monument Beach, Massachusetts, in either 1916 or 1917. On 17 May 1917, the U.S. Navy acquired her from her owner, Eldon B. Keith of Brockton, Massachusetts, for use as a section patrol boat during World War I. She was commissioned as USS Dreadnought (SP-584) on 20 October 1917. SP-584 was returned to her owner on 6 June 1919.