9 (SP-679), was a United States Navy armed tug and minesweeper in commission from 1917 to 1919.

9 was built as a commercial tug of the same name by William R. Trigg at Richmond, Virginia, in 1904.

In September 1917, the U.S. Navy acquired her from her owner, the Pennsylvania Railroad, for use during World War I.

9 took up tug and minesweeping duties in New York Harbor for the rest of World War I and for several weeks after its conclusion.

9 was returned to the Pennsylvania Railroad on 2 January 1919, having remained active in naval service until that day.