The second USS Saco was a yard tug in the United States Navy during the 1920s.

The steam tug Alexander Brown was built in 1912 for the Aransas Dock and Channel Company, Aransas Pass, Texas, by A.C. Brown and Son, Tottenville, New York.

Purchased for use as a yard tug at the Naval Air Station Key West, she operated there as Alexander Brown until 24 November 1920, when she was renamed Saco and redesignated YT-31.

Saco continued yard tug operations until struck from the Navy list on 22 October 1926.

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.