USS Seatag (SP-505)

USS Seatag (SP-505), also spelled Sea Tag, was a United States Navy patrol vessel in commission from 1917 to 1918.

Seatag was built in 1917 as a private motorboat of the same name by the Great Lakes Boatbuilding Corporation at Milwaukee, Wisconsin. On 9 July 1917, the U.S. Navy acquired her under a free lease from her owner, Donald Ryerson of Chicago, Illinois, for use as a section patrol vessel during World War I. She was commissioned as USS Seatag or Sea Tag (SP-505) on 1 August 1917 with Ensign Sylvester Aparling, USNRF, in command.

Seatag served on the Great Lakes for the rest of World War I. She served primarily on the Detroit River and St. Clair River patrols until 4 October 1918.

Seatag was decommissioned on 18 November 1918, a week after the end of World War I. She was returned to Ryerson on 7 March 1919.