Tillamook was built as a civilian motorboat or motor yacht of the same name in 1911 by the Matthews Boat Company at Port Clinton, Ohio. The U.S. Navy purchased her from her owner, Mr. D. C. Whitney of Detroit, Michigan, on 14 May 1917 for World War I service as a patrol vessel. She was commissioned on 1 June 1917 as USS Tillamook (SP-269), although some sources claim that she was commissioned as USS SP-269 rather than under her civilian name. SP-269 remained active in the 9th Naval District until the autumn of 1919. She was sold to Mr. George Jerome of Detroit on 20 November 1919.