USS Patrol No. 4 (SP-8), often rendered as USS Patrol #4, was an armed motorboat that served in the United States Navy as a patrol vessel from 1917 to 1919. Patrol No. 4 was built as a private motorboat of the same name in 1915 by Britt Brothers at Lynn, Massachusetts. She was one of five motorboats built to the same design for private owners by Britt Brothers as part of the civilian Preparedness Movement program with an understanding that they would enter U.S. Navy service in time of war, the others being Patrol No. 1, which later became USS Patrol No. 1 (SP-45); Patrol No. 2, which later became USS Patrol No. 2 (SP-409); Patrol No. 3, which never entered U.S. Navy service; and Patrol No. 5, which later became USS Patrol No. 5 (SP-29).