USS SC-4, during her service life known as Submarine Chaser No. 4 or S.C. 4, was an SC-1-class submarine chaser built for the United States Navy during World War I.

USS S.C. 4 (left) and her sister ship USS S.C. 1 (right) at Charleston, South Carolina.
History
United States
Name	USS Submarine Chaser No. 4 Retrospectively USS SC-4 (since July 1920)
Builder	Naval Station New Orleans, New Orleans, Louisiana
Commissioned	19 February 1918
Fate	Sold 19 March 1920
General characteristics
Class and type	SC-1-class submarine chaser
Displacement	77 tons normal 85 tons full load
Length	110 ft (34 m) overall 105 ft (32 m) between perpendiculars
Beam	14 ft 9 in (4.50 m)
Draft	5 ft 7 in (1.70 m) normal 6 ft 6 in (1.98 m) full load
Propulsion	Three 220 bhp (160 kW) Standard Motor Construction Company six-cylinder gasoline engines, three shafts, 2,400 US gallons (9,100 L) of gasoline; one Standard Motor Construction Company two-cylinder gasoline-powered auxiliary engine
Speed	18 knots (33 km/h)
Range	1,000 nautical miles (1,900 km) at 10 knots (19 km/h)
Complement	27 (2 officers, 25 enlisted men)
Sensors and processing systems	One Submarine Signal Company S.C. C Tube, M.B. Tube, or K Tube hydrophone
Armament	1 × 3-inch (76.2 mm)/23-caliber gun mount 2 × Colt .30 caliber (7.62 mm) machine guns 1 × Y-gun depth charge projector

SC-4 was a wooden-hulled 110-foot (34 m) submarine chaser built at Naval Station New Orleans in New Orleans, Louisiana. She was commissioned on 19 February 1918 as USS Submarine Chaser No. 4, abbreviated at the time as USS S.C. 4.

During World War I, S.C. 4 served in the Special Hunting Squadron, USS Salem Group, on antisubmarine patrol duty against German submarines in the Gulf of Mexico, and was based at Key West, Florida.

On 19 March 1920, the Navy sold S.C. 4 to David A. Clarkson of Nassau in the Bahamas.

The U.S. Navy adopted its modern hull number system on 17 July 1920. Although Submarine Chaser No. 4 had already been sold by then, since that date she has been referred to retrospectively as USS SC-4 - the shortened name she would have received under the new system had she still been in Navy service at that time.