An early photograph of USS S.C. 20, probably around the time of her commissioning in 1917. She carries her original armament, including a Hotchkiss gun forward and a Davis gun amidships, both of which later would be replaced.
History
United States
Name	USS Submarine Chaser No. 20 (1917-1920) USS SC-20 (1920)
Builder	New York Navy Yard, Brooklyn, New York
Commissioned	18 October 1917
Reclassified	SC-20 on 17 July 1920
Fate	Transferred to United States Department of War 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

USS S.C. 20 at the New York Navy Yard in Brooklyn, New York, on 15 September 1917, about five weeks before her commissioning. At right are the bows of two other SC-1-class submarine chasers, both unidentified.

USS SC-20, until July 1920 known as USS Submarine Chaser No. 20 or USS S.C. 20, was an SC-1-class submarine chaser built for the United States Navy during World War I.

SC-17 was a wooden-hulled 110-foot (34 m) submarine chaser built at the New York Navy Yard at Brooklyn, New York. She was commissioned on 18 October 1917 as USS Submarine Chaser No. 20, abbreviated at the time as USS S.C. 20.

S.C. 20 was assigned to the Third Naval District for patrol duties during World War I.

When the U.S. Navy adopted its modern hull number system on 17 July 1920, Submarine Chaser No. 20 was classified as SC-20 and her name was shortened to USS SC-20.

Sometime in 1920, the Navy transferred SC-20 to the United States Department of War for service with the United States Army.

References

• This article incorporates text from the public domain Dictionary of American Naval Fighting Ships. The entry can be found here.
• NavSource Online: Submarine Chaser Photo Archive: SC-20
• The Subchaser Archives: The History of U.S. Submarine Chasers in the Great War Hull number: SC-20
• Woofenden, Todd A. Hunters of the Steel Sharks: The Submarine Chasers of World War I. Bowdoinham, Maine: Signal Light Books, 2006. ISBN 978-0-9789192-0-7.