USS SC-21

History
United States
Name:	USS Submarine Chaser No. 21 (1917-1920) USS SC-21 (1920-1921)
Builder:	New York Navy Yard, Brooklyn, New York
Commissioned:	20 September[1] or 19 October[2] 1917
Reclassified:	SC-21 on 17 July 1920
Fate:	Sold 24 June 1921
General characteristics
Class & 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 SC-21, until July 1920 known as USS Submarine Chaser No. 21 or USS S.C. 21, was an SC-1-class submarine chaser built for the United States Navy during World War I.

SC-21 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 either 20 September^[3] or 19 October^[4] 1917 as USS Submarine Chaser No. 21, abbreviated at the time as USS S.C. 21, under the command of Lieutenant Alfred Y. Lanphier, who later would become the commander of the USS Patterson Group of submarine chasers.

Assigned to the Second Naval District, S.C. 21 operated with the Experimental Unit at New London, Connecticut. On 6 May 1918, Lieutenant, junior grade, Henry Hartley was relieved of command of Submarine Chaser No. 253 and took command of S.C. 21.

When the U.S. Navy adopted its modern hull number system on 17 July 1920, Submarine Chaser No. 21 was classified as SC-21 and her name was shortened to USS SC-21.

On 24 June 1921, the Navy sold SC-21 to Joseph G. Hitner of Philadelphia, Pennsylvania.

Notes

1. The Subchaser Archives: The History of U.S. Submarine Chasers in the Great War Hull number: SC-21.
2. Dictionary of American Naval Fighting Ships at http://www.history.navy.mil/danfs/sc1/sc-1-sc-100v1.htm and NavSource Online: Submarine Chaser Photo Archive: SC-21.
3. The Subchaser Archives: The History of U.S. Submarine Chasers in the Great War Hull number: SC-21.
4. Dictionary of American Naval Fighting Ships at http://www.history.navy.mil/danfs/sc1/sc-1-sc-100v1.htm and NavSource Online: Submarine Chaser Photo Archive: SC-21.

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-21
• The Subchaser Archives: The History of U.S. Submarine Chasers in the Great War Hull number: SC-21
• 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.