South Dakota-class battleship (1920)

Artist's concept of the South Dakota class
Class overview
Name	South Dakota class
Operators	United States Navy
Preceded by	Colorado class
Succeeded by	North Carolina class
Cost	$21,000,000 (cost limit)
Built	1920–1923
Planned	6
Cancelled	6
General characteristics
Type	Battleship
Displacement	43,200 long tons (43,893 t) (normal) 47,000 long tons (47,800 t) (full load)
Length	684 ft (208.5 m) (o/a) 660 ft (201.2 m) (waterline)
Beam	106 ft (32.3 m)
Draft	33 ft (10.1 m)
Installed power	12 × water-tube boilers 60,000 shp (45,000 kW)
Propulsion	4 × propeller shafts; 4 × turbo-electric generators
Speed	23 knots (43 km/h; 26 mph)
Range	8,000 nmi (15,000 km; 9,200 mi) at 10 knots (19 km/h; 12 mph)
Complement	137 officers, 1404 enlisted men, 75 marines
Armament	4 × triple 16 in (406 mm) guns 16 × single 6 in (152 mm) guns 4 × 3 in (76 mm) DP guns 2 × 21 in (533 mm) torpedo tubes
Armor	Belt: 8–13.5 in (203–343 mm) Barbettes: 4.5–13.5 in (114–343 mm) Turrets: 5–18 in (127–457 mm) Conning tower: 8–16 in (203–406 mm) Decks: 3.5–6 in (89–152 mm) Bulkheads: 8–13.5 in (203–343 mm) Uptakes: 9–13.5 in (229–343 mm)

The first South Dakota class was a group of six battleships that were laid down in 1920 for the U.S. Navy, but were never completed; designed to achieve 23 knots (43 km/h; 26 mph), they represented an attempt to catch up with the increasing fleet speeds of its main rivals, the British Royal Navy and Imperial Japanese Navy.

The South Dakotas were authorized in 1917, but work was postponed so that the U.S. Navy could incorporate information gained from the Battle of Jutland, fought in mid-1916, in their design. Work was further postponed to give destroyers and other small fighting vessels priority as they were needed urgently to fight German U-boats in the North Atlantic. Construction started only in 1920. As the Washington Naval Treaty of 1922 both restricted the total battleship tonnage allowed the U.S. Navy, and limited individual ship size to 35,000 long tons (35,562 t), construction was halted in early 1922. The unfinished hulls were scrapped the following year, the guns were transferred to the U.S. Army and their boilers and armor were used to modernize older battleships.