page_title: South Dakota-class battleship (1939)
section_title: Main battery
hierarchical_section_title: South Dakota-class battleship (1939) / Specifications / Armament / Main battery
caption_attribution_description: The South Dakota (BB-57) at Scapa Flow in 1943.
context_page_description: The South Dakota class was a group of four fast battleships built by the United States Navy. They were the second class of battleships to be named after the 40th state; the first were designed in the 1920s and canceled under the terms of the Washington Naval Treaty.
  Four ships comprised the class: South Dakota, Indiana, Massachusetts, and Alabama. They were designed to the same treaty standard displacement limit of 35,000 long tons as the preceding North Carolina class and had the same main battery of nine 16"/45 caliber Mark 6 guns in three-gun turrets, but were more compact and better protected. The ships can be visually distinguished from the earlier vessels by their single funnel, compared to twin funnels in the North Carolinas. According to naval historians William Garzke and Robert Dulin, the South Dakota design was the best "treaty battleship" ever built.
  Construction began shortly before World War II, with Fiscal Year 1939 appropriations. Commissioning through the summer of 1942, the four ships served in both the Atlantic, ready to intercept possible German capital ship sorties, and the Pacific, in carrier groups and shore bombardments.
context_section_description: The South Dakota-class battleships carried a main battery of nine 16-in (406 mm)/45 caliber Mark 6 guns in three three-gun turrets, identical to the North Carolina-class. Two of these turrets were placed in a superfiring pair forward; the third turret was mounted aft of the main superstructure. These guns fired a 2,700 lb (1,200 kg) Mark 8 armor-piercing (AP) shell at a rate of two per minute per gun. The guns could either use a full propellant charge of 535 lb (243 kg), a reduced charge of 295 lb (134 kg), or a reduced flashless charge of 315 lb (143 kg). This provided a muzzle velocity of 2,300 feet per second (700 meters per second) for the AP shell with the full propellant charge, while the reduced version provided a correspondingly lower muzzle velocity of 1,800 ft/s (549 m/s). 130 shells were stowed for each gun, which came to a total of 1,170. The guns in all three turrets could elevate to 45 degrees, but only I and III turrets could depress to −2 degrees; the superfiring II turret was not able to depress. This enabled a maximum range of 36,900 yards or 18.2 nmi (20.9 mi; 33.7 km) with the Mark 8 projectile.  The turrets were able to train 150 degrees in both directions from the centerline, which enabled a wide arc of fire. The guns could be elevated or depressed at a rate of 12 degrees per second, and the turrets could train at 4 degrees per second.
caption: South Dakota shows the range of independent elevation of her main guns
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