USS Montana BB-51

USS Montana BB-51 was a South Dakota class battleship laid down in 1920 for the U.S. Navy, but never completed.

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 (36,000 t), construction was halted in early 1922. The unfinished hull was scrapped the following year when Montana was 27.6% complete. The guns were transferred to the U.S. Army and their boilers and armor were used to modernize older battleships.

South Dakota 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)
Planned: 6
Cancelled: 6

General characteristics

Type: Battleship
Displacement:
43,200 long tons (43,900 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)