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USS Missouri (BB-63)

Iowa-class battleship of the U.S. Navy

  • 37 min read
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Through World War II and Tide

After World War II, Missouri served in various diplomatic, show of force and training missions. In 1950, the ship ran aground during high tide in the Chesapeake Bay and after great effort was re-floated several weeks later. She later fought in the Korean War during two tours between 1950 and 1953. Missouri was the first American battleship to arrive in Korean waters and served as the flagship for several admirals. The battleship took part in numerous shore bombardment operations and also served in a screening role for aircraft carriers. Missouri was decommissioned in 1955 and transferred to the reserve fleet (also known as the "Mothball Fleet").

Missouri was reactivated and modernized in 1984 as part of the 600-ship Navy plan. Cruise missile and anti-ship missile launchers were added along with updated electronics. The ship served in the Persian Gulf escorting oil tankers during threats from Iran, often while keeping her fire-control systems trained on land-based Iranian missile launchers. She served in Operation Desert Storm in 1991 including providing fire support.

Missouri was again decommissioned in 1992, but remained on the Naval Vessel Register until her name was struck in 1995. In 1998, she was donated to the USS Missouri Memorial Association and became a museum ship at Pearl Harbor, Hawaii, where she still sits to this day.

Background and description

The Iowa class of fast battleships was designed in the late 1930s in response to the US Navy's expectations for a future war with the Empire of Japan. The last battleships to be built by the United States, they were also the US Navy's largest and fastest vessels of the type. American officers preferred comparatively slow but heavily armed and armored battleships, but Navy planners determined that such a fleet would have difficulty in bringing the faster Japanese fleet to battle, particularly the Kongō-class battlecruisers and the aircraft carriers of the 1st Air Fleet. Design studies prepared during the development of the earlier North Carolina and South Dakota classes demonstrated the difficulty in resolving the desires of fleet officers with those of the planning staff within the displacement limits imposed by the Washington Naval Treaty system, which had governed capital ship construction since 1923. An escalator clause in the Second London Naval Treaty of 1936 allowed an increase from 35,000 long tons (36,000 t) to 45,000 long tons (46,000 t) in the event that any member nation refused to sign the treaty, which Japan refused to do.

Missouri is 887 feet 3 inches (270.4 m) long overall and is 860 feet (262.1 m) long at the waterline. The ship has a beam of 108 ft 2 in (33 m) and a draft of 37 ft 9 in (11.5 m) at her full combat load of 57,540 long tons (58,460 t). The Iowa-class ships are powered by four General Electric geared steam turbines, each driving one screw propeller using steam provided by eight oil-fired Babcock & Wilcox boilers. Rated at 212,000 shaft horsepower (158,000 kW), the turbines were designed to give a top speed of 32.5 knots (60.2 km/h; 37.4 mph), but were built to handle a 20 percent overload. None of the Iowas ever ran speed trials in deep water, but the Bureau of Ships estimated that they could reach a speed of about 34 knots (63 km/h; 39 mph) from 225,000 shp (168,000 kW) at a light displacement of 51,209 long tons (52,031 t). The ships had a designed cruising range of 15,000 nautical miles (28,000 km; 17,000 mi) at a speed of 15 knots (28 km/h; 17 mph), although the New Jersey's fuel consumption figures during her sea trials suggest that her range was at least 20,150 nmi (37,320 km; 23,190 mi) at that cruising speed. Their designed crew numbered 117 officers and 1,804 enlisted men which had greatly increased by the end of the war in 1945. Missouri's crew at that time numbered 189 officers and 2,978 sailors.

Armament, fire control, sensors and aircraft

The main battery of the Iowa-class ships consisted of nine 16 in (406 mm)/50 caliber Mark 7 guns in three triple-gun turrets on the centerline, two of which were placed in a superfiring pair forward of the superstructure, with the third aft. Going from bow to stern, the turrets were designated I, II, and III. Their secondary battery consisted of twenty 5 in (127 mm)/38 caliber dual-purpose guns mounted in twin-gun turrets clustered amidships, five turrets on each broadside. Unlike their sister ships Iowa and New Jersey that were the first pair of ships built, Missouri and Wisconsin were completed with an anti-aircraft suite of twenty quadruple mounts for 40 mm (1.6 in) Bofors AA guns, nine mounts on each broadside and one each on the roofs of Turrets II and III. Forty-nine 20-millimeter (0.8 in) Oerlikon light AA auto-cannon in single mounts were distributed almost the length of the ships.

The primary means of controlling the main armament are two Mark 38 directors for the Mark 38 fire-control system mounted at the tops of the fore and aft fire-control towers in the superstructure. These directors were equipped with 25-foot-6-inch-long (7.8 m) rangefinders, although their primary sensor was the Mark 8 fire-control radar mounted on their roofs. A secondary Mark 40 fire-control director was installed inside the armored conning tower at the front of the superstructure that used the Mark 27 fire-control radar positioned on the top of the conning tower. Each turret is fitted with a rangefinder 46 feet (14 m) long and can act as a director for the other turrets. Four Mark 37 gunnery directors, two on the centerline at the ends of the superstructure and one on each broadside, control the five-inch guns. Each director was equipped with a 15-foot (4.6 m) rangefinder and a pair of radars on its roof. These were a Mark 12 fire-control system and a Mark 22 height-finder radar. Each 40 mm mount was remotely controlled by a Mark 51 director that incorporated a Mark 14 lead-computing gyro gunsight while the sailors that used the 20 mm gun used a Mark 14 sight to track their targets.

A SK-2 early-warning radar was fitted on the ship's foremast; above it was a SG surface-search radar. The other SG radar was mounted at the top of the mainmast positioned on the rear funnel.

The Iowas were built with two rotating aircraft catapults on their stern for floatplanes and a large crane was fitted to recover them. Initially a trio of Vought OS2U Kingfishers were carried, but these were replaced by Curtiss SC Seahawks in December 1944.

Protection

The internal waterline armor belt of the Iowa-class ships is 12.1 in (307 mm) thick and has a height of 10 ft 6 in (3.2 m). Below it is a strake of Class B homogeneous armor plate that tapers in thickness from 12.1 inches at the top to 1.62 in (41 mm) at the bottom and is 28 ft (8.5 m) high. The two strakes of armor are inclined outwards at the top 19 degrees to improve the armor's resistance to horizontal fire. In general the vertical armor plates are made from Class A cemented armor and the horizontal armor from Class B or special treatment steel (STS). The belt armor extends to the two transverse bulkheads fore and aft of the main-gun barbettes, forming the armored citadel. Part of the lower armor belt extends aft from the rear bulkhead to protect the ships' steering gear. Its maximum thickness ranges from 13 to 13.5 in (330 to 343 mm) at the top and the plates taper to 5 inches at the bottom. Unlike the Iowa and New Jersey, the armor plates in the forward transverse bulkhead in Missouri and Wisconsin have a maximum thickness of 14.5 in (368 mm) at the top that tapers to 11.7 in (297 mm). The aft bulkhead is a consistent 14.5 inches in thickness, but does not go below the lower belt extension due it meeting the armored third deck protecting the shafts and steering gears; the steering gear is closed by another 14.5-inch aft bulkhead.

The main-gun turrets have Class B plates 19.5 in (495 mm) thick on their faces and 9.5 in (241 mm) of Class A plates on their sides. The armor plates protecting their barbettes range in thickness from 17.3 in (439 mm) to 14.8 in (376 mm) and 11.6 in (295 mm) with the thickest plates on the sides and the thinnest ones on the front and back. The sides of the conning tower are 17.3 in (440 mm) thick. The main deck of the Iowas consists of 1.5 in (38 mm) of STS. Below this deck, the roof of the armored citadel is formed by 6 in (152 mm) of armor in two layers. Below this is a deck of 0.625-inch (16 mm) STS plates intended to stop splinters from shells that pierced the armored deck above it. The armor deck extends aft and the roof of the steering gear compartment is 6.2 in (160 mm) thick.

The underwater protection system of the Iowa-class battleships consists of three watertight compartments outboard of the lower armor belt and another behind it. The two outermost compartment are kept loaded with fuel oil or seawater to absorb the energy of the torpedo warhead's detonation and slow the resulting splinters so they can be stopped by the lower armor belt. Behind the belt is a holding bulkhead intended to protect the ships' inner spaces from any splinters that might penetrate and the subsequent flooding. For protection against naval mines, the Iowas have a double bottom that runs the full length of the ships and increases to a triple bottom except at the bow and stern.

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