Iowa class battleships

The Iowa class of battleships were the largest and fastest class of American battleships ever completed. Four of the six planned ships were completed, and all four saw some service in the Second World War (although only the Iowa and the New Jersey saw extensive use). The Iowa class ships had a remarkably long lifespan and saw combat in Korea, Vietnam, the Lebanon in the 1980s and against Iraq in the 1990s. When the last member of the class was finally decommissioned it was the last battleship to leave service anywhere in the world.

The basic idea was to produce a version of the previous South Dakota class lengthened to give it higher speed. This would require a big increase in displacement, and until 1938 new battleships were limited to 35,000 tons. However the 1936 London Naval Treaty has an escalator clause that allowed the signatories to built 45,000 ton ships if they believed that other countries were building bigger ships. In 1938 this clause was activated after rumours spread that the Japanese were building 46,000 ton ships (in fact this was a massive underestimate - the Japanese were actually building the first two of the 62,000ton Yamato class battleships).

Bows of USS Iowa seen from the bridge
Bows of USS Iowa
seen from the bridge

Work on the new Iowa class began in 1938. The South Dakota class ships had been 666ft long at the waterline, 108ft 2in wide and were powered by four turbines connected to 8 Babcock & Wilcox boilers, producing 130,000shp for a top speed of 27.5kts. The Iowa class ships were the same width, but at 860ft long they were nearly 200ft longer than the South Dakotas, and this space was used to increase their engine power to 212,000shp for a top speed of 32.5kts. The new ships were designed to be able to protect the US fast carriers against Japanese carrier task forces protected by fast heavy cruisers and Kongo class battlecruisers. The Japanese did use the Kongo class ships to protect their carriers, but the changing nature of naval warfare during the Second World War meant that there were never any direct clashes between the Kongo class ships and the Iowa class ships. 

The Iowa class ships carried the same number and calibre of main guns as the South Dakota class ships - nine 16in guns in three triple turrets - two forward and one aft, but the length of the guns was increased from 45 calibres to 50 calibres. They carried the same secondary battery of twenty 5in/38 guns in ten twin turrets. Their armour layout and thickness was also similar to on the South Dakota class, with a 12.1in thick main belt.

The six planned Iowa class ships were authorised in three batches of two. The first two ships, Iowa and New Jersey were authorised in Fiscal Year 1939, the contract was signed on 1 July 1939, and they were laid down in 27 June and 16 September 1940 respectively.

The next pair, Missouri and Wisconsin was part of the FY41 budget. They were ordered on 12 June 1940 and were laid down on 6 January 1941 and 25 January 1941 respectively.

On 19 July 1940 Congress authorised a large emergency construction programme (the Two-Ocean Navy Bill). Seven battleships were included in this programme, including two extra Iowa class ships and the five Montana class ships. None of these ships were completed, and indeed all of them were cancelled in 1943. The last of the Iowa class ships, USS Kentucky, was about two-thirds complete when she was finally scrapped. She remained on the launching slip until 1950 and was redesigned as a missile launching battleship several times during the 1940s and 1950s. This work was never carried out and she was finally sold for scrap in 1958.

The Iowa was completed as a force flagship with an enlarged conning tower but one less quad Bofors gun mounting. All four of the completed ships were perfectly capable of acting as flagships. As with most battleships of the Second World War the number of anti-aircraft guns was greatly increased during the war.

The four completed ships all saw service in the Pacific during the Second World War, with Iowa and New Jersey seeing the most extensive use while the Missouri was chosen for the signing of the Japanese surrender. They were used during the Korean War, where their big guns proved to be very valuable. The New Jersey was reactivated and saw limited action during the Vietnam War,

Most surprising was their recall to the colours in the 1980s as part of President Reagan's 600 ship fleet. They were modernised and saw action off the coast of the Lebanon during the 1980s and in the First Gulf War in the 1990s.

The last two ships in the class were both laid down on 6 December 1942 but neither were completed. The Illinois was cancelled in August 1945, and her engines used in two Fast Replenishment Ships. The Kentucky remained in the building dock until 1950 when she was launched to clear the dock, and was finally sold for scrap in 1958.

Displacement (standard)

48,110t

Displacement (loaded)

57,540t

Top Speed

32.5kts

Range

15,000nm at 15kts

Armour – belt

12.1in on 0.875in STS

 - lower belt

12.1in-1.6in on 0.875in STS

 - armour deck

6in with 1.5in weather deck and 0.625in splinter deck

 - bulkheads

11.3in

 - barbettes

11.6in-17.3in

 - turrets

19.7in face, 7.25in roof, 9.5in side, 12.0in rear

 - CT

17.5in, 7.25in roof

Length

887ft 3in

Width

108ft 2in

Armaments

Nine 16in/50 guns
Twenty 5in/38 guns in ten turrets
Eighty 40mm guns in quad mounts
Forty nine 20mm guns
3 aircraft

Crew complement

1921

Ships in Class

Fate

USS Iowa BB61

Decommissioned after accident in 1989

USS New Jersey BB62

Decommissioned 1991

USS Missouri BB63

Decommissioned 1992

USS Wisconsin BB64

Decommissioned 1991

USS Illinois BB 65

Cancelled August 1945

USS Kentucky BB 66

Sold for break-up September 1958

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How to cite this article: Rickard, J (19 September 2014), Iowa class battleships , http://www.historyofwar.org/articles/weapons_iowa_class_battleships.html

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