page_title: North Carolina-class battleship
section_title: Post-war alterations and proposals
hierarchical_section_title: North Carolina-class battleship / Post-war alterations and proposals
caption_attribution_description: USS Washington (BB-56) running post-overhaul trials in Puget Sound, Washington, on 10 September 1945.
context_page_description: The North Carolina class was a class of two fast battleships, North Carolina and Washington, built for the United States Navy in the late 1930s and early 1940s. The Navy was originally uncertain whether the ships should be fast enough to counter the Japanese Kongō-class battlecruiser, which was believed by the United States to be capable of 26 kn, or should sacrifice speed for additional firepower and armor. The 1936 Second London Naval Treaty's requirement that all capital ships have a standard displacement of under 35,000 LT prevented the desired objectives from being fully realized within its limits, and the navy considered over fifty designs before one was chosen.
  Towards the end of this lengthy design period the General Board of the United States Navy declared its preference for a battleship with a speed of 30 knots, faster than any in US service or under construction, with a main battery of nine 14-inch /50 caliber Mark B guns. The board believed that such ships could fulfill a multitude of roles, as they would have enough protection to be put into a battle line while also having enough speed to escort aircraft carriers or engage in commerce raiding.
context_section_description: North Carolina and Washington remained in active duty in the years immediately after the war, possibly because they were more comfortable and less cramped than the four South Dakotas. The ships received alterations during this period; the Ship Characteristics Board (SCB) directed in June 1946 that four of the quadruple-mounted 40 mm guns be removed, though only two were actually taken off each ship. The 20 mm weapons were also reduced at some point so that both ships were decommissioned with sixteen twin mounts. North Carolina and Washington were decommissioned on 27 June 1947 and subsequently moved to the reserve fleet.
  In May 1954, SCB created a class improvement plan for the North Carolinas which included twenty-four 3-inch/50 guns directed by six Mark 56s. A month later, the SCB chairman voiced his belief that the North Carolinas and South Dakotas would be excellent additions to task forces—if they could be faster. The Bureau of Ships then considered and discarded designs that would move these ships at 31 kn (57 km/h; 36 mph), four knots faster than their current attainable speed. In order for a North Carolina to obtain 31 knots, 240,000 shp (180,000 kW) would be required. This, in turn, would necessitate the installation of an extremely large power plant, one which would not fit into the ship even if the third turret was removed. If the outer external belt armor were removed, 216,000 shp (161,000 kW) would still be required. However, no matter if the belt was taken off or not, all of the hull form aft would have to be greatly modified to accept larger propellers. The last strike against the project was the high estimated cost of $40 million—which did not include the cost of activating battleships that had been out of commission for ten years.
  Later calculations proved that the North Carolinas could be lightened from 44,377 long tons to around 40,541 long tons (41,192 t), at which 210,000 shp would suffice. At the trial displacement figure of 38,400 long tons (39,000 t), even 186,000 shp (139,000 kW) would be enough; the 210,000 figure was derived from a 12.5% overestimation to account for a fouled bottom or bad weather. A similar power plant to the one used in the Iowa class (generating 212,000 shp (158,000 kW)) would be enough, and if the third turret was removed there would be no problems with weight, but there was not enough space within the North Carolinas. When compared, the current power plant measured 176 ft × 70 ft × 24 ft (53.6 m × 21.3 m × 7.3 m), but Iowa's was 256 ft × 72 ft × 26 ft (78.0 m × 21.9 m × 7.9 m). Lastly, there would be an issue with the propellers; the Iowa class' were 19 ft (5.8 m) wide, while the North Carolinas were 17 ft (5.2 m). In the end, no conversions were undertaken.
  Designs for helicopter carriers also contained a plan for a conversion of the North Carolinas. At a cost of $30,790,000, the ships would have been able to embark 28 helicopters, 1,880 troops, 530 long tons (540 t) of cargo and 200,000 US gal (760,000 L) of oil. All of the 16-inch and 5-inch guns would have been removed, though the number one turret would have remained so that weights added on the stern half of the ship could be balanced. In place, the ships would have received sixteen 3-inch guns in twin mounts. Displacement would be lowered slightly to a fully loaded weight of about 41,930 long tons (42,600 t), while speed would not have changed. It was estimated that the ships could serve for about fifteen to twenty years at a cost of about $440,000 a year for maintenance. However, it was found that a purpose-built helicopter carrier would be more economical, so the plans were shelved.
caption: Washington steaming at high speed in Puget Sound during post-overhaul trials, 10 September 1945
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