Editing Iowa-class battleship (section)

===Early studies===
Work on what would eventually become the ''Iowa''-class battleship began on the first studies in early 1938, at the direction of Admiral [[Thomas C. Hart]], head of the [[General Board of the United States Navy|General Board]], following the planned invocation of the "escalator clause" that would permit maximum standard capital ship displacement of {{convert|45000|LT|-2}}. Using the additional {{convert|10000|LT|-2}} over previous designs, the studies included schemes for {{convert|27|knot|adj=on}} "slow" battleships that increased armament and protection as well as "fast" battleships capable of {{convert|33|knot}} or more. One of the "slow" designs was an expanded ''South Dakota'' class carrying either twelve [[16"/45 caliber Mark 6 gun|16-inch/45]] [[Caliber (artillery)|caliber]] Mark 6 guns or nine [[18"/48 caliber Mark 1 gun|{{convert|18|in|0|adj=on}}/48]] guns and with more armor and a power plant large enough to drive the larger ship through the water at the same 27-knot maximum speed as the ''South Dakota''s.{{refn|Also considered was the 16-inch/56 caliber gun, but this was dropped in March 1938 due to the weapon's weight.{{sfn|Garzke|Dulin|1995|pp=107–110}}|group=N}} While the "fast" studies would result in the ''Iowa'' class, the "slow" design studies would eventually settle on twelve 16-inch guns and evolve into the design for the {{convert|60500|LT|adj=on}} {{sclass|Montana|battleship|4}} after all treaty restrictions were removed following the start of World War II.{{sfn|Friedman|1986|pp=309, 311}} Priority was given to the "fast" design in order to counter and defeat Japan's {{convert|30|knot|adj=on}}{{sfn|Burr|2010|p=5}} ''Kongō''-class fast battleships, whose higher speed advantage over existing U.S. battleships might let them "penetrate U.S. cruisers, thereby making it 'open season' on U.S. supply ships",<ref>{{cite web |url=https://www.warhistoryonline.com/instant-articles/built-to-last-iowa-class.html |title=Built To Last: Five Decades for the Iowa Class Battleship |author=Winston, George |date=15 September 2018 |website=War History Online |publisher=Timera Inc |access-date=12 January 2019 }}</ref> and then overwhelm the Japanese battle line was therefore a major driving force in setting the design criteria for the new ships, as was the restricting width of the Panama Canal.{{sfn|Burr|2010|p=5}}

For "fast" battleships, one such design, pursued by the Design Division section of the [[Bureau of Construction and Repair]], was a "cruiser-killer". Beginning on 17 January 1938, under [[Captain (United States O-6)|Captain]] [[A.J. Chantry]], the group drew up plans for ships with twelve 16-inch and twenty {{convert|5|in|0|adj=on}} guns, [[Panamax]] capability but otherwise unlimited displacement, a top speed of {{convert|35|kn}} and a range of {{convert|20000|nmi}} when traveling at the more economical speed of {{convert|15|kn}}. Their plan fulfilled these requirements with a ship of {{convert|50940|LT|t}} standard displacement, but Chantry believed that more could be done if the ship were to be this large; with a displacement greater than that of most battleships, its armor would have protected it only against the {{convert|8|in|adj=on}} weapons carried by [[heavy cruiser]]s.{{sfn|Friedman|1986|p=309}}

Three improved plans – "A", "B", and "C" – were designed at the end of January. An increase in [[draft (hull)|draft]], vast additions to the armor,{{refn|The [[belt armor]] was increased from {{convert|8.1|in|0}} to {{convert|12.6|in}}; the [[Deck (ship)|deck armor]] from {{convert|2.3|in}} to {{convert|5|in|0}}; the splinter armor to {{convert|3.9|in}}; the [[Gun turret|turret armor]] from {{convert|9|in|0}} on the front, {{convert|6|in|0}} on the side, and 5 inches on the rear to {{convert|18|in|0}}, {{convert|10|in|0}} and {{convert|8|in|0}}, respectively.{{sfn|Friedman|1986|p=310}}|group=N}} and the substitution of twelve {{convert|6|in|0|adj=on}} guns in the secondary battery were common among the three designs. "A" was the largest, at {{convert|59060|LT}} standard, and was the only one to still carry the twelve 16-inch guns in four triple turrets (3-gun turrets according to US Navy). It required {{cvt|277000|shp|lk=on}} to make {{convert|32.5|knot}}. "B" was the smallest at {{convert|52707|LT}} standard; like "A" it had a top speed of 32.5&nbsp;knots, but "B" only required {{cvt|225000|shp}} to make this speed. It also carried only nine 16-inch guns, in three triple turrets. "C" was similar but added {{cvt|75000|shp}} (for a total of {{cvt|300000|shp}}) to meet the original requirement of {{convert|35|knot}}. The weight required for this and a longer belt – {{convert|512|ft}}, compared with {{convert|496|ft}} for "B" – meant that the ship was {{convert|55771|LT}} standard.{{sfn|Friedman|1986|p=310}}