Editing Iowa-class battleship (section)

===Design history===
In March 1938, the General Board followed the recommendations of the Battleship Design Advisory Board, which was composed of the naval architect [[William Francis Gibbs]], [[William Hovgaard]] (then president of [[New York Shipbuilding]]), John Metten, Joseph W. Powell, and the long-retired [[Admiral (United States)|Admiral]] and former Chief of the [[Bureau of Ordnance]] [[Joseph Strauss (admiral)|Joseph Strauss]]. The board requested an entirely new design study, again focusing on increasing the size of the {{cvt|35000|LT|adj=on}} ''South Dakota'' class. The first plans made for this indicated that {{convert|30|kn}} was possible on a standard displacement of about {{convert|37600|LT}}. {{convert|33|kn}} could be bought with {{cvt|220000|shp}} and a standard displacement of around {{convert|39230|LT}}, which was well below the London Treaty's "escalator clause" maximum limit of {{convert|45000|LT|-2}}.{{sfn|Friedman|1986|pp=271, 307}}

These designs were able to convince the General Board that a reasonably well-designed and balanced 33-knot "fast" battleship was possible within the terms of the "escalator clause". However, further studies revealed major problems with the estimates. The speed of the ships meant that more [[Freeboard (nautical)|freeboard]] would be needed both fore and amidships, the latter requiring an additional foot of armored freeboard. Along with this came the associated weight in supporting these new strains: the structure of the ship had to be reinforced and the power plant enlarged to avoid a drop in speed. In all, about {{convert|2400|LT|-1}} had to be added, and the large margin the navy designers had previously thought they had – roughly {{convert|5000|LT|-1}} – was suddenly vanishing.{{sfn|Friedman|1986|pp=309–310}} The draft of the ships was also allowed to increase, which enabled the [[Beam (nautical)|beam]] to narrow and thus reduced the required power (since a lower beam-to-draft ratio reduces [[wave-making resistance]]). This also allowed the ships to be shortened, which reduced weight.{{sfn|Friedman|1986|pp=310–311}}

With the additional displacement, the General Board was incredulous that a tonnage increase of {{convert|10000|LT|-2}} would allow only the addition of {{convert|6|kn}} over the ''South Dakota''s. Rather than retaining the 16-inch/45 caliber Mark 6 guns used in the ''South Dakota''s, they ordered that the preliminary design would have to include the more powerful but significantly heavier [[16"/50 caliber Mark 2 gun|16-inch/50 caliber Mark 2 guns]] left over from the canceled {{sclass|Lexington|battlecruiser|1}}s and {{sclass|South Dakota|battleship (1920)|0}} battleships of the early 1920s.{{sfn|Friedman|1986|pp=310–311}}

The 16"/50 turret weighed some {{convert|400|LT|0}} more than the 16"/45 turret already in use and also had a larger [[barbette]] diameter of {{convert|39|ft|4|in|2}} compared to the latter's barbette diameter of {{convert|37|ft|3|in|2}}, so the total weight gain was about {{convert|2000|LT|-1}}. This put the ship at a total of {{convert|46551|LT}} – well over the {{convert|45000|LT|adj=on}} limit. An apparent savior appeared in a Bureau of Ordnance preliminary design for a turret that could carry the 50-caliber guns and also fit in the smaller barbette of the 45-caliber gun turret. Other weight savings were achieved by thinning some armor elements and substituting construction steel with armor-grade [[Special Treatment Steel]] (STS) in certain areas. The net savings reduced the preliminary design displacement to {{convert|44560|LT}} standard, though the margin remained tight. This breakthrough was shown to the General Board as part of a series of designs on 2 June 1938.{{sfn|Friedman|1986|p=311}}

However, the Bureau of Ordnance continued working on the turret with the larger barbette, while the Bureau of Construction and Repair used the smaller barbettes in the contract design of the new battleships. As the bureaus were independent of one another, they did not realize that the two plans could not go together until November 1938, when the contract design was in the final stages of refinement. By this time, the ships could not use the larger barbette, as it would require extensive alterations to the design and would result in substantial weight penalties. Reverting to the 45-caliber gun was also deemed unacceptable. The General Board was astounded; one member asked the head of the Bureau of Ordnance if it had occurred to him that Construction and Repair would have wanted to know what turret his subordinates were working on "as a matter of common sense". A complete scrapping of plans was avoided only when designers within the Bureau of Ordnance were able to design a new 50-caliber gun, the [[16"/50 caliber Mark 7 gun|Mark 7]], that was both lighter and smaller in outside diameter; this allowed it to be placed in a turret that would fit in the smaller barbette. The redesigned 3-gun turret, equipped as it was with the Mark 7 naval gun, provided an overall weight saving of nearly {{convert|850|LT|0}} to the overall design of the ''Iowa'' class. The contract design displacement subsequently stood at {{convert|45155|LT}} standard and {{convert|56088|LT}} full load.{{sfnm |1a1=Sumrall|1y=1988|1p=35 |2a1=Lyon|2a2=Moore|2y=1978|2p=240}}

In May 1938, the United States Congress passed the [[Second Vinson Act]], which "mandated a 20% increase in strength of the [[United States Navy]]".{{sfn|Rogers|n.d.}} The act was sponsored by [[Carl Vinson]], a [[Democratic Party (United States)|Democratic]] [[United States Congress|Congressman]] from [[Georgia (U.S. state)|Georgia]] who was Chairman of the House Naval Affairs and Armed Services Committee.<ref name="Vinson">Vinson: Congressional biography</ref> The Second Vinson Act updated the provisions of the [[Vinson-Trammell Act]] of 1934 and the Naval Act of 1936, which had "authorized the construction of the first American battleships in 17 years", based on the provisions of the [[London Naval Treaty]] of 1930;{{sfn|Rogers|n.d.}} this act was quickly signed by President [[Franklin D. Roosevelt]] and provided the funding to build the ''Iowa'' class. Each ship cost approximately US$100&nbsp;million.{{sfn|Newhart|2007|p=92}}

As 1938 drew to a close, the contract design of the ''Iowa''s was nearly complete, but it would continuously evolve as the [[New York Navy Yard]], the lead shipyard, conducted the final detail design. These revisions included changing the design of the foremast, replacing the original [[1.1"/75 caliber gun|{{convert|1.1|in|1|adj=on}}/75-caliber gun]]s that were to be used for [[anti-aircraft]] (AA) work with [[Oerlikon 20 mm cannon|{{cvt|20|mm|2}}/70&nbsp;caliber Oerlikon cannons]] and [[Bofors 40 mm Automatic Gun L/60|{{cvt|40|mm|2}}/56&nbsp;caliber Bofors guns]], and moving the [[combat information center]] into the armored hull.<ref>Stillwell, p. 16.{{Incomplete short citation|date=November 2020}}<!--Ambiguous, there are two Stillwells (1986, 1996) cited in article--></ref> Additionally, in November 1939, the New York Navy Yard greatly modified the internal subdivision of the machinery rooms, as tests had shown the underwater protection in these rooms to be inadequate. The longitudinal subdivision of these rooms was doubled, and the result of this was clearly beneficial: "The prospective effect of flooding was roughly halved and the number of uptakes and hence of openings in the third deck greatly reduced." Although the changes meant extra weight and increasing the beam by {{convert|1|ft}} to {{convert|108|ft|2|in}}, this was no longer a major issue; [[United Kingdom|Britain]] and [[France]] had renounced the Second London Naval Treaty soon after the beginning of the [[Second World War]].{{sfn|Friedman|1986|pp=313–314}} The design displacement was {{convert|45873|LT}} standard, approximately 2% overweight, when ''Iowa'' and ''New Jersey'' were laid down in June and September 1940. By the time the ''Iowa''s were completed and commissioned in 1943–44, the considerable increase in anti-aircraft armament&nbsp;– along with their associated splinter protection and crew accommodations&nbsp;– and additional electronics had increased standard displacement to some {{convert|47825|LT}}, while full load displacement became {{convert|57540|LT}}.{{sfn|Friedman|1986|p=449}}{{sfn|Sumrall|1988|p=38}}{{sfn|Garzke|Dulin|1995|pp=147–149}}

{{Quote box|quote=For half a century prior to laying [the ''Iowa'' class] down, the US Navy had consistently advocated armor and firepower at the expense of speed. Even in adopting fast battleships of the ''North Carolina'' class, it had preferred the slower of two alternative designs. Great and expensive improvements in machinery design had been used to minimize the increased power on the designs rather than make extraordinary powerful machinery (hence much higher speed) practical. Yet the four largest battleships the US Navy produced were not much more than 33-knot versions of the 27-knot, 35,000&nbsp;tonners that had preceded them. The ''Iowa''s showed no advance at all in protection over the ''South Dakota''s. The principal armament improvement was a more powerful 16-inch gun, 5&nbsp;calibers longer. Ten thousand tons was a very great deal to pay for 6&nbsp;knots.|author=[[Norman Friedman]]|source=''U.S. Battleships: An Illustrated Design History'', p. 307.|width=67%|align=center}}