Editing Montana-class battleship (section)

==Specifications==
[[File:USS Montana bb67.jpg|thumb|An artist's impression of the ''Montana'' class]]

=== General characteristics ===
As authorized, the ''Montana''-class ships (design "BB 67-4") would have been {{cvt|890|ft}} [[long at the waterline]] and {{cvt|921|ft|3|in}} [[long overall]]. At the waterline, their [[beam (nautical)|beam]] was to have been {{cvt|115|ft}}, but their maximum beam increased to {{cvt|121|ft|2|in}}. The ships were to have had a [[standard displacement]] of {{cvt|60500|LT}}, with a designed trials displacement of {{cvt|68317|LT}}. [[Full load]] displacement increased to {{cvt|70965|LT}}, and emergency load grew further to {{cvt|71922|LT}}. At their standard displacement, the ships would have had a [[draft (hull)|draft]] of {{cvt|35|ft}}, while at emergency load, the draft increased to {{cvt|36|ft|10|in}}. The ships would have had a [[metacentric height]] of {{convert|8.2|ft}}. Their projected crew was to have amounted to 115&nbsp;officers and 2,240&nbsp;enlisted men; this grew to 189&nbsp;officers and 2,789&nbsp;enlisted men while serving as a [[flagship]].{{sfn|Friedman|1985|p=450}}{{sfn|Garzke|Dulin|1995|pp=171–175}}

The ''Montana'' design shares many characteristics with the previous classes of American fast battleships starting from the ''North Carolina'' class, such as a [[bulbous bow]], a [[Double hull|triple bottom]] under the [[armored citadel]], and twin skegs in which the inner shafts were housed. The ''Montana''s{{'}} overall construction would have made extensive use of welding for joining structural plates and homogeneous armor, which saved weight compared to traditional [[rivet]]ing. Like all of the US interwar designs, the ''Montana''s would have had a [[flush deck|flush]] [[main deck]] that was steeply flared at the bow to reduce the amount of water taken on in heavy seas. The ''Montana'' class would have carried three aircraft for [[Aerial reconnaissance|reconnaissance]] and gunnery spotting. They would have been operated from catapults on the ship's fantail, as was standard for US battleship designs of the period.{{sfn|Garzke|Dulin|1995|pp=171–175}}{{sfn|Friedman|1980|pp=97–100}}

===Propulsion===
[[File:Montana-Klasse Modell.jpg|thumb|left|Model of the ''Montana'' class]]

The propulsion plant of the ''Montana''s would have consisted of eight oil-fired [[Babcock & Wilcox]] two-drum boilers with a steam pressure of {{cvt|565|psi}} and a steam temperature of {{cvt|850|F}}. The boilers supplied steam to four geared [[steam turbine]]s, each driving one [[screw propeller]].{{sfn|Garzke|Dulin|1995|pp=174–175}} The boilers were vented through a pair of [[funnel (ship)|funnels]] placed on the centerline [[amidships]].{{sfn|Friedman|1980|p=100}} To meet the high electrical loads anticipated for the ships, the design was to have ten 1,250&nbsp;kW ship service turbogenerators (SSTG), providing a total of 12,500&nbsp;kW of non-emergency electrical power at 450 volts [[alternating current]]. The ships were also to be equipped with two 500&nbsp;kW emergency diesel generators.{{sfn|Garzke|Dulin|1995|p=170}}

The turbines were rated to produce {{cvt|43000|hp|MW}} each, for a total propulsive power of {{cvt|172000|hp|MW}}. The propulsion system was intended to produce a design speed of 28 knots at 70,500 tons displacement.{{sfn|Garzke|Dulin|1995|pp=174–175}} The ''Montana''s were designed to carry {{cvt|7500|LT}} of [[fuel oil]] and had a nominal range of {{cvt|15000|nmi|-2}} at {{cvt|15|knot}}. Two semi-balanced rudders were placed behind the two inboard screws. The inboard shafts were housed in skegs, which, while increasing hydrodynamic drag, substantially strengthened the stern structure.{{sfn|Garzke|Dulin|1995|p=171}}

While less powerful than the {{cvt|212000|hp}} powerplant used by the ''Iowa''s, the ''Montana''{{'}}s plant enabled the machinery spaces to be considerably more subdivided, with extensive longitudinal and traverse subdivisions of the boiler and engine rooms. The machinery arrangement was reminiscent of that of the {{sclass|Lexington|aircraft carrier|4}}, with the boiler rooms flanking the two central turbine rooms for the inboard shafts, while the turbine rooms for the wing shafts were placed at the after end of the machinery spaces.{{sfn|Friedman|1985|p=339}} ''Montana''{{'}}s machinery arrangement combined with increased power would eventually be used on the ''Midway'' class.{{sfn|Friedman|1983|p=219}}

=== Armament ===
[[File:Iowa 16 inch Gun-EN.svg|thumb|right|Cutaway of a 16-inch gun turret]]

The primary armament of a ''Montana''-class battleship would have been twelve [[16"/50 caliber Mark 7 gun|{{convert|16|in|mm|0|adj=on}}/50 caliber Mark 7 guns]], which were to be mounted in four three-gun turrets. The turrets were placed in two [[superfire|superfiring]] pairs, one forward and one aft.{{sfn|Friedman|1980|p=100}} The guns fired two types of shells: a {{cvt|2700|lb|kg}} armor-piercing shells and {{cvt|1900|lb|kg}} high capacity (HC) shells that carried a larger [[Shell (projectile)#High-explosive shells|high-explosive]] bursting charge. The shells had [[muzzle velocity|muzzle velocities]] of {{cvt|2500|ft/s}} and {{cvt|2690|ft/s}}, respectively. Firing AP shells at the maximum elevation of 45&nbsp;degrees, the guns could reach targets out to {{cvt|42345|yd}}, while the lighter HC shells had a slightly reduced range of {{cvt|41604|yd}}. The shells had a flight time in excess of eighty seconds at those distances. At a realistic engagement distance of {{cvt|20000|yd}}, the AP shells could penetrate {{cvt|20|in|0}} of steel armor. The guns had a [[rate of fire]] of two shots per minute, and had a rate of train of four degrees per second. They had to be returned to 5&nbsp;degrees elevation for reloading.{{sfn|Campbell|1985|pp=117–118}}{{sfn|Garzke|Dulin|1995|pp=310–311, 326–327}}

The secondary armament for the ''Montana''-class ships was to be twenty {{cvt|5|in|0}}/54 cal  Mark 16 [[dual-purpose gun]]s housed in ten two-gun turrets along the superstructure.{{sfn|Friedman|1980|p=100}} These guns, designed for the ''Montana'' class, were intended to improve the effective range over the shorter-barreled Mark 12 guns then in service. They fired a {{cvt|70|lb}} projectile at a muzzle velocity of {{cvt|2650|ft/s}} and had a maximum range of {{cvt|25909|yd}} against surface targets and a maximum ceiling of {{cvt|51600|ft}} against aerial targets. The guns had a rate of fire of fifteen shots per minute.{{sfn|Campbell|1985|p=143}}

Each ship would have carried a light anti-aircraft armament of thirty-two [[Bofors 40 mm Automatic Gun L/60|{{cvt|40|mm}} Bofors guns]] and twenty [[Oerlikon 20 mm cannon|{{cvt|20|mm}} Oerlikon guns]]. The Bofors guns were to be carried in eight quadruple mounts, while the Oerlikons were to have been mounted individually, although the number of Bofors and Oerlikon mounts would likely have increased considerably had the ships been built.{{sfn|Friedman|1980|p=100}} The Bofors guns fired {{cvt|1.98|lb}} shells at a velocity of {{cvt|2890|ft/s}}, and they had a maximum ceiling of {{cvt|22800|ft}}. The Oerlikon guns were supplied with {{cvt|.27|lb}} shells, which they fired with a muzzle velocity of {{cvt|2740|to|2770|ft/s}}.{{sfn|Campbell|1985|p=147}}

=== Armor ===
[[File:USS Montana (BB-67) Stern.jpg|thumb|right|Stern view of a ''Montana''-class battleship model]]

As designed, the ''Montana''s used the [[All or nothing (armour)|"all or nothing"]] armor philosophy, with most of the armor concentrated on the citadel that includes the machinery spaces, armament, magazines, and command and control facilities. The belt armor would be {{cvt|16.1|in|0}} Class A face-hardened [[Krupp armor|Krupp cemented]] (K.C.) armor mounted on {{cvt|1|in}} [[Special Treatment Steel]] (STS), inclined at 19 degrees. Below the waterline, the belt tapered to {{cvt|10.2|in|0}}. To protect against potential underwater shell hits, the ships would have a separate Class B homogeneous Krupp-type armor lower belt, {{cvt|8.5|in|0}} by the magazines and {{cvt|7.2|in|0}} by the machinery, that would also have served as one of the [[torpedo bulkhead]]s, inclined at 10 degrees; this lower belt would taper to 1 inch at the triple bottom and be mounted on {{cvt|0.75|in}} STS. The ends of the armored citadel would be closed by Class A traverse bulkheads {{cvt|18|in|0}} thick in the front and {{cvt|15.25|in}} in the aft.{{sfn|Garzke|Dulin|1995|p=173}}

The deck armor would be in three layers: the first consisting of {{cvt|0.75|in}} STS laminated on {{cvt|1.5|in}} STS for a total of {{cvt|2.25|in}} STS weather deck, the second consisting of {{cvt|5.8|in|0}} Class B laminated on {{cvt|1.25|in|0}} STS for a total of {{cvt|7.05|in|0}}, and a third {{cvt|0.625|in|0}} splinter deck. Over the magazines, the splinter deck would be replaced by a {{cvt|1|in}} STS third deck to protect from spalling. Total armor thickness on the centerline would therefore have been 9.925 in (252&nbsp;mm) over the citadel and 10.3 in (262&nbsp;mm) thick over the magazines. The outboard section would have had {{cvt|6.1|in|0}} Class B laminated on {{cvt|1.25|in|0}} STS for a total of {{cvt|7.35|in|0}} second deck and a {{cvt|0.75|in}} splinter deck. The total thickness for the outboard section of the deck would have been 8.1 in (206&nbsp;mm).{{sfn|Garzke|Dulin|1995|p=173}}

The main batteries were designed to have very heavy protection, with turret faces having {{cvt|18|in|0}} Class B mounted on {{cvt|4.5|in|0}} STS, resulting in {{cvt|22.5|in|0}} thick laminated plate. The turret sides were to have up to {{cvt|10|in|0}} Class A and turret roofs would have {{cvt|9.15|in|0}} Class B. The barbettes would have been protected by up to {{cvt|21.3|in|0}} Class A forward and {{cvt|18|in|0}} aft, while the [[conning tower]] sides would have {{cvt|18|in|0}} Class A.{{sfn|Garzke|Dulin|1995|pp=173–174}}

''Montana''{{'}}s torpedo protection system design incorporated lessons learned from those of previous US fast battleships, and was to consist of four internal longitudinal torpedo bulkheads behind the outer hull shell plating that would form a multi-layered "bulge". Two of the compartments would be liquid loaded in order to disrupt the gas bubble of a torpedo warhead detonation while the bulkheads would elastically deform and absorb the energy. Due to the external armor belt, the geometry of the "bulge" was more similar to that of the ''North Carolina'' class rather than that of the ''South Dakota'' and ''Iowa'' classes. The design of the ''Montana''{{'}}s torpedo defense system addressed a potential vulnerability of the ''South Dakota''-type system, where caisson tests in 1939 showed that extending the main armor belt that tapers to the keel to act as one of the torpedo bulkheads had detrimental flooding effects due to the belt's rigidity. ''South Dakota''{{'}}s and ''Iowa''{{'}}s systems were modified in light of these tests, and ''Iowa''{{'}}s system was also further reinforced.{{sfn|Jurens|Morss|2016|pp=289–294}} Like on the ''South Dakota'' and ''Iowa'' classes, the two outer compartments would be liquid loaded, while two inner ones be void with the lower Class B armor belt to form the holding bulkhead between them. The greater beam of the ''Montana''s would allow a higher system depth of {{cvt|20.5|ft|2}} compared to {{cvt|18.5|ft|2}} of the ''North Carolina''s.{{sfn|Garzke|Dulin|1995|pp=168–169}}