Editing Tennessee-class battleship (section)

==Design==
[[File:USS New Mexico BB-40 1921.jpg|thumb|left|{{USS|New Mexico|BB-40|2}}, the basis for the ''Tennessee'' design]]

Design work on the ''Tennessee'' class, initially referred to as "Battleship 1916", began on 14 January 1915; the design staff used the preceding {{sclass|New Mexico|battleship|4}} as a starting point. The [[General Board]] wanted to build a battleship that departed from the [[standard-type battleship]] series, particularly in terms of armor protection against the latest {{convert|15|in|adj=on|0}} guns being fielded by European navies. They were opposed to simply developing the standard series, which incorporated relatively minor incremental improvements, but [[Secretary of the Navy]], [[Josephus Daniels]], overruled them and ordered that "Battleship 1916" would effectively repeat the ''New Mexico'' design with limited improvements.{{sfn|Friedman|1985|pp=121–122}}

At the same time that European navies had begun to adopt larger guns, they also began to develop longer-ranged [[torpedo]]es that could reach well into the expected battle distances of the day, {{convert|10000|to|14000|yd}}. Therefore, the new ship's ability to resist underwater attack—[[naval mine]]s in addition to torpedoes—became a chief concern of the designers. To ensure the ship could survive an underwater explosion, they decided to incorporate four [[torpedo bulkhead]]s, which created four voids. Of these, the inner pair would be filled with either water or [[fuel oil]], which would absorb the pressure and gas of the explosion. This system proved to be effective and it was used in many subsequent battleship designs.{{sfn|Friedman|1985|pp=122, 134}}

The ships were authorized on 3 March 1915, while design work was still ongoing; tests on the torpedo bulkhead system were completed only in February 1916. In the meantime, work had already begun on the next class, initially designated "Battleship 1917", which became the {{sclass|Colorado|battleship|4}}. This class was essentially a repeat of the ''Tennessee'' design, the only major change was the adoption of larger {{cvt|16|in|0}} guns in place of the {{cvt|14|in|0}} guns the ''Tennessee''s carried. The [[Turbo-electric transmission|turbo-electric drive propulsion system]] that was developed for the ''Colorado''s was retroactively applied to ''Tennessee'' and ''California'' in December 1915, before construction had begun on either vessel.{{sfn|Friedman|1985|pp=135–136}}

===General characteristics and machinery===
[[File:ONI identification image Tennessee class battleship.jpg|thumb|left|Recognition drawing of ''Tennessee'' in her 1943 configuration]]

The ''Tennessee''-class ships were {{convert|600|ft|1}} [[length at the waterline|long at the waterline]], {{cvt|624|ft|1}} [[length overall|long overall]], had a [[beam (nautical)|beam]] of {{convert|97|ft|5|in|abbr=on|1}}, and a [[draft (nautical)|draft]] of {{convert|30|ft|2|in|abbr=on|1}}. They [[displacement (ship)|displaced]] {{convert|32300|LT|t|0|lk=on|abbr=on}} [[standard displacement|standard]], and {{convert|33190|LT|t|0}} at [[full load displacement|full combat load]]. Under emergency conditions, additional fuel and ammunition could be stored, which significantly increased displacement to {{convert|37948|LT}}, which accordingly deepened draft to {{convert|34|ft|9.875|in|1}}.{{sfn|Friedman|1985|pp=443–444}} The ships' [[hull (watercraft)|hulls]] featured a pronounced [[clipper bow]] to handle high seas and reduce spray. A [[double bottom]] extended for the full length of the ships, and their hulls featured extensive [[watertight compartment|compartmentalization]] to reduce the risk of uncontrollable flooding; below the [[waterline]], the hull had 768&nbsp;compartments and another 180 above the line.{{sfn|Cracknell|p=200}}

The [[main deck]], the highest deck that extended for the entire length of the ship, contained much of the living space for their crews,{{sfn|Cracknell|p=201}} which included 57&nbsp;officers and 1,026&nbsp;enlisted men.{{sfn|Friedman|1985|p=443}} As built, they were fitted with two [[lattice mast]]s with [[spotting top]]s for the [[main battery]].{{sfn|Friedman 1986|p=117}} Steering was controlled by a single balanced [[rudder]].{{sfn|Cracknell|p=200}}

The ships were powered by [[turbo-electric drive]]. Eight oil-fired [[Babcock & Wilcox]] [[water-tube boiler]]s generated steam that powered two [[Westinghouse Electric Corporation|Westinghouse]] turbo-[[electric generator]]s that in turn provided power for four [[electric motor]]s that drove four 3-bladed, {{convert|14|ft|adj=on}} [[propeller|screws]]. The turbines were in separate watertight compartments, arranged fore and aft, with four boilers apiece; each boiler had its own watertight [[fire room|boiler rooms]], with two boilers on either side of the turbines. The motors were arranged in three rooms: a larger, central room for the two engines driving the inboard shafts, and one for each outboard shaft on either side. Each set of four boilers was ducted into its own [[funnel (ship)|funnel]].{{sfn|Cracknell|p=201}}

Their propulsion systems were rated at {{convert|28600|shp|lk=on}}, generating a top speed of {{convert|21|kn|lk=in}}. On speed trials, ''Tennessee'' reached a maximum of {{convert|21.38|kn}} from {{convert|29609|shp|abbr=on}}. Normal oil storage amounted to {{convert|1900|LT|0}}, but voids in the hull could be used to increase maximum emergency fuel capacity to {{convert|4656|LT}}. They had a cruising range of {{convert|8000|nmi|lk=in}} at a speed of {{convert|10|kn}}, which fell to {{convert|2500|nmi}} at {{convert|20|kn}} normally; with full emergency oil their range more than doubled, to {{convert|20500|nmi}} at 10&nbsp;knots and {{convert|9700|nmi}} at {{convert|18|kn}}.{{sfn|Friedman|1985|p=443}}{{sfn|Friedman 1986|p=117}}

===Armament===
[[File:USS California (BB-44) after turrets.jpg|thumb|''California''{{'}}s aft turrets]]
The ships were armed with a main battery of twelve [[14"/50 caliber gun|{{convert|14|in|adj=on|0}} /50 caliber Mark IV guns]]<ref group=Note>A 50 [[caliber (artillery)|caliber]] gun has a length 50 times its bore diameter.</ref> in four triple [[gun turret|turrets]], placed on the centerline in [[superfire|superfiring pairs]] forward and aft of the [[superstructure]]. Unlike earlier American battleships with triple turrets, these mounts allowed each barrel to elevate independently.{{sfn|Friedman 1986|p=117}} Since ''Tennessee'' and ''California'' were laid down after the [[Battle of Jutland]] of mid-year 1916, which demonstrated the value of very long-range [[plunging fire]], their main battery turrets were modified while still under construction to allow elevation to 30&nbsp;degrees.{{sfn|Friedman|1985|p=135}} This provided a maximum range of {{convert|35100|yd}} with the standard {{convert|1500|lb|adj=on}} [[armor-piercing shell]], which was fired with a [[muzzle velocity]] of {{cvt|2625|ft/s}}. With the lighter {{cvt|1275|lb}} high-capacity shell, the muzzle velocity increased to {{cvt|2825|ft/s}} for a correspondingly greater range of {{cvt|36650|yd}}.{{sfn|Cracknell|p=205}} The guns suffered from excessive dispersion of shot, which was eventually discovered to have been caused by overly lengthy [[Chamber (firearms)|chambers]], which allowed a gap between the shell and the propellant charges. The problem was eventually corrected with the Mark VII gun.{{sfn|Friedman|2011|p=163}}

The [[secondary armament|secondary battery]] consisted of fourteen [[5"/51 caliber gun|{{convert|5|in|adj=on|0}} /51 caliber guns]], ten of which were mounted in individual [[casemate]]s clustered in the superstructure [[amidships]] at 01 deck level, one deck higher than the main deck. Six of the guns were arranged to fire forward and four were pointed aft. The remaining four guns were placed in open pivot mounts another deck higher at 02 level; two were placed abreast the conning tower and the others placed on either side of the funnels. Initially, the ships were to have been fitted with twenty-two of the guns, but experiences in the [[North Sea]] during [[World War I]] demonstrated that the additional guns, which would have been placed in the hull, would have been unusable in anything but calm seas. As a result, the casemates were plated over to prevent flooding.{{sfn|Friedman 1986|p=117}}{{sfn|Cracknell|p=205}} The guns were the Mark VIII type, which had a muzzle velocity of {{cvt|3150|ft/s}} firing a {{cvt|50|lb}} shell.{{sfn|Friedman|2011|p=185}}

The battleships carried four [[3"/50 caliber gun|{{convert|3|in|adj=on|0}}/50 caliber Mark X guns]] for anti-aircraft defense. These guns were located on the 02 deck, with two on either side of the boat cranes and the other two abreast of the mainmast. The guns fired a {{cvt|13|lb}} shell at a velocity of {{cvt|2700|ft/s}}. They also carried a variety of other guns, including four 6-pounder [[saluting gun]]s and a 3-inch Mark XI [[field gun]] and several [[machine gun]]s for use by [[landing party|landing parties]].{{sfn|Friedman|2011|pp=193–194}}{{sfn|Cracknell|pp=205, 207}}

In addition to their gun armament, the ''Tennessee''-class ships were also fitted with a pair of {{convert|21|in|adj=on|0}} [[torpedo tube]]s, with one mounted submerged in the hull on each [[Broadside (naval)|broadside]].{{sfn|Friedman 1986|p=117}} They were supplied with [[Bliss-Leavitt torpedo]]es of the Mark VII type; these carried a {{cvt|321|lb}} [[warhead]] and had a range of {{cvt|12500|yd}} at a speed of {{cvt|27|kn}}.{{sfn|Friedman|2011|pp=342–343}}

===Armor===
Their main [[armored belt]] was {{cvt|8|–|13.5|in|0}} thick and was approximately {{cvt|18|ft}} wide, half of which was above the waterline. The thicker armor protected the ships' vitals, including the ammunition magazines and propulsion machinery spaces, extending from the forwardmost [[barbette]] to the aftmost barbette; the stern received lighter armor plating. Both ends of the main belt were capped by armored transverse [[bulkhead (partition)|bulkheads]] that were 13.5&nbsp;in thick. The main armored deck was up to {{cvt|3.5|in|0}} thick, and it was connected to the top of the main belt, running between the transverse armored bulkheads. A second armor deck that was {{cvt|2.5|in|0}} thick was placed below the main deck; further aft, where it constituted the only horizontal protection, it increased in thickness to 5&nbsp;in. On the ships' bows, the lower armor deck was increased to 3&nbsp;in.{{sfn|Friedman 1986|p=117}}{{sfn|Cracknell|pp=201–202}}

The main battery gun turrets had {{cvt|18|in|0}} thick faces, {{cvt|10|in|0}} thick sides, {{cvt|9|in|0}} rears, and {{cvt|5|in|0}} roofs; [[teak]] backing was used to cushion the structures from shell impacts. The turrets were mounted atop {{cvt|13|in|0}} barbettes. Their [[conning tower]]s had {{cvt|16|in|0}} thick sides with {{cvt|6|in|0}} thick roofs. The armored [[coaming]]s for the funnel uptakes were 9&nbsp;in thick.{{sfn|Friedman 1986|p=117}}{{sfn|Cracknell|p=202}}

===Modifications===
[[File:Vought UO-1 on float NAN3-60.jpg|thumb|left|One of ''Tennessee''{{'}}s [[Vought UO-1]]s]]
The ''Tennessee''s underwent a series of minor modifications to their secondary and anti-aircraft armament through the 1920s and 1930s. In 1922, ''Tennessee'' had the two 5-inch guns abreast the mainmast removed and four more 3-inch guns installed, two of which were placed where the 5-inch guns had been. The other two were placed behind the forward 5-inch mounts. All eight guns were removed in 1928 and replaced with eight [[5"/25 caliber gun|5-inch /25 caliber anti-aircraft guns]].{{sfn|Cracknell|pp=205–206}} ''California'' was similarly rearmed during a refit in 1929–1930.{{sfn|Breyer|p=226}} Eight [[M2 Browning|.50 caliber machine guns]] were added, six to the roofs of the spotting tops, two on the foremast and four on the mainmast. The other two guns were placed on pedestals on either side of the foremast. ''Tennessee'' had two of the 3-inch guns returned in 1940, placed on either side of the [[bridge wing]]s.{{sfn|Cracknell|p=206}}

Other changes included the installation of aircraft-handling equipment. ''California'' had an [[aircraft catapult]] installed on her aft superfiring turret and she received three [[Vought UO-1]] [[seaplane]]s for reconnaissance and fire direction. Two years later, ''Tennessee'' was similarly modified, though her catapult was located on the [[fantail (ship)|fantail]]. In the early 1930s, she received a second catapult on her aft turret, and at some point ''California'' also had a catapult fitted to her fantail. During their 1943 reconstruction, the turret-mounted catapults were removed and both ships were fitted with just a catapult on the fantail.{{sfn|Cracknell|p=201}}{{sfn|Evans}}

[[File:USS Tennessee (BB43) 1943.jpg|thumb|''Tennessee'' after 1943 modernization]]

Both ships were extensively reconstructed and modernized after being damaged during the [[attack on Pearl Harbor]] in December 1941. New [[anti-torpedo bulge]]s were installed and their internal compartmentalization was improved to strengthen their resistance to underwater damage. The ships' superstructures were completely revised, with the old heavily armored conning tower being removed and a smaller tower was erected in its place to reduce interference with the anti-aircraft guns' fields of fire. The new towers had been removed from one of the {{sclass|Brooklyn|cruiser|1}}s that had recently been rebuilt. The foremast was replaced with a tower mast that housed the bridge and the main battery director, and their second funnels were removed, with those boilers being trunked into an enlarged forward funnel.{{sfn|DANFS ''Tennessee''}}{{sfn|Friedman|1980|p=92}} Horizontal protection was considerably strengthened to improve their resistance to air attack; 3 inches of [[special treatment steel]] (STS) was added to the deck over the magazines and {{convert|2|in}} of STS was added elsewhere.{{sfn|Friedman|1985|p=444}}

Their weapons suite was also overhauled. Both ships received air-search [[radar]] and fire-control radars for their main and secondary batteries, the latter seeing the mixed battery of 51-caliber and 25-caliber 5-inch guns replaced by a uniform battery of sixteen [[5"/38 caliber gun|5-inch/38 caliber guns]] in eight twin mounts. These were controlled by four [[Mark 37 Gun Fire Control System|Mk 37 directors]]. The light anti-aircraft battery was again revised, now consisting of ten quadruple [[Bofors 40 mm Automatic Gun L/60|{{cvt|40|mm}} Bofors guns]] and forty-three 20&nbsp;mm Oerlikons, all in single mounts.{{sfn|Breyer|p=226}}{{sfn|DANFS ''Tennessee''}} The changes doubled the ships' crew, to a total of 114&nbsp;officers and 2,129&nbsp;enlisted men. During her final refit in January 1945, ''Tennessee'' received an SP air search radar and a Mark&nbsp;27 [[fire control radar]].{{sfn|Friedman|1985|pp=358, 444}}