Nevada-class battleship

The Nevada-class battleships were the United States Navy's first battleship design equipped with triple gun turrets (the would be the last to carry twin turrets, armed with dual-mounted 16-inch guns), as well as introducing the "all or nothing" armor scheme in American capital ship design, in which protection of vital areas was optimized against heavy caliber guns, leaving other parts of the ship essentially unprotected. The Nevadas also introduced completely oil-fired propulsion. In armament, armor, and propulsion the Nevada class represented a considerable evolution in battleship design and, in being designed specifically to fight at extreme gunnery ranges, was actually well ahead of its time. They would be followed by the s.

The Nevadas were the first Standard-type battleships produced by the U.S. Navy Along with the, , and  classes, the standard type offered a battle line of vessels homogeneous in long-range gunnery, speed, tactical radius and damage control. The essential characteristics of the standard type were oil fuel, "all or nothing" armor, the arrangement of the main battery into four turrets, and significant deck armor providing protection against shells fired from long range. This combination of features made the Nevadas the prototype of the modern battleship. For example, the protection of the standard class battleships was not significantly revised after the Battle of Jutland, while other Navies tended to have different pre- and post-Jutland designs.

Active in the Atlantic Ocean before and during World War I, the Nevadas were deployed to protect Allied supply lines in the European war zone in 1918. Their service continued after the "Great War", though by the early 1920s they were the oldest of the main Battle Fleet units. Both were extensively modernized between 1927 and 1929. Oklahoma was sunk during the attack on Pearl Harbor in 1941 and was a total loss. Nevada beached herself during this raid to prevent blocking the harbor entrance after receiving damage, and was salvaged and modernized. She provided gunfire support for amphibious operations in the European and Pacific theaters, which included shelling German shore batteries on D-Day along with USS Texas (BB-35) and USS Arkansas (BB-33). Considered too old at the end of World War II to be kept in active service, Nevada was used as a target ship for nuclear and conventional weapons from 1946 to 1948, proving that her protection scheme was sound as she remained afloat for further target use after nuclear weapons tests in Operation Crossroads.

Design
With these ships the U.S. Navy developed a template known as the Standard-type battleship that it would use until the Washington Naval Treaty brought an end to dreadnought construction in 1922. Its essentials were consistent size and speed, oil fuel instead of coal, and a reversion to the superfiring mounting of heavy guns in four turrets that was used in the to keep the citadel compact. The decision to mount triple gun turrets proved controversial. Naval officers and engineers warned of "putting too many eggs in one basket"; that a lucky hit could disable more of the main guns than if they were carried in twin turrets and leave a ship at a disadvantage in battle. Shipbuilders warned that triple turrets could affect a ship's stability adversely because of their greater weight, especially when raised in a superfiring mounting. However, the Navy's Bureau of Construction and Repair (C&R), which designed the Nevadas, considered triple turrets necessary to save space and weight, keep the citadel at a reasonable size, and maximize the armor protection accordingly. It also eliminated the challenges of steam lines running through main gun magazines and ineffective placement of heavy guns, as occurred with midships turrets in previous classes. The Navy would use triple turrets in almost all of its subsequent battleship designs.



The Nevadas were also the first U.S. battleships to use the "all or nothing" principle of armor protection, also known as "raft body" armor. Previous battleships had armor of varying thickness depending on the importance of the area it was protecting. On the Nevadas, armored surfaces were limited to a minimum but were given the maximum thickness possible to give the most protection to critical areas such as magazines, engines and command areas and to ensure the maintenance of buoyancy. The ship's overall design, especially the triple turrets, was to reduce the length of the protected portion of the ship. Heavy deck armor was emphasized to guard against plunging fire. Citadel armor was omitted entirely in the thought that medium-heavy armor could actually be a detriment, since it could no longer afford protection against a direct hit and potentially cause enemy shells to explode and cause further damage. In short, the Nevadas were designed specifically to fight at the extreme ranges expected by gunnery experts. In that sense, they were well ahead of their time, as the Battle of Jutland in 1916 would show. While other navies distinguished between their pre- and post-Jutland capital ship designs, the U.S. Navy did not feel so compelled.

General characteristics
Nevada and Oklahoma were 583 ft long overall, with a beam at the waterline of 95.23 ft. They displaced 27500 LT at normal load and 28400 LT at deep load and had a draft of 27.65 ft at normal load and 29.5 ft at full load. Like preceding classes of American and foreign dreadnoughts, they were designed with a ram bow. From the Battle of Lissa in 1866 until shortly before World War I, ramming was thought to be an important tactic and most large warships were designed with this in mind. Ram bows and maximum dead-ahead firepower were emphasized, especially in the design of HMS Dreadnought and her immediate successors. When the design of the Nevadas was circulated through the Atlantic Fleet in the fall of 1911, many hoped that C&R would replace it with either a straight stem or a clipper bow to make the ships dryer in rough weather. Strong concerns were raised about the placement of the secondary battery in the hull. In preceding ships, which had been designed to essentially pre-dreadnought standards, these stations were extremely wet and could become untenable even in moderate weather. Although Captain Hood of the battleship USS Delaware lobbied the General Board to alleviate this potential defect in the Nevadas, the Board's response was lukewarm at best and the placement of secondary weapons retained by default. The guns near the ends of the ship were eventually removed during World War I.

Propulsion
The Nevadas were the Navy's first battleships to have oil as their primary fuel and the last to use twin-screw propulsion (all subsequent battleships would use four screws). Oil boasted greater thermal efficiency, allowed greater range per ton of fuel carried (something that would come in handy for Pacific operations, with their logistical supply challenges), and could be taken on while underway (although the technique was not perfected until after World War II), while coal-burning ships could not be refueled except in port, or (with great difficulty) at a dead stop. Oil made it far easier to raise steam, eliminated waste caused by "burning down fires" in port after docking, and did not leave any solid waste that needed to be frequently manually cleared away as coal did. Smaller boilers could be used, while forced draft and sealed fire rooms, with their corresponding drain of auxiliary power through the use of numerous ventilators, could be eliminated entirely. The subsequent weight and space savings allowed the entire propulsion plant to be combined amidships in a compartment almost the entire inside width of the ship but only 24 m long. The reduced length presented a smaller target area for enemy gunners. Oil also allowed these ships to manage with only one funnel, and reduced the number of stokers by 50 percent. Also, the backbreaking work of constant manual coal shoveling was eliminated. The savings in weight were used for extra armor protection. Side bunkers were omitted completely; fuel was stored in tanks located in the double bottom. Flood control in the event of underwater hits was also improved since there were no coal scuttle doors to spring open and thus compromise watertight integrity.

The Nevadas were virtually identical except in their propulsion machinery. Nevada and her sister were fitted with different engines to compare them 'head-to-head': Oklahoma received older vertical triple-expansion engines (she would be the last U.S. capital ship to use reciprocating machinery), while Nevada received geared Curtis steam turbines. Oklahoma's equipment made her less reliable and more vibration-prone, making her a ship the Navy wished to re-engine. In 1925, the Navy considered conversion to four double-acting two-stroke diesel engines. Because of the excessive weight of the diesels of the time, this idea was rejected. Nevada was the first US capital ship to combine steam turbines with reduction gearing, which allowed the turbines to operate in their efficient speed range, much faster than the propeller shafts, and thus overcome the high fuel consumption of direct drive turbines. Geared turbines were fitted in most subsequent US battleships, except those with turbo-electric propulsion.



Main guns
The Nevadas were equipped with ten 14 in (356 mm)/45 caliber guns. While these guns were carried over from the New Yorks, triple turrets were introduced for the lower fore and aft pair positions. This was due in part to the General Board's "disgust with the awkward five- and six-turret arrangements of the previous classes," with the corresponding confusion of fitting magazines between power plant compartments, reduction of the middle turrets' effective arcs of fire and the potential for weakening the ship's structure by the large number of deck openings required.

These guns fired a "relatively light" 1400 lb armor-piercing (AP) shell at a muzzle velocity of 2600 ft/s at a rate that ranged between 1.25 and 1.75 rounds per minute. Ballistics on this gun were based on the German doctrine of light shell and high velocity, a combination "not a good recipe for accurate shooting at the maximum range" in the view of some Navy gunnery circles. With elevation limited to 15 degrees, the maximum range was 21000 yd. Twin guns were individually sleeved but triples were not; the latter were placed on a common mounting to save space and weight, a design decision that was strongly criticized but considered necessary by C&R. Similar hoists supplied ammunition to the ships' twin and triple turrets. Two shell and three powder hoists supplied each triple turret, with the left shell hoist supplying the center gun. The powder hoists ran directly to the gun house, where the charges were transferred to enclosed powder trays.

The Navy rebuilt these guns during the ships' modernization in the late 1920s, with their chamber volumes enlarged to allow larger charges and boost muzzle velocity. Rebuilt Marks 1, 3 and 5 were reclassified as Marks 8, 9 and 10, respectively. A further conversion, the Mark 12, added chromium plating to increase barrel life. These guns were supplied with 1500 lb AP shells; with enlarged propellant charges, these could be fired without significant loss in muzzle velocity. In 1942, Nevada was also supplied with high capacity (HC) shells, with no armor-piercing capability but a maximized bursting charge for shore bombardment. Maximum elevation for these guns was increased to 30 degrees, which lengthened maximum range with AP shells to 34300 yd. With 1275 lb HC shells, maximum range grew to 34700 yd

Secondary guns
Twenty-one 5 in (127 mm)/51 caliber Mark 15 guns were installed to defend against enemy destroyers and torpedo boats. This was reduced to twelve in 1918 due to the overly-wet bow and stern positions the other nine had been occupying. During the ships' 1927-30 modernization, the 12 remaining guns were remounted in newly built unarmored casemates one deck higher to rectify this problem. The Mark 15 fired a 50 lb shell at a velocity of 3150 ft/s to a maximum range of 14400 yd at 45 degrees at a rate of seven rounds per minute and was extremely accurate, with a danger space longer than the range to the target for distances less than 3000 yd. This gun's sole drawback was a short barrel life; otherwise, the Navy considered this a highly successful weapon.

In 1942, the Mark 15 guns and the 5-inch 25 caliber guns fitted in 1927-30 (see Anti-Aircraft section) were replaced with sixteen 5-inch 38 caliber Mark 12 dual purpose guns in twin enclosed mounts. This gun fired a 55.18 lb shell to a maximum range of 17392 yd or a maximum altitude of 37200 ft at an elevation of 45 degrees. Because it was a standard weapon on nearly every major U.S. warship built between 1934 and 1945, any challenges of logistical supply were effectively minimized. As with the previous 5-inch 25 caliber guns, they were hand-loaded but power-rammed for a high rate of fire at any angle of elevation. The introduction of proximity fused anti-aircraft shells in 1943 made the 5"/38 even more potent in this capacity.

Anti-aircraft guns


Two 3 inch/50 caliber (76 mm) guns were mounted for anti-aircraft (AA) defense when the Nevadas were commissioned. This was increased to eight guns in 1925. These guns fired a 3 inch (76 mm) shell at a muzzle velocity of 1650 ft/s to a maximum range of 8800 yd and ceiling of 18000 ft at an elevation of 45.3 degrees and a rate of between eight and nine rounds per minute. During the ships' late-1920s reconstruction, the eight 3"/50s were replaced with the same number of 5 inch 25 caliber guns (127 mm). The 5"/25 was the first Navy gun designed specifically for AA use and was fitted on most U.S. capital ships and cruisers built or modernized 1926-1940. Like the later 5 inch 38 caliber gun that was derived from it, they had a high rate of fire due to being hand loaded and power rammed. They fired a 54 lb shell at a muzzle velocity of 2155 ft/s at a rate of between 15 and 20 rounds per minute to a maximum range of 14500 yd at an elevation of 45 degrees and a ceiling of 27400 ft at a maximum elevation of 85 degrees. Gunnery officers on battleships considered the 5"/25 a dual purpose weapon when these weapons were fitted and often fired them in annual surface gunfire contests with impressive results. These guns were supplemented with eight 1.1 inch (28 mm) machine cannons in two quadruple mounts in 1935.

As with the secondary weapons, all these guns were replaced on Nevada in 1942. In their place, in addition to sixteen 5"/38s in twin mounts, she carried thirty-six Bofors 40 mm guns in quad mounts and up to thirty-eight Oerlikon 20 mm cannons in single mounts. The quad 40mm Bofors fired a 1.985 lb at a rate of 120 rounds per minute per barrel nominal, 140 to 160 rounds per minute when horizontal (gravity assist), to a maximum range of 11133 yd at 45 degrees and a ceiling of 22299 ft. The 20mm Oerlikons fired a 0.271 lb shell at an average muzzle velocity of 2725 ft/s and a practical rate of between 250 and 320 rounds per minute to a maximum range of 4800 yd at 45 degrees and a ceiling of 10000 ft. By 1944, the Navy had found 20 mm shells too light to stop Japanese Kamikaze planes; this plus the higher approach speeds of these planes made these manually controlled guns obsolete. They were consequently replaced by 40 mm Bofors wherever possible.

Torpedo tubes
The Nevadas carried two 21 in (533 mm) torpedo tubes below the waterline until their conversion in the late 1920s, when they were removed. The Bliss-Leavitt 21" (533 mm) Mark 3 Model 1 torpedo designed for these tubes had an overall length of 196 in, a weight of 2059 lb and propelled an explosive charge of 210 lb of TNT to a range of 9000 yd at a speed of 27 kn

Armor
The Navy arrived at the Nevadas' "all or nothing" armor plan from a confluence of design choices rather than one overall scheme. Despite the fact that it evolved in a somewhat haphazard manner, all of its features interlocked perfectly not just for these ships but also to form a template for subsequent U.S. capital ship design. Questions had been raised about the traditional, more complex armor plan used in the. The growing range of heavier naval guns being mounted in the world’s newest dreadnoughts, matched with the improved ranging and fire control capabilities, prompted U.S. naval designers to question whether that protective scheme was still effective. Also, because of the growing ranges becoming involved in naval gunnery battles, the greatly increased chance of plunging fire had to be accounted for in protecting main deck and turret tops. As the Battle of Jutland would prove, with turret roofs and decks on both sides pierced repeatedly and three British battlecruisers blown up, this emphasis on horizontal armor was actually warranted.

Gunnery trials against the target ship USS San Marcos (ex-USS Texas (1892)) confirmed the need for a better armor suite. In designing such a system, the Nevada's team was "almost alone," without precedents from which to follow or refine. They first had to realize that belt and deck armor had to form one common "zone of immunity," with the belt setting the inner edge of this zone and the deck, the outer edge. The New Yorks featured a deck thick enough to set off an armor-piercing shell over a thinner-armored deck to catch the splinter. To maximize protection, main and splinter decks were combined into one. The armored deck was raised one level to link it directly to the top edge of the belt armor. This reduced a weak spot previously covered by the mid grade casement armor, simplified construction and increased girder strength for the hull. As all U.S. battleships already had thick armor end bulkheads, this gave the magazines, machinery and control areas one continuous armored box.

The side armor of 343 mm reached almost as high above the design waterline as it extended below. Two armored decks protected against plunging fire. The upper armored deck, 3 in thick, rested flat on the upper edge of the belt armor. One level below it, a second armored deck 1.5 in thick on flat surfaces and 2 in thick on inclines that reached to the lowere edge of the belt, protected the lower decks. The bow and stern were generally not armored, although a narrower, weaker strip of side armor was extended aft to protect the steering gear compartment. Otherwise, their only protection by the lower armored deck, which extended as far as these areas. Although heavy, the weight of the armored decks was minimized by reducing the number of main turrets from five in the New Yorks to four; this meant accepting triple mounts to minimize armored length.

The Nevadas were also the Navy's first to eliminate bunker armor, replacing it with an inboard armored bulkhead (strong enough to withstand about 100 lb (45 kg) of TNT or 190 megajoules of energy), the first use of underwater protection in the U.S. Navy.

1929–30 Modernization
In 1929 both ships went into drydock for modernization. Boiler capacity was reduced by 50 percent, with all the old boilers removed and new, more efficient ones installed. The weight saved was used to increase horizontal armor and augment the protective equipment with torpedo bulges up to 6.1 ft on both sides. This would increase the ships' beam to 105.2 ft, which with an increase in displacement to 28,500 tons meant they needed one percent more power to maintain the same speed they had previously (18,125 EHP instead of 17,874). In addition, Nevada was re-engined using the turbines that had been installed in the USS North Dakota in 1917 and removed before she was scrapped. New, unarmored casemates were built on the main deck and the 5"/51 cal guns moved there to improve their tenability in rough weather. The torpedo tubes were removed, new anti-aircraft guns and gunnery control instruments installed. Bridge structures were modified and increased and tripod masts replaced the traditional lattice masts. Longer, lighter ship's cranes were fitted and the simple derrick aft was replaced by a level luffing crane. Finally, two aircraft catapults were fitted, one on the ships' poop and the second atop C turret.

Deployment
The Nevadas were active in the Atlantic Ocean before and during World War I, deploying to the European war zone in 1918 to help protect Allied supply lines. Their service continued after the "Great War", though by the early 1920s they were the oldest of the main Battle Fleet units. Both were extensively modernized between 1927 and 1929, receiving greater elevation for their new Mark 10/45 heavy guns, modern gunfire controls in new tripod masts, and two catapults for scouting and observation airplanes. Their 5 in 51-caliber anti-destroyer guns were moved to drier locations in the superstructure and a battery of 5-inch 25-caliber anti-aircraft guns was added. Protection against shellfire, bombs, and torpedoes was improved, increasing their beam to nearly 108 ft and battle displacement to about 34000 LT. Nevada's steam turbines, prematurely aging, were replaced with far better geared turbines from the decommissioned USS North Dakota (BB-29) at this time; Oklahoma was not re-engined, but both ships were equipped with modern medium-pressure boilers.

At Pearl Harbor, Oklahoma was sunk and Nevada beached herself with light damage (which climbed to moderate damage, after a large fire in number 2 {"B"} turret a day later) to prevent blocking the harbor entrance. Nevada’s experience proved the torpedo defence system was very good, but watertight integrity on the upper decks of older warships was unlikely to be satisfactory. Oklahoma, hit by 9 torpedoes within a matter of a few minutes, capsized and was a total loss, but Nevada was salvaged and modernized again during 1942, exchanging her old secondary battery for new 5-inch 38-caliber dual-purpose twin mounts, plus numerous 40 mm and 20 mm anti-aircraft autocannons. Her superstructure was completely reconstructed in modern form, with a much-reduced conning tower. She served in both the European and Pacific theaters, providing gunfire support for amphibious operations. Nevada, along with USS Texas (BB-35) and USS Arkansas (BB-33), shelled German shore batteries on D-Day. Nevada’s final mission was as a target for nuclear and conventional weapons from 1946 to 1948.