North Carolina-class battleship

North Carolina steaming c. 1945–1947
Class overview
Name	North Carolina class battleship
Builders	New York Naval Shipyard (North Carolina) Philadelphia Naval Shipyard (Washington)
Operators	United States Navy
Preceded by	South Dakota class (1920) (planned) Colorado class (actual)
Succeeded by	South Dakota class (1939)
Cost	$60,000,000 each
In service	1941–47
Completed	2
Retired	2
Preserved	1
General characteristics
Class and type	Battleship
Displacement	1942: 36,600 long tons (37,200 t) (standard) 44,800 long tons (45,500 t) (full load) 1945: 46,700 long tons (47,400 t) (North Carolina full load) 45,370 long tons (46,100 t) (Washington full load)
Length	North Carolina: 728 ft 8.625 in (222.11348 m) overall 713 ft 5.250 in (217.45575 m) waterline Washington: 728 ft 11.625 in (222.18968 m) overall 713 ft 8.000 in (217.52560 m) waterline
Beam	108 ft 3.875 in (33.01683 m) maximum 104 ft 6.000 in (31.85160 m) waterline
Draft	North Carolina: 35 ft 6.000 in (10.82040 m) maximum Washington: 34 ft 9.000 in (10.59180 m) maximum
Propulsion	four sets of General Electric geared turbines, providing 121,000 shp ahead and 32,000 astern eight Babcock & Wilcox three drum express type boilers fitted with two furnaces and double uptakes
Speed	1941: 28 knots (32 mph; 52 km/h) 1945: 26.8 knots (30.8 mph; 49.6 km/h)
Endurance	1941: 17,450 nmi (20,080 mi; 32,320 km) at 15 knots (17 mph; 28 km/h) 1945: 16,320 nmi (18,780 mi; 30,220 km) at 15 knots 5,740 nmi (6,610 mi; 10,630 km) at 25 knots (29 mph; 46 km/h)
Crew	Design: 108 officers, 1,772 men 1945: 144 officers, 2195 men 1947, North Carolina: 135 officers, 1,639 men 1947, Washington: 146 officers, 1843 men
Sensors and processing systems	varied greatly during the war, see the "Electronics" section
Armament	9 × 16 in (410 mm)/45 caliber Mark 6 guns 20 × 5-inch/38 caliber Mark 12 guns Smaller weapons, like Bofors 40 mm or Oerlikon 20 mm, varied greatly; see the "Smaller weaponry" section
Armor	Belt: 12.0" on 0.75" STS (305 mm on 19 mm), inclined 15 degrees, tapering to 6.6" on 0.75" STS (168 mm on 19 mm) at lower edge Barbettes: centerline forward: 14.7" (373 mm) sides 16.0" (406 mm) centerline aft 11.5" (292 mm) Turrets: face plates 16.0" (406 mm) sides 9.8" (249 mm) back plates 11.8" (300 mm) roof plates 7.0" (178 mm) Secondary guns: mounts 1.95" (50 mm) magazines 1.95" (50 mm) Decks: Centerline main 1.45" (37 mm) second 1.4" + 3.6" (36 mm + 91 mm) third 0.62" (16 mm) total 7.07" (180 mm) Outboard 1.45" (37 mm) second 1.4" + 4.1" (36 mm + 104 mm) third 0.75" (19 mm) total 7.70" (196 mm) Conning tower: centerline sides 14.7" (373 mm) beam sides 16.0" (406 mm) roof sides 7.0" (178 mm) bottom plates 3.9" (99 mm) communication tube 14.0" (356 mm)
Aircraft carried	Vought OS2U Kingfisher Curtiss SC-1 Seahawk
Notes	Extensively detailed information and drawings are available from Garzke and Dulin, Battleships: United States Battleships in World War II, 62–69

The North Carolina class was a series of two fast battleships, North Carolina and Washington, built for the United States Navy in the late 1930s. The navy originally was uncertain whether the ships should be fast enough to counter the Japanese Kongō class which was believed by the United States to be capable of 26 knots (30 mph; 48 km/h), or should sacrifice speed for additional firepower and armor. The Washington, First London and Second London Naval Treaties did not allow all these objectives to be achieved within the treaty limits, and the navy considered over fifty designs before one was chosen.

Towards the end of this lengthy design period, the General Board of the United States Navy declared that it favored design "XVI-C", which called for a speed of 30 knots (35 mph; 56 km/h) and a main battery of nine 14 in (360 mm)/50 caliber Mark B guns. The board believed that such ships could fulfill a multitude of roles, as they would have enough protection to be put into a battle line while also having enough speed to escort aircraft carriers or engage in commerce raiding. However, the acting Secretary of the Navy authorized a modified version of a different design, "XVI", which in its original form had been derided as "not being a true battleship" and had been rejected by the General Board. This called for a 27-knot (31 mph; 50 km/h) ship with twelve 14 inch rifles in quadruple turrets and protection against guns of the same caliber. In a major departure from traditional American design practices, "XVI" accepted lower speed and protection in exchange for maximum firepower. After construction had begun, the Navy, concerned over Japan's refusal to commit to the caliber limit of the Second London Naval Treaty, invoked the "escalator clause" of that pact and increased the caliber of the main armament. Nine 16 in (410 mm)/45 Mark 6 caliber guns were specified in place of the twelve 14 inch guns of the original design, but it was too late to increase the armor.

Both North Carolina and Washington saw extensive service during World War II in a variety of roles, primarily in the Pacific theater. North Carolina frequently acted as an escort for the fast carrier task forces, and also conducted shore bombardments. In 1942, during the naval battle of Guadalcanal, Washington sank the Japanese battleship Kirishima in a furious night engagement. She also served as a carrier escort. In February 1943, she collided with the battleship Indiana and suffered severe damage to her bow. Following repairs, Washington rejoined her sister for the Battle of the Philippine Sea. After the end of the war, both ships took part in Operation Magic Carpet, the withdrawal of American military personnel from overseas deployments. The vessels were laid up in the reserve fleet until the early 1960s, when North Carolina was sold to her home state as a museum ship, and Washington was broken up for scrap.

Design

"A"–"L"

The General Board began preparations for a new class of battleships in May–July 1935. Three design studies were submitted to them: "A" would be 32,150 long tons (36,010 short tons; 32,670 t) armed with nine 14 in (360 mm) guns in triple turrets—all forward of the bridge—capable of 30 knots (35 mph; 56 km/h), and armored against 14-inch shells; "B" and "C" would both be over 36,000 long tons (40,000 short tons; 37,000 t), able to reach 30.5 knots (35.1 mph; 56.5 km/h) and armored against 14-inch shells—the major difference between the two was the planned main battery, as "B" had twelve 14-inch guns in triple turrets, while "C" had eight 16 in (410 mm)/45-caliber guns in dual turrets. "A" was the only one to remain within the 35,000-long-ton (39,000-short-ton; 36,000 t) displacement limit set in the 1922 Washington Naval Treaty. When the Bureau of Ordnance introduced a "super-heavy" 16 in shell, the ships were redesigned ("A1", "B1" and "C1") in an attempt to provide protection against it; "A1" was only 500-long-ton (510 t; 560-short-ton) below the 35,000-ton limit, while the other two were close to 40,000-long-ton (41,000 t; 45,000-short-ton).

Proposed scheme "A"

Although these original three studies were all fast battleships, the General Board was not definitively committed to the higher maximum speeds. It posed questions to the Naval War College, asking for their opinion as to whether the new class should be a "conventional" 23-knot (26 mph; 43 km/h) ship with an eight-nine, 16-inch main battery, or rather one akin to "A", "B" or "C".

Five more design studies were produced in late September, "D" through "H"; they had characteristics of 23–30.5 knots, eight or nine 14- or 16-inch guns, and a standard displacement between 31,500 long tons (35,300 short tons; 32,000 t) and 40,500 long tons (45,400 short tons; 41,100 t). "D" and "E" were attempts at fast battleships with 16-inch guns and protections against the same, but their displacement was greater than the Washington Naval Treaty allowed. "F" was a radical attempt at a hybrid battleship-carrier, with three catapults mounted fore and eight 14-inch guns aft. Reportedly it was favored by President Franklin Delano Roosevelt, but as aircraft launched from catapults were necessarily inferior to most carrier- or land-based aircraft because of their floats, nothing came of the design. "G" and "H" were slower 23-knot ships with nine 14-inch guns; in particular, "H" was thought to be a very well balanced design by the Preliminary Design section of the Bureau of Construction and Repair. However, the General Board now desired "fast, multipurpose ships", which "G" and "H" were not.

These studies demonstrated the difficulty the designers faced. With a displacement of 35,000 tons, there were two basic choices: a ship similar to "A1" which was faster (30 knots) but more lightly armed and armored than contemporary battleships or one which was slower but armed with heavier guns—although fitting in protection against 16 in guns would be extremely difficult. Preliminary Design drew up five more studies in October, "J", "J1", "K", "L" and "M", based upon either "A" with additional armor or a scaled-down "B"; all utilized 14 in guns and called for 30 or 30.5 knots. The first two would use four turrets, but it was felt that an arrangement with these were too heavy, forcing an unacceptable amount of armor to be sacrificed. "K" was the aforementioned development of "A1", having a 15 in (380 mm) belt and 5.25 in (133 mm) deck and a 19,000–30,000 yd (11–17 mi; 17–27 km) immune zone against the United States' super-heavy 14 in shell. While "K" was liked within the Navy, its designed standard displacement of 35,000 tons left little room for error or any modifications and improvements to the design. Both "L" and "M" would use quadruple turrets to save weight (similar to the French Dunkerque) while still mounting 12 guns; the only difference between the two was that "M" saved 200 long tons (200 t; 220 short tons) by having one turret aft rather than all three fore. This design change increased the deck armor to 4.75 in (121 mm), rather than the 4.5 in (110 mm) in "L". Cuts to various parts of the armor were accepted to ensure that the design was under the treaty limit; even so, both were close, and "L" was 45 long tons (46 t; 50 short tons) over.

Many officers in the United States Navy supported the construction of three or four battlecruiser-type ships for carrier escorts and to counter Japan's Nagato class. These included the acting Secretary of the Navy and Chief of Naval Operations Admiral William Standley, the president of the Naval War College Admiral William S. Pye, a small majority (9–7) of senior officers at sea, and five of six line officers engaged in strategic planning as part of the War Plans Division, although at least one officer believed that an aerial attack would also be capable of sinking the Nagatos. With the above recommendations, the General Board selected "K" to undergo further development.

Over the coming months, at least 35 different designs were proposed. All numbered with Roman numerals, the first five ("I"–"V", variations upon "K") were completed on 15 November 1935. They were the first to employ "paper" weight reductions: not counting certain weights in the ship's 35,000 long ton limit that were not specifically part of the definition of standard displacement. In this case, even though there was designed storage room for 100 shells per main battery gun and an extra 100 rounds, the latter's weight did not figure toward the treaty-mandated limit.

"I"–"XVI-D"

These designs varied greatly in everything but their standard displacements and speeds; every design beside "II" (35,743 long tons (36,317 t; 40,032 short tons)) called for 35,000 long tons, and only five planned for a top speed of under 27 knots (31 mph; 50 km/h)—of those, only one was lower than 26.5 knots (30.5 mph; 49.1 km/h): "VII", with 22 knots (25 mph; 41 km/h). "VII" returned to a lower speed to obtain more firepower (twelve 14 in guns in triple turrets) and protection; as such, the design called for only 50,000 shaft horsepower (shp) and a length of only 640 ft (200 m)—most others were 710 ft (220 m) or 725 ft (221 m), although six had lengths between 660 ft (200 m) and 690 ft (210 m). The first eight designs ("I"–"IV-C") carried nine 14 in guns, but many other combination were tried, including eight 14 or 16 in guns in two quadruple turrets, eight 14 in guns in four dual turrets ("VIA" and "VIB"), and ten, eleven or twelve 14 in guns.

Proposed design "XVI", more similar to the final design

The "XVI" version of 20 August 1936 was a 27-knot, 714 ft (218 m)-long ship that the Bureau of Ordnance decided had many problems. Model tests showed that at high speeds, waves generated by the design of the hull would leave some lower parts of the ship uncovered—including the magazines. To complicate the issue, the Bureau found that low or underwater shell hits could be a large problem when fighting at ranges between 60,000 ft (11 mi; 18 km) and 90,000 ft (17 mi; 27 km). Other problems included a fear that the ship's defense against aircraft-dropped bombs was inadequate because, in the Bureau's view, the formula used to calculate its effectiveness was not realistic, and that a tapering of a fore bulkhead below the waterline was a bad idea because of the underwater shell hit problems; the mostly unarmored bow could easily be penetrated by these. The solutions for these issues were all impractical; added patches of armor around the magazines could neutralize the torpedo-defense system's effectiveness, and deepening the belt near the bow and stern would put the ships over the 35,000 long ton limit.

To address these problems, a final set of designs, "XVI-B"–"XVI-D", was put forth by Preliminary Design in October 1936. They were modifications of "XVI"—a design derided as "not being a true battleship"—that was 714 ft. long, had twelve 14 in guns in three quadruple turrets, a belt of 11.2 in (280 mm) sloped at 10°, and a deck 5.1 in (130 mm) to 5.6 in (140 mm) think. In the final set, length was fixed at 725 ft (221 m) for greater speed, but this meant only eleven 14 in guns could be mounted with a thin 10.1 in (260 mm) belt. Alternatively, one gun could be traded for a 13.5 in (340 mm) belt, and another could be swapped for a 30-knot speed and one more tenth of an inch of belt armor; this became design "XVI-C". The General Board liked "XVI-C" very much, seeing in it a ship that had enough protection to fight—and survive—in a battle line formed with the older battleships while also having enough speed to operate in a detached wing with, for example, aircraft carrier or cruiser commerce raiding groups.

North Carolina seen from the air on 17 April 1942

However, one member of the Board, Admiral Joseph Reeves—who had previously been one of the principal developers of the United States' aircraft carrier strategy—disliked "XVI-C" because he believed that it was not fast enough to work with the 33-knot (38 mph; 61 km/h) fast carriers, and it was not powerful enough to justify its cost. Instead, he advocated a development of the previously-rejected "XVI", adding additional underwater protection and patches of armor within the ship to make the magazines immune to above- and below-water shell hits from 19,000 yd (11 mi; 17 km) and beyond. The overall immune zone's outer limit was increased from 28,200 yd (16.0 mi; 25.8 km) to 30,000 yd (17 mi; 27 km). After further revisions, Reeves went to Admiral William Standley, the Chief of Naval Operations and the acting Secretary of the Navy, who approved "XVI" in its newly modified form over the hopes of the General Board, who still thought that "XVI-C" should be built. Standley's only addition to the characteristics was that a switch from quadruple 14 in to triple 16 in turrets be possible if the "escalator clause" in the Second London Naval Treaty was invoked. This provision allowed the signatory countries—France, the United Kingdom and the United States—to raise the 14 in limit to 16 in if Japan or Italy still refused to sign after 1 January 1937. The United States invoked this in March 1937 and used the larger guns in the North Carolinas.

Describing the convoluted design process the North Carolina class went through, author Norman Friedman in U.S. Battleships: A Design History offered this commentary:

The point of this rather long and erratic design history [described in preceding pages of the book] is that, although one might see the North Carolinas [as actually built] in several of these designs, that was not in fact so. The General Board was never entirely sure of what it was willing to give up to achieve some kind of ship within the treaty-limited displacement. As its membership changed, moreover, so did its ideas. The fast capital ship with nine guns, and a speed of 30 knots, yet having good protection, was ultimately rejected in favor of a ship that sacrificed both speed and protection for firepower, a combination unprecedented in American capital ship development.

Specifications

A cut-away diagram of the 16 in turrets onboard the North Carolina class

Armament

The two North Carolinas were principally armed with nine 16-inch (410-millimetre)/45 caliber (cal) Mark 6 and twenty 5-inch (130-millimetre)/38 cal Mark 28 Mod 0 guns. Their lighter armament consisted of varying numbers of 1.1-inch (28-millimetre), .50 caliber machine guns, Bofors 40 mm and Oerlikon 20 mm.

Main battery

Mounted on both the North Carolina class and the follow-up South Dakota class, the nine 16 in/45 were improved versions of the guns mounted on the Colorado-class battleships, hence the designation of "Mark 6". A major alteration from the older guns was the Mark 6's ability to fire a new 2,700-pound (1,200-kilogram) armor piercing (AP) shell developed by the Bureau of Ordnance. At full charge with a brand-new gun, the heavy shell would be expelled at a muzzle velocity of 2,300 f/s (701 m/s); at a reduced charge, the same shell would be fired at 1,800 f/s (549 m/s). Barrel life—the approximate number of rounds a gun could fire before needing to be relined or replaced—was 395 shells when using AP, although if only practice shots were used this figure was significantly higher: 2,860. Turning at 4 degrees a second, each turret could train to 150 degrees on either side of the ship. The guns could be elevated to a maximum of 45 degrees; turrets one and three could depress to -2 degrees, but due to its superfiring position, turret two could only depress to 0 degrees.

Each gun was 736 inches (18,700 millimetres) long overall; its bore and rifling length were 720-inch (18,000-millimetre) and 616.9-inch (15,670-millimetre), respectively. Maximum range with the heavy AP shell was obtained when the gun was elevated to its highest possible point, 45 degrees: 36,900-yard (21.0-mile; 33.7-kilometre). At the same elevation a lighter (1,900-pound (860-kilogram)) high capacity (HC) shell would travel 40,180-yard (22.83-mile; 36.74-kilometre). The guns weighed 192,310 lb (87,230 kg; 86 LT) not including the breech; the turrets weighed slightly over 1,400-long-ton (1,400-tonne; 1,600-short-ton).

When firing the same shell, the 16 in/45 Mark 6 had a slight advantage over the 16 in/50 Mark 7 when hitting deck armor—a shell from a 45 cal gun would be slower, meaning that it would have a steeper trajectory as it descended. At 35,000 yards (20 miles; 32 kilometres), a shell from a 45 cal would strike a ship at an angle of 45.2 degrees, as opposed to 36 degrees with the 50 cal.

Secondary battery

A 2008 shot of North Carolina, showing the after two 5 in guns

The North Carolinas carried ten twin enclosed base ring mounts' worth of 5 in/38 caliber Mark 28 Mod 0 guns. Originally designed to be mounted upon destroyers built in the 1930s, it was so successful that it was added to a myriad of American ships during the Second World War, including every major ship type and many smaller warships constructed between 1934 and 1945. It was considered to be "highly reliable, robust and accurate" by the Navy's Bureau of Ordnance.

The 5 in/38 functioned as a dual purpose weapon; that is, it was able to fire at both surface and air targets with reasonable degrees of success. However, this ability did not detract from the performance of the gun's anti-air abilities; as established during 1941 gunnery tests conducted onboard North Carolina, the gun possessed the ability to consistently shoot down aircraft flying at 12,000 to 13,000 feet (2.3 to 2.5 miles; 3.7 to 4.0 kilometres), which was twice as far as the effective range of the earlier single purpose 5 in/25 anti-air gun.

Each 5 in/38 weighed almost 4,000-pound (1,800-kilogram) without the breech; the entire mount weighed 156,295-pound (70,894-kilogram). It was 223.8-inch (5,680-millimetre) long overall, had a bore length of 190-inch (4,800-millimetre), and had a rifling length of 157.2-inch (3,990-millimetre). The gun could fire shells at about 2,500–2,600 ft/s (762–792 m/s); about 4,600 could be fired before the barrel needed to be replaced. Minimum and maximum elevations were -15 and 85 degrees, respectively. The guns' elevation could be raised or lowered at about 15 degrees per second. The mounts closest to the bow and stern could aim from -150 to 150 degrees; the others were restricted to -80 to 80 degrees. They could be turned at about 25 degrees per second.

Smaller weaponry

40 mm guns aboard Hornet in 1945

The remaining weaponry onboard the two North Carolinas was composed of differing numbers of 1.1-inch (28-millimetre), .50 caliber machine guns, Bofors 40 mm and Oerkilon 20 mm guns. Although the ships were originally designed to carry only four quadruple 1.1 in and twelve .50 caliber, this was greatly increased and upgraded during the war.

On both ships, two more quadruple sets of 1.1 in guns were added in place of two searchlights amidships. After she was torpedoed in 1942, North Carolina had these removed and ten quadruple sets of 40 mm guns added. Fourteen were present by June 1943, while a fifteenth mount—on top of the third main turret—was added that November. Washington retained her six 1.1 in quads until the middle of 1943, when ten quad 40 mm guns replaced them. By August, she had fifteen. The two ships carried these through to the close of the war.

Although each .50 caliber machine gun was scheduled for replacement by one 20 mm gun—the former not having the range or power needed to combat modern aircraft—nothing immediately came of the proposal. In fact, both North Carolina and Washington carried 20 mm and .50 caliber guns for most of 1942. In April, North Carolina had, respectively, forty and twelve, while Washington had twenty and twelve. Two months later, the number of 20 mm guns remained the same, but 12 .50 caliber guns had been added. By September, Washington had twenty more 20 mm guns added, for a total of forty, but five were removed—along with all of the .50 caliber guns—shortly thereafter when two quadruple sets of 1.1 in guns were added. In her refit after being torpedoed, North Carolina had an additional six 20 mm guns added and all of her .50 caliber weapons removed. Washington had sixty-four 20 mm weapons by April 1943—prior to one single mount being replaced by a quadruple mount—North Carolina had fifty-three by March 1944. In April 1945, North Carolina was assigned to have fifty-six 20 mm, while Washington was assisgned seventy-five. In August 1945, the ships both had eight twin 20 mm mounts; North Carolina also carried twenty single, while Washington carried one quad and sixty-three single.

Electronics

Washington's tower foremast, seen on 18 August 1942 at the New York Navy Yard; note the SG surface search radar

Both North Carolina and Washington, designed prior to radar, were originally fitted with many fire-control and navigational optical range-finders. The former lasted until 1944, when it was replaced by a Mark 27 microwave radar—though it was supplemented by a Mark 3 main armament fire control radar; the latter was removed in favor of 20 mm guns sometime between the end of 1941 and mid-1942. In addition, the ships were commissioned with two Mark 38 directors and were originally fitted with a CXAM radar air search, two Mark 3s and three Mark 4 secondary armament.

By November 1942, North Carolina had an additional Mark 4 and a SG surface search radar added. The normal battleship configuration was present aboard North Carolina in April 1944, with SK and SG radars (air and surface search, respectively), a backup SG, and Mark 8s to direct her main battery. All of the Mark 4s remained for the secondary battery, and one of the older Mark 3s was still present, possibly as a backup for the Mark 8s. An SK-2 dish replaced the older SK radar and Mark 12s and 22s superseded the Mark 4s in September of that year. Aside from never receiving an SK-2, Washington was the recipient of similar upgrades.

Both ships underwent extensive refits near the end or after the war; North Carolina received a secondary air search set (SR) and a SCR-720 zenith search radar on the forward funnel. At the end of the war, she had an SP surface-search, a SK-2 air-search, a Mark 38 main battery fire control system with Mark 13 and 27 radars, a Mark 37 secondary battery fire control system with Mark 12, 22 and 32 radars, and a Mark 57 smaller weaponry fire control system, with a Mark 34 radar. Washington had a SK fore and a SR aft, a SG both fore and aft, and a TDY jammer present in March 1946.

Propulsion

The North Carolina class ships were equipped with four General Electric geared turbines and eight Babcock & Wilcox three-drum express type boilers. The ships' powerplant incorporated a several recent developments in turbine equipment, including double helical reduction gears and high-pressure steam technology. North Carolina's boilers supplied steam at 575 pounds per square inch and as hot as 850 °F (454 °C). To meet the design requirement of 27 knots, the engine system was designed to supply 115,000 shaft horsepower (shp), but with the new technology, this was increased to 121,000 shp. Despite this increase, the maximum speed for the ships did not change, since the modifications to the powerplant were incorporated later in the design process. The turbines that had already been installed could not fully take advantage of the higher pressure and temperature steam, and so the level of efficiency was not as high as it should have been. When going astern, the engines provided 32,000 shp.

North Carolina's second engine room under construction

The engine system was divided into four engine rooms, all on the centerline of both ships. Each room contained a turbine and two boilers, without any division between the boilers and turbines. This was done to limit the risk of capsizing should the ship sustain heavy flooding in the engine rooms. The engine rooms alternated in their layout: the first and third engine rooms were arranged with the turbine on the starboard side and its corresponding boilers on the port, this was reversed in the second and fourth rooms. The forward-most engine room powered the starboard outer shaft, the second turbine drove the outer screw on the port side, the third engine supplied power to the inner starboard propeller, and the fourth turbine drove the port-side inner screw. All four screws had four blades; the two outer propellers were 15 ft 4 in (4.674 m) in diameter and the inner pair were 16 ft 7.5 in (5.067 m) wide. Steering was controlled by a pair of rudders.

At the time of their commissioning, the ships had a top speed of 28 knots (32 mph; 52 km/h), though by 1945, with the addition of other equipment, such as anti-aircraft weaponry, their maximum speed was reduced to 26.8 knots (30.8 mph; 49.6 km/h). The increases in weight also reduced the ships' cruising range. In 1941, the ships could steam for 17,450 nautical miles (32,320 km; 20,080 mi) at a cruising speed of 15 knots (17 mph; 28 km/h); by 1945, the range at that speed was reduced to 16,320 nmi (30,220 km; 18,780 mi). At 25 knots (29 mph; 46 km/h), the range was considerably lower, at 5,740 nmi (10,630 km; 6,610 mi).

Electrical power was supplied by eight generators. Four were turbo-generators designed for naval use; these provided 1,250 kilowatts each. The other four were diesel generators that supplied 850 kilowatts each. Two smaller diesel generators—each provided 200 kilowatts—supplied emergency power should the main system be damaged. Total electrical output was 8,400 kilowatts, not including the emergency generators, at 450 volts on an alternating current.

Armor

North Carolina and Washington incorporated "all or nothing" armor which weighed 41% of the total displacement; it consisted of an "armored raft" that extended from just forward of the first gun turret to just aft of the rear gun turret. They had a main armored belt that was 12 in (300 mm) thick amidships, inclined at 15°, and backed by 0.75 in (19 mm) Special Treatment Steel (STS). This tapered down to 6 in (150 mm) on the lower edge of the belt. The ships had three armored decks; the main deck was 1.45 in (37 mm) thick, the second, thickest deck was 5 in (130 mm), and the third and thinnest deck was 0.62 in (16 mm) thick. The first deck was designed to cause delay-fuzed projectiles to detonate, while the thicker second belt would protect the ships' internals. The third deck was intended to protect against shell splinters that might have penetrated the second deck; it also acted as the upper support for the torpedo bulkheads. The conning tower was connected to the armored citadel by a 14 in (360 mm) thick communications tube. Armor thickness for the conning tower itself ranged from 16 in on both sides to 14.7 in (370 mm) on the front and rear. The roof was 7 in thick and the bottom was 3.9 in (99 mm) thick.

The main battery turrets were heavily armored: the turret faces were 16 in (410 mm) thick, the sides were 9 in (230 mm) thick, the rear sides were 11.8 in (300 mm) thick, and the roofs were 7 in (180 mm) thick. Sixteen-inch thick armor was the maximum width factories were able to produce at the time of the ships' design; by 1939, however, it was possible to create 18 in-thick plates. These were not installed, because it was estimated that the conversion would delay completion of the ships by 6 to 8 months. The barbettes that held the turrets were also strongly protected. The front portion was 14.7 in (370 mm), the sides increased to 16 in, and the rear portion reduced to 11.5 in (290 mm). The 5 in gun turrets, along with their ammunition magazines, were armored with 1.95 in (50 mm) STS plates.

The side protection system incorporated five compartments divided by torpedo bulkheads and a large anti-torpedo bulge that ran the length of the "armored raft". The outer two compartments, as well as the anti-torpedo bulge, were to be kept empty, while the third and fourth compartments were filled with liquid. The innermost compartment was also to be kept empty. The system was reduced in depth at either ends, by the forward and rear gun turrets. In these areas, the fifth compartment was deleted; instead, there was an outer empty compartment, two liquid-filled spaces, backed by another empty compartment. To compensate for the reduced underwater protection system, these sections received additional armor plating, up to 3.75 in (95 mm) in thickness. The complete system was designed to withstand warheads of up to 700 lb (320 kg) of TNT. Underwater protection was rounded out by a triple bottom that was 5.75 ft (1.75 m) deep. The bottom layer was 3 ft (0.91 m) thick and was kept filled with fluid, while the upper 2.75 in (70 mm) thick layer was kept empty. The triple bottom was also heavily subdivided to prevent catastrophic flooding should the upper layer be penetrated.

Service

North Carolina fitting out.

Construction

Two ships, each costing $50 million, were authorized in January 1937. Their contracts—and construction—were heavily influenced by the legislation of the New Deal; the Vincent-Trammell Act limited company's profit from the ship's construction to 10 percent, while the Walsh-Healey Public Contracts Act specified a minimum wage and required working conditions for workers. In addition, the latter act also greatly affected the ability of the navy to acquire steel: executives in the industry held a dislike for the forty-hour work-week and minimum wage requirements laid out in the Walsh-Healey Act, while two unions—one representing skilled, the other unskilled workers of the steel industry—were currently in conflict. Amid the uncertainty, the navy ran into difficulties trying to buy 18 million pounds of steel for six destroyers and three submarines—much more than would be needed for the new battleships. These problems, combined with labor issues, increased the price of the battleships to $60 million each.

When bids were reviewed, the privately run shipyards' submissions were found to be much higher than that of the government's shipyards, so the contracts were awarded to the New York Naval Shipyard and Philadelphia Naval Shipyard. Heavy lobbying by citizens of Camden and politicians from New Jersey, appealing directly to President Roosevelt, did not result in the construction of North Carolina being moved to New York Shipbuilding.

The ships' construction was slowed by the aforementioned material issues, the changes made to the basic design after this date—namely the substitution of nine 16 in for twelve 14 in—and the need to add both length and strength to the slipways already present in the navy yards. Increased use of welding was proposed as a possible way to reduced weight and bolster the structural design efficiency—for one, it could have reduced the ships' structural weight by 10%—but it was only utilized in about 30% of the ship. The costs associated with welding and an increase in the time of construction made it impractical.

North Carolina

USS North Carolina (BB-55) was laid down on 27 October 1937, the first battleship begun by the United States since the Colorado class of the late 1910s and early 1920s. Although North Carolina was launched on 13 June 1940 and commissioned on 9 April 1941, she did not go on active duty because of acute longitudinal vibrations from her propeller shafts. A problem shared with her sister Washington and some other ships like Atlanta, it was only cured after different propellers were tested aboard North Carolina, including four-bladed and cut-down versions of the original three-bladed. This testing required her to be at sea, and the many resulting trips out of New York Harbor to the Atlantic Ocean caused her to be nicknamed "The Showboat".

After a shakedown cruise in the Caribbean Sea and participation in war exercises, North Carolina transited the Panama Canal en route to the Pacific War. Joining Task Force (TF) 16, the battleship escorted the aircraft carrier Enterprise during the invasions of Guadacanal and Tulagi on 7 August 1942, and continued to accompany the carrier when she moved to be southeast of the Solomons. The Battle of the Eastern Solomons began when Japanese carriers were spotted on 24 August; although American planes were able to strike first by sinking the light carrier Ryūjō, a strike group from a different force, formed around the fleet carriers Shōkaku and Zuikaku, attacked TF 16. In an intense eight-minute battle, North Carolina shot down 7–14 aircraft and was relatively undamaged, though there were seven near-misses and one crewman was killed by strafing. Enterprise took three bomb hits.

I-15's torpedo opened a gaping hole in North Carolina's hull

North Carolina then joined the carrier Saratoga's screen, and protected her while support was rendered to American troops fighting on Guadalcanal. Although she dodged one torpedo on 6 September, she was not able to avoid another on the 15th. The Japanese submarine I-15 fired six torpedoes; three hit the carrier Wasp, one hit O'Brien, one missed, and one struck North Carolina. A 660 lb (300 kg) warhead hit on the port side 20 ft (6.1 m) below the waterline at a point that was just behind the number one turret. It created a 32 x 18 (9.8 x 5.5 m) hole, allowed about 970 long tons (990 t; 1,090 short tons) of water into the ship—which had to be offset with counter-flooding, meaning that another 480 long tons (490 t; 540 short tons) entered—killed five men, and wounded twenty. Although North Carolina could steam at 24 knots (28 mph; 44 km/h) soon after the explosion, she was later forced to slow to 18 knots (21 mph; 33 km/h) to ensure that temporary shoring did not fail. Structural damage beneath the first turret rendered it unable to fire unless in absolute need, and the main search radar failed. As this was the first torpedo to strike a modern American battleship, it elicited a large amount of interest from various officers and bureaus within the navy. It was seen as a vindication by some who believed that too much had been sacrificed in the design of the ships—the torpedo defense system had come close to breaking near one of the most important areas of the ship (a magazine), after all—and the General Board called for the fifth and sixth Iowa-class battleships, Illinois and Kentucky, to have a torpedo bulge added outside of magazines. However, the new Bureau of Ships opposed this on the basis that the system performed how it was supposed to; in any case, no modifications were made.

Repaired and refitted at the facilities in Pearl Harbor, North Carolina operated as a carrier escort for Enterprise and Saratoga for the remainder of 1942 and the majority of 1943 while they provided cover for supply and troop movements in the Solomons. In between, she received advanced fire control and radar gear in March, April and September 1943 at Pearl Harbor in March and April 1943. In November, North Carolina escorted Enterprise while the carrier launched strikes upon Makin, Tarawa and Abemama. On 1–8 December she bombarded Nauru before returning to carrier screening; she accompanied Bunker Hill while that carrier launched attacks on Kavieng and New Ireland.

Joining Task Force 58 in January 1944, North Carolina escorted aircraft carriers as the flagship of Admiral Willis A. Lee for much of the year, providing support for airborne strikes on Kwajalein, Namur, Truk (twice), Saipan, Tinian, Guam, Palau, Woleai, and Hollandia in January–April. Also in April, North Carolina destroyed defensive installations on Ponape before setting course for Pearl Harbor for repairs to a damaged rudder. With repairs completed, the battleship joined with Enterprise on 6 June for assaults within the Marianas; as part of these, North Carolina used her main battery to bombard Saipan and Tanapag.

In late June, North Carolina was one of the American ships which took part in the so-called "Marianas Turkey Shoot", where a majority of attacking Japanese aircraft were shot down out of the air at little cost to the American defenders. Problems with her propeller shafts then caused the battleship to sail to the Puget Sound Navy Yard to receive an overhaul. She returned to active duty in November and to her carrier escort tasks in time to be hit by a typhoon. North Carolina protected carriers while they provided air cover for invasion fleets and launched attacks on Leyte, Luzon, and the Visayas. Surviving another typhoon, one which sank three destroyers, North Carolina continued escort duty when naval aircraft struck Formosa, Indo-China, China, the Ryukyus and Honshu in January and February 1945. During the invasion of Iwo Jima, the battleship provided bombardment support for troops ashore.

Fireworks exploding over North Carolina in 2008, during ceremonies commemorating the commissioning of the submarine North Carolina (SSN-777)

During the assault on Okinawa, North Carolina screened carriers and bombarded targets ashore. Although she was able to shoot down three kamikazes on 6 April, she also was struck by a 5 in (130 mm) shell during that time in a friendly fire incident; three were killed and forty-four injured. The battleship shot down a plane on the 7th and two on the 17th. After receiving another overhaul from 9 May to 28 June, this one in the naval yard at Pearl Harbor, North Carolina operated as both a carrier escort and shore bombardier for the remainder of the war. Of note was a 17 July bombardment of the industrial area in Hitachi, Ibaraki in company with fellow battleships Alabama, Missouri, Wisconsin and HMS King George V, along with smaller warships.

Members of North Carolina's crew and Marine contingent went ashore to assist in occupying Japan. After the official surrender, these men were reembarked in preparation for returning to the United States with troops returning home (Operation Magic Carpet). Passing through the locks of Panama Canal on 8 October, she weighed anchor in Boston on the 17th. After an overhaul in the New York Naval Yard, she participated in exercises before beginning a midshipman training cruise in the Caribbean.

North Carolina was decommissioned in Bayonne, New Jersey on 27 June 1947; she remained in the reserve fleet in until 1 June 1960, when she was struck from the Naval Vessel Register. Instead of the scrapping that faced most of the United States' battleships, North Carolina was sold to the state of North Carolina for $250,000 on 8 August 1961 to be a museum ship. She was dedicated in Wilmington on 29 April 1962 as a memorial to the citizens of the state that died in the Second World War. Listed on the United States' National Register of Historic Places and designated as a National Historic Landmark on 1 January 1986, she remains there today, maintained by the USS North Carolina Battleship Commission.

Washington

The launch of Washington on 1 June 1940

USS Washington (BB-56) was laid down on 14 June 1938, launched on 1 June 1940 and commissioned on 15 May 1941 at the Philadelphia Naval Shipyard. Although commissioned, her engine had not been run at full power—like her sister, Washington had major problems with longitudinal vibrations, which were only tempered after many tests conducted aboard North Carolina. The fixes made it possible to run builder's trials, which Washington did on 3 August 1941; loaded at about 44,400-long-ton (45,100 t; 49,700-short-ton), the propulsion plant was run up to 123,850 shp, and repeated the performance again in February 1942, achieving 127,100 and 121,000 shp.

The battleship was finally able to assume an active role in the war which had just engulfed the United States. Rear Admiral John W. Wilcox chose Washington as the flagship of Task Force 39. On 26 March 1942, Washington, along with Wasp, Wichita, Tuscaloosa and various smaller ships, sailed to bolster the British Home Fleet. During the voyage, Wilcox either fell or was washed overboard into the ocean; he was found soon after face down in the water. It has never been explained how this happened, but there has been speculation that he suffered a heart attack. The force reached the main anchorage of the Home Fleet, Scapa Flow, on 4 April.

Washington and the other ships of TF 39 participated in exercises with the Home Fleet until late April. Along with certain British units, the task force departed the British Isles as TF 99. They escorted some of the Arctic convoys which were carrying vital cargo to the Soviet Union. While carrying out this duty, an accompanying British battleship, HMS King George V, accidentally rammed a destroyer, cutting it in two. Directly behind King George V, Washington passed through the same stretch of sea and received damage from exploding depth charges. Though damage to the hull was minimal—limited to only one leaking fuel tank—many devices onboard the ship were fouled up, including main battery range finders, circuit breakers, three fire-control and the search radars. The American ships then put in at an Icelandic port, Hvalfjörður, until 15 May; they returned to Scapa Flow on 3 June. Washington hosted the commander of naval forces in Europe, Admiral Harold Rainsford Stark, who set up a temporary headquarters on the ship. On 7 June, King George VI of the United Kingdom inspected the battleship.

King George VI of the United Kingdom (left column, walking towards camera) onboard Washington, 7 June 1942. An OS2U Kingfisher is in the background

Washington left the North Sea bound for the United States on 14 July with an escort of four destroyers; upon arrival at the New York Naval Yard on the 23rd, she was given a full overhaul which took a month to be completed. She set sail for the Panama Canal and the Pacific Ocean on 23 August and reached her destination, Tonga Island, on 14 September, where Admiral Willis "Ching" Lee boarded the ship and made her his flagship. Over the coming months, Washington would be focused upon the safe arrival of supply convoys to the men fighting on Guadalcanal. On 13 November, three formations of Japanese ships were discovered, all on course for Guadalcanal. One of the forces was reportedly centered around two battleships. Lee, with Washington, South Dakota, and four destroyers, intercepted the Japanese force on the next night. It was actually composed of the fast battleship Kirishima, the heavy cruisers Atago and Takao, two light cruisers and nine destroyers; they were planning to bombard American troops on Guadalcanal while night gave them protection from aircraft. However, in a furious night battle, the American ships managed to turn the Japanese back, sinking Kirishima and a destroyer, though at the cost of three destroyers sunk and heavy damage to South Dakota. Washington, undetected by the Japanese ships, suffered no damage.

Until April 1943, Washington stayed close to her base in New Caledonia, providing protection for convoys and battle groups that were supporting the Solomons campaign. Returning to Pearl Harbor, she practiced for battle and underwent an overhaul before returning to the combat zone in late July. From August to the end of October, Washington operated out of Efate. She then joined with four battleships and six destroyers as Task Group (TG) 53.2 for exercises; Enterprise, Essex and Independence also participated. TG 52.2 then voyaged to the Gilbert Islands to add additional firepower to the strikes currently hitting them. Departing in late November, Washington steamed to first Makin to provide protection for ships there, then Ocean Island to prepare to bombard Nauru with her sister North Carolina, all four South Dakota-class battleships, and the carriers Bunker Hill and Monterey. All of the capital ships struck before dawn on 8 December; the aircraft carriers struck again soon after. The ships then sailed back to Efate, arriving on 12 December. On Christmas, Washington, North Carolina, and four destroyers left Efate for gunnery practice. By late January, she was made part of TG 50.1 to escort the fast carriers in that group as they launched strikes on Taroa and Kwajalein. She also moved in to hit Kwajalein with her guns on 30 January.

The severe damage done to Washington's bow after her collision with Indiana

Before dawn on 1 February, with the sky still shrouded in darkness, Washington collided with Indiana when the latter left formation to fuel four destroyers. Indiana had radioed that she was going to make a turn to port out of the formation, but soon after starting the turn, her captain ordered a reversal, back to starboard. About seven minutes later, she came into view of lookouts aboard Washington at a range of 1,000 yd (3,000 ft; 910 m). Although crews on both ships frantically tried to avoid the other, it was to no avail; Washington gave Indiana a glancing blow, scraping down a large aft portion of the ship's starboard side. Washingtons fore end was severely damaged, with about 60 ft (18 m) of her bow hanging down and into the water. Ten men, six from Washington, were killed or listed as missing. After temporary reinforcements to the damaged section, she was forced to sail to Pearl Harbor to be fitted with a false bow to make possible a voyage to Puget Sound. Once there, she received a full overhaul, along with a new bow; this work lasted from March until April. Washington did not enter the war zone again until late May.

Washington next participated in the Mariana and Palau Islands campaign, serving again as a carrier escort ship, though she was detached on the 13th to fire on Japanese positions on Saipan and Tinian. With the sortie of a majority of the remaining ships in the Imperial Japanese Navy spotted by American submarines, Washington, along with six other battleships, four heavy cruisers and fourteen destroyers covered the aircraft carriers of TF 58; on the 19th, with the attack of many aircraft, the Battle of the Philippine Sea began. Able to beat off the attacks, Washington refueled and continued escorting carriers until she, with three battleships and escorts, formed a new task group. After a lengthy stop at Enewetak Atoll, she supported troops assaulting Peleliu and Angaur before returning to screening duties. This duty lasted from 10 October to 17 February 1945.

The battleship bombarded Iwo Jima from 19–22 February in support of the invasion there before escorting carriers which sent aircraft raids against Tokyo and targets on the island of Kyūshū. On 24 March and 19 April, Washington bombarded Okinawa; she then departed for Puget Sound to receive a refit, having been in action for the majority of the time since her refit in March–April 1944. This lasted through V-J Day and the subsequent formal ceremony aboard Missouri, so Washington received orders to voyage to Philadelphia, where she arrived on 17 October. Here she was modified to have an additional 145 bunks, so that she could participate in Operation Magic Carpet. Sailing to Southampton with a reduced crew of 84 officers and 835 crew, she brought 185 army officers and 1,479 enlisted men back to the United States; this was the only voyage she would make in support of the operation. The battleship was placed into reserve at Bayonne, New Jersey on 27 June 1947, after only a little more than six years of service. Washington was never reactivated. Struck from the Naval Vessel Register on 1 June 1960—exactly 21 years to the day since her launch—she was sold on 24 May 1961 to be scrapped.

Post-war alterations and proposals

Washington steaming during post-overhaul trials in Puget Sound on 10 September 1945

After the war, North Carolina and Washington remained in active duty for a short period of time, possibly because they were more comfortable and less cramped than the four South Dakotas. The ships received alterations during this period; the Ship Characteristics Board (SCB) directed in June 1946 that four of the quadruple-mounted 40 mm guns be removed, though only two were actually taken off each ship. The 20 mm weapons were also reduced at some point so that both ships were decommissioned with sixteen twin mounts. North Carolina and Washington were decommissioned on 27 June 1947 and subsequently moved to the reserve fleet.

In May 1954, SCB created a class improvement plan for the North Carolina's which included twenty-four 3 in/50 guns directed by six Mark 56s. A month later, the SCB chairman voiced his belief that the North Carolinas and South Dakotas would be excellent additions to task forces—if they could be faster. As such, the Bureau of Ships began to study what it would take to move these ships at 31 knots (36 mph; 57 km/h), four knots faster than their current attainable speed. These proved fruitless due to how much would need to be modified. In order for a North Carolina to obtain 31 knots, 240,000 shaft horsepower (shp) would be required. This, in turn, would necessitate the installation of an extremely large power plant, one which would not fit into the ship even if the third turret was removed. If the outer external belt armor were removed, 216,000 shp would still be required. However, no matter if the belt was taken off or not, the all of the hull form aft would have to be greatly modified to accept larger propellers. The last strike against the project was with its price tag of $40 million—which did not include the cost of activating battleships that had been out of commission for ten years.

Later calculations proved that the North Carolinas could be lightened from 44,377 to around 40,541 long tons (45,406 short tons; 41,192 t), at which 210,000 shp would suffice. At the trial displacement figure of 38,400 long tons (43,000 short tons; 39,000 t), even 186,000 shp would be enough; the 210,000 figure was derived from a 12.5% overestimation to account for a fouled bottom or bad weather. A similar power plant to the one used in the Iowas (generating 212,000 shaft horsepower) would be enough, and if the third turret was removed there would be no problems with weight, but there was not enough space within the North Carolinas. When compared, the current power plant measured 176 × 70 × 24; the Iowa's was 256 × 72 × 26. Lastly, there would be an issue with the propellers; the Iowa class' was 19 ft (5.8 m) wide, while the North Carolina's were 17 ft (5.2 m). In the end, no conversions were undertaken.

Designs for helicopter carriers also contained a plan for a conversion of the North Carolinas. At a cost of $30,790,000, the ships would have been able to embark 28 helicopters, 1,880 troops, 530 long tons (590 short tons; 540 t) of cargo and 200,000 US gal (760,000 L) of oil. All of the 16 in and 5 in guns would have been removed, though the number one turret would have remained so that weights added on the stern half of the ship could be balanced. Instead, the ships would utilize sixteen 3 in guns in twin mounts. Displacement would be lowered slightly, to a fully loaded weight of about 41,930 long tons (46,960 short tons; 42,600 t); speed would not have changed. The ships would have served for about fifteen to twenty years at a cost of about $440,000 a year for maintenance. However, it was estimated that a purpose-built helicopter carrier would be more economical, so the plans were shelved.

Related development

• King George V-class battleship
• Richelieu-class battleship

References

Bibliography

• Friedman, Norman (1985). U.S. Battleships: An Illustrated Design History. Annapolis, Maryland: Naval Institute Press. ISBN 0870217151. OCLC 12214729.
• Garzke, William H.; Dulin, Robert O. (1976). Battleships: United States Battleships in World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0870210998. OCLC 2414211.
• McBride, William H. (1997). "The Unstable Dynamics of a Strategic Technology: Disarmament, Unemployment, and the Interwar Battleship". Technology and Culture. 38 (2). Society for the History of Technology: 386–423. ISSN 0040-165X. OCLC 38122975. JSTOR 3107127. {{cite journal}}: Unknown parameter |month= ignored (help)
• Whitley, M. J. (1998). Battleships of World War Two: An International Encyclopedia. Annapolis, Maryland: Naval Institute Press. ISBN 155750184X. OCLC 40834665.

Web

• DiGiulian, Tony (22 October 2008). "United States of America 16"/45 (40.6 cm) Mark 6". NavWeaps. Retrieved 15 November 2009.
• DiGiulian, Tony (25 January 2009). "United States of America 5"/38 (12.7 cm) Mark 12". NavWeaps. Retrieved 15 November 2009.
• "North Carolina". Dictionary of American Naval Fighting Ships. Navy Department, Naval History and Heritage Command. Retrieved 15 November 2009. {{cite web}}: Unknown parameter |dateformat= ignored (help)
• "North Carolina (BB-55); battleship". Naval Vessel Register. Department of Defense. Retrieved on 15 November 2009.
• "Marshall Islands Campaign, Jan.-Feb. 1944 – USS Washington and USS Indiana Collide, 1 February 1944". Navy Department, Naval History and Heritage Command. 6 October 2006. Retrieved 15 November 2009.
• "Washington". Dictionary of American Naval Fighting Ships. Navy Department, Naval History & Heritage Command. Retrieved 15 November 2009. {{cite web}}: Unknown parameter |dateformat= ignored (help)
• "Washington (BB-56); battleship". Naval Vessel Register. Department of Defense. Retrieved on 15 November 2009.

Primary

• "London Conference of 1936; Treaty for the Limitation of Naval Armament", signed 25 March 1936. Copy available here

External links

• Mohl, Michael. "Post-Dreadnought Battleships". NavSource History. Retrieved 15 November 2009.
• "Top Ten Fighting Ships; North Carolina class battleship". Military Channel. Retrieved 15 November 2009.