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BB-43 Tennessee Class

The design of the Tennessee class was a considerable improvement over that of earlier U.S. Navy battleships. The two ships featured the same twelve 14"/50 guns and armor protection as in the preceding New Mexico class, and had a similar hull. However, their newly developed four-layer anti-torpedo system, built into the hull sides, and the revised arrangement of boiler and engine rooms permitted by their turbo-electric machinery greatly enhanced their combat survivability.

Tennessee and her sister ship, California (BB-44), were the first American battleships built to a "post-Jutland" hull design. As a result of extensive experimentation and testing, her underwater hull protection was much greater than that of previous battleships; and both her main and secondary batteries had fire-control systems. The Tennessee class, and the three ships of the Colorado-class which followed, were identified by two heavy cage masts supporting large fire-control tops. This feature was to distinguish the "Big Five" from the rest of the battleship force until World War II. Since Tennessee's 14-inch turret guns could be elevated to 30 degrees, rather than to the 15 degrees of earlier battleships, her heavy guns could reach out an additional 10,000 yards. Because battleships were then beginning to carry airplanes to spot long-range gunfire, Tennessee's ability to shoot "over the horizon" had a practical value.

Increased elevation of the main-battery guns and improved gunfire directors atop heavier "cage" masts allowed greater battle ranges. The USS TENNESSEE and USS CALIFORNIA BB-44 were the first US Navy battleships that did not have the casement gun positions mounted in hull, thus giving these ships a much cleaner appearance and reducing wetness forward. All of the five-inch secondary battery guns were now in the superstructure, where they were less vulnerable to heavy seas.

Superdreadnoughts of the California class, displacing 32,000 tons, were declared to represent the high-water mark in the size of American battleships, in a statement presented to Congress, 14 December 1915, by Secretary Daniels outlining the lessons of the European war as to the best type of ship for war. He served warning, however, that a fleet composed exclusively of dreadnoughts must meet defeat at the hands of a better-balanced organization propertly equipped with battle cruisers, scouting craft and submarines.

As a result of the lessons on submarine and torpedo attack, taught by the European war, a new method of construction was employed in the superdreadnought California under construction, at the Mare Island Yard. It is understood that the new torpedo and mine proof construction is gained largely by an improved method of bulkhead building. The bulkheads are of steel, but less rigid than the ordinary type, and resistance is said to have been increased 25 to 30 per cent. A clipper bow, instead of the conventional navy ram, distinguished the California and she had two cage masts bearing fire control platforms. Other characteristics are: Length over all, 624 feet. Depth, 47 feet. Breadth, 95 feet. Mean draft, 30 feet 3 inches. Displacement (at this draught), 32,300 tons. Speed, 2i knots (12 hours). Fuel oil capacity (normal), 1900 tons. Crew, 1022. Twelve 14-inch so-caliber breech-loading rifle. Officers, 58. Twenty-two 5-inch rapid fire guns. Four submerged torpedo tubes. Two i-pounder guns for boats. Four 6-pounder guns for saluting. One 3-inch landing gun. Four 3-inch anti-aircraft guns. Two .30 caliber machine guns. The guns of the main battery will be mounted in threes, in four heavily armored turrets on the ship's center line.

When Battleship No. 44 was assigned to the Mare Island Yard for construction, the name California already had been assigned to No. 40, being built at the New York Navy Yard. The name of the latter was ordered changed to New Mexico, and the California assigned to Mare Island, inasmuch as the California, it was believed, was destined to become the flagship of the Pacific fleet. The flagship was the armored cruiser San Diego, which was called the California until the name was needed by the newly authorized battle ships.

Use of electricity on the California begins with her main engines, driven with motors supplied with current by generators turned by steam turbines of 28,000 horse power. There will be practically no work done on shipboard directly by steam, and the "black gang" of tradition, instead of heaving tons of coal an hour into ever hungry furnaces, will manipulate levers controlling oil burners under the boilers. These latter will be the usual water tube type, but new methods of installation have been devised for practically all the California's engine and boiler room equipment.

To avoid complicated switching connections, induction motors sometimes have two distinct windings, the two windings being connected for a different number of poles. The 7,500-hp., wound-rotor induction motors used to drive the electrically-propelled battleship Tennessee had this type of winding. One winding is connected for 36 poles and the other for 24 poles. In the electrically-propelled battleship New Mexico, the motors were direct-connected to the propeller shafts. The stators can be connected for 24 poles or for 36 poles, giving a speed change of three to two. In wound-rotor types of motors it is necessary to change the rotor as well as the stator connections. Otherwise negative torque will be developed by certain of the rotor conductor belts.

The official trials of the New Mexico showed very successful results and reports of the operation of her machinery satisfactory in every way. The steam consumption per shaft horsepower at different speeds was as follows: 21.08 knots 12.01 Ibs. of steam 19.37 knots 12.33 Ibs. of steam 14.98 knots 12.475 Ibs. of steam 10.26 knots 13.96 lbs. of steam The electrical propulsion equipment of the New Mexico was furnished by the General Electric Co. and that of the Battleship Tennessee was furnished by the Westinghouse Electric & Mfg. Co. The equipment for the Tennessee in general is similar to the New Mexico's, i. e., two turbogenerators operating four a-c. motors direct-connected to the propeller shafts. The motors were a combination design so that with the 24-pole connection the motor is of the wound-rotor type and by means of cross connections it will function as a SB-pole squirrel-cage induction motor. The generators will have a capacity of 10,000 kw. and the motors were each 6700 hp. at 175 r.p.m. on 24 poles and 2125 horsepower at 118.3 r.p.m. on 36 poles, with a 25% overload capacity.

The final trials of the U S S Tennessee, an electrically driven battleship, conclusively proved the advantages of electric drive. The maximum speed attained was 21.38 knots an hour, and from top speed the ship was brought to rest in three minutes. A broadside of twelve 14-inch guns was fired without causing the slightest injury to the electrical equipment. This spoke well for the ability of electrical apparatus to withstand rough treatment. While particular emphasis has been laid on the economy of electric drive, and has been justified, the greatest advantage has been found in the flexibility which is possible in arranging the engine room layout and the ease with which the ship is controlled.

These ships were active units of the inter-war Battle Force. They received modest improvements during the 'Twenties and 'Thirties, among them heavier 5"/25 anti-aircraft guns, the addition of .50 caliber anti-aircraft machineguns and improved gunfire controls. Both were at Pearl Harbor when the Japanese began the Pacific War with their 7 December 1941 surprise attack. Following that disaster, the sunken California was out of the war for over two years, but the relatively lightly-damaged Tennessee was back in service by early 1942.

Both ships received what was probably the most extensive reconstruction given to any of the Navy's wartime major combatants, emerging with much heavier deck armor, a huge improvement in their anti-aircraft battery and modern gun directors. Standard displacement went up some 2500 tons, speed dropped slightly below 21 knots and beam increased to 114 feet, making them too wide to transit the Panama Canal. Their appearance was drastically changed, and now superficially resembled that of the brand-new South Dakota class. Tennessee completed her modernization in May 1943, in time to take part in the Aleutians Campaign. California, which needed extensive repair of her Pearl Harbor damage, was finished in early 1944.

Both ships were heavily engaged in providing bombardment support for amphibious operations through the rest of the war. They were present for the World's final battleship-against-battleship engagement, the Battle of Surigao Strait on 24-25 October 1944, and stayed in action despite receiving "Kamikaze" damage in 1945. Laid up in 1946-47, they were part of the Reserve Fleet until sold for scrapping in 1959, nearly forty years after they were first commissioned.

The Tennessee class numbered two ships, one each built in east coast and west coast Navy yards.

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