South Dakota Class, U.S. Battleships

Naval Historical Center #97263

ONI 222

Specifications:

The South Dakota class was designed before North Carolina was even completed.  With war clouds gathering, it was felt that work on the two battleships for fiscal year 1938 should be started at once, even if this meant there would not be time to absorb all the lessons of the FY1937 ships.  Under the Deficiency Authorization of 25 June 1938, Congress approved another pair of 35,000 ton battleships, which resulted in four South Dakotas being built.  By that time, the Iowas were already under design, but Congress specified the actual size of the ships, ruling out another pair of Iowas.

The redesign stemmed from the belief that the North Carolina design made too many compromises.  The new design carried the same main armament, but with increased protection, especially against shells following an underwater trajectory (which had been studied too late to affect the North Carolina design, other than adding simple patches over the magazines). Another issue was that the North Carolinas did not have the space to serve as fleet flagships, so the South Dakota was designed to be a fleet flagship (which is why she had two fewer twin 5"/38 turrets than her sisters).  The other three ships of the class included division flag quarters, like the North Carolinas.

Unlike the North Carolinas, whose main armor belt was the outer surface of the ship, the South Dakotas had their main armor belt included within the hull.  This allowed for a more compact hull design. The initial concept of having a knuckle in the armor, with the top half of the belt angled in toward the ship and the bottom half also angled in toward the ship, was dropped due to weight considerations.  The tapering bottom of the armor belt was included in the torpedo protection scheme, and it was hoped that this would improve the efficiency of the system against both underwater explosions and shells following an underwater trajectory.  Unfortunately, this was not tested on a caisson until after the four ships were well along, and it turned out that this new scheme was less effective than the North Carolina design.  The design of the Iowas was also too far along and the Iowas carried the weaker torpedo protection scheme.  The Montana class would have returned to the better torpedo protection carried by the North Carolina class.

A unique feature of this class was the "tunnel" formed between the two skegs for the outboard propellers.  In order to achieve the desired speed, the cross section of the hull had to decrease, but this could not be accommodated in the beams because of the location of the magazines. Instead, the required decrease in cross section was taken from below the hull, resulting in the tunnel.  This arrangement caused less problems with vibration than in the North Carolinas, but the Navy continued to experiment throughout the war with different propeller configurations to reduce vibration.

A redesigned machinery plant boosted shaft horsepower to 130,000, allowing the South Dakotas to match the speed of the North Carolinas on a shorter hull.  Temperature and pressure were the same as the North Carolinas, 565 psi / 850 degrees F.

The main battery was three triple 16"/45 turrets, the same as on the North Carolina.  While South Dakota had only eight twin 5"/38 guns, the other three ships of the class had ten twin 5"/38.  As designed, the light antiaircraft weapons were three or four quadruple 1.1" guns, but these were quickly replaced with a forest of 20mm Oerlikon and 40mm Bofors guns.

These ships were an interesting contrast with the Yamato class.  With one of the most efficient armor schemes ever applied to a capital ship, and a solid main battery, the four South Dakotas might well have been victorious in a gun duel with the two Yamatos — a roughly equivalent weight match up. 

South Dakota herself was an unlucky ship.  Referred to as "Sodak" or "Battleship X" based on Naval press releases, her crew called her "Big Bastard."  Before seeing action, she grounded on coral at Tongatabu on 21 August 1942.  After being repaired, she provided antiaircraft defense for Enterprise, shooting down 26 attackers and suffering two hits and a near miss.  One bomb hit turret #1, doing little damage to the turret but injuring the captain and 49 other men, one of whom later perished.  The hit also damaged two 16" guns of turret #2 badly enough they were not used in the Naval Battle of Guadalcanal. One of these failed when subsequently tested at the proving grounds.

On the night of 26-27 October 1942, South Dakota collided with destroyer Mahan while trying to avoid a submarine contact.  At the Naval Battle of Guadalcanal, her electrical system shorted out at a crucial moment and the ship blundered into the Japanese line.  Her toughness, and poor Japanese shooting, allowed her to survive, but her unarmored upper works were completely shattered.  The decision to maintain ship control, fire control and flag plot in the heavy conning tower was wise as these suffered little damage.  While she was rendered unable to fight an effective night action, the ship's buoyancy was not affected, and she was able to retire independently.  The Massachusetts experienced a similar occurrence with her electrical system off North Africa, leading to changes in the electrical switchboards aboard all ten new battleships.

South Dakota was hit by a bomb at the Battle of the Philippine Sea that destroyed the captain's and admiral's quarters, and she was saved from destruction in a magazine explosion the next year only by the quick actions of her captain (the legendary "Swede" Momsen, a submarine expert destined for flag rank who was serving his obligatory tour in command of a major surface unit) and her damage control personnel.

Indiana replaced South Dakota on the battle line after South Dakota was damaged in the Naval Battle of Guadalcanal.  Her only serious damage was suffered when she turned out of formation at night and was rammed by Washington.  A torpedo bomber attacked Indiana during the Battle of the Philippine Sea, but gunfire destroyed both the plane and the torpedo moments after it was released.  A kamikaze managed to crash into the side of her hull, but inflicted no damage worse than a dent, though flying debris injured five men.  Indiana was present for the surrender in Tokyo Bay.

Massachusetts first saw action in the Atlantic, where she shelled Casablanca Harbor and the French battleship Jean Bart.  She served in the Pacific for the remainder of the war, providing escort for carrier forces. Massachusetts survived the war, evaded the scrap pile, and is now a museum ship in Massachusetts State.

Alabama first served with the British Home Fleet, then moved to the Pacific.  While screening a carrier task force during the evening of 21-22 February 1944, the aftermost 5" mount, number 59, fired into the rear of the amidships 5" mount, number 55.  One round detonated within the gun mount, killing five and injuring 11.  The Board of Inquiry found that part of the mechanism of the firing cut-out system was exposed and could be inadvertently hit, and a metal cover was installed to prevent a repeat occurrence.  After the war,  Alabama was turned into a war memorial in Mobile, Alabama.

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References

DANFS
Dullin and Garzke (1976)
Friedman (1985)

Gogin (2010)

Maas (1999)

Worth (2001)

The Pacific War Online Encyclopedia © 2007, 2009, 2013 by Kent G. Budge and John E. Kollar.  Index

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