Fletcher Class, U.S. Destroyers

National Archive # 19-N-31243

ONI 222

Specifications:

The Fletchers, completed in 1942-45, were the wartime American destroyers. Produced in great numbers, they proved to be a sound design, and became perhaps the most successful of all American destroyer classes. The antiaircraft battery was initially quite weak for a ship of this size, but it was greatly improved as the war progressed. The flush decks gave great structural strength, though at the expense of wet bows. The ships were tough, well-armed, and reliable, with good cruising range. On the other hand, they were not particularly fast for destroyers and lacked somewhat in maneuverability. As designed, they were much less top-heavy than their predecessors, but by war’s end the Navy had dumped enough additional equipment on board to reverse this departure from tradition.

They were the first U.S. destroyers designed after the lapse of the naval disarmament treaties, and the design process took almost two years. The designers originally envisioned relatively small ships, not more than 1600 tons, so that they could be build in greater numbers. The debate over whether torpedoes or guns were to be the primary armament was resolved early in the design process in favor of a balanced armament, and most of the subsequent increase in displacement came from the decision to incorporate Special Treatment Steel (STS) plate as splinter protection around the bridge and machinery spaces. The increase in displacement also meant that a heavier antiaircraft battery could be accommodated, which was just as well, since even this heavier battery proved inadequate and had to be upgraded during the war.

Subdivision was good, with alternating engine and fire rooms for greater machinery dispersion. Construction was all-welded and all decks and the upper hull were of STS, with a thickness of 0.5" (13mm) for the main deck and 0.75" (19mm) for the upper hull. This gave a measure of protection from splinters from near misses. Other portions of the hull and the lower decks were thinner.

The machinery consisted of cruise, high-pressure, and low-pressure turbines, with astern blading incorporated in the low-pressure turbine. The boilers incorporated superheaters and produced steam at 565 psi (3900 kPa) at 850 degrees Fahrenheit (454 degrees Centigrade).

Other improvements to the class included sophisticated radar plotting rooms (ancestors of the modern CIC) and improved antisubmarine gear. The original closed pilot house was replaced in late production units with an open bridge that gave improved all-around vision, which had proven important under air attack. The deck house, as originally designed, was made of lightweight aluminum alloy, but in later units this was replaced by steel due to the shortage of aluminum.

One notable weakness of the class was its poor maneuverability, and it was claimed that even an Iowa-class battleship could out turn a Fletcher. Subsequent destroyer classes adopted twin rudders to improve the turning radius.

The timing of the new design was fortuitous. Friedman (2004) notes that "the 'iron law' of mobilization is that only equipment already in production can pass into mass production, and the design of the Fletcher coincided with the great acceleration of U.S. naval shipbuilding just prior to and early in World War II." Thus the U.S. Navy was poised to mass produce a sound, modern destroyer design for the greatest naval conflict in its history. And mass-produced it was: 175 Fletchers were completed, more than any other destroyer class, and the great majority served exclusively in the Pacific.Construction took place at 11 different shipyards, include Bath-San Francisco, Bath-San Pedro, Bremerton, and Seattle-Tacoma.

Units in the Pacific:

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Detailed plans

References

Adcock (1991)

DANFS

Friedman (2004)

Osborne (2005)

Whitley (1988)

Worth (2001)

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