The were a class of ten 1st Class destroyers of the Imperial Japanese Navy in service before and during World War II, during which all ten were sunk.
Background
The initial six Shiratsuyu-class destroyers were modified versions of the , and had been originally planned as the final six vessels of that class under the ”Circle-One” Naval Expansion Plan.
However, design issues with the Hatsuharu-class ships, notably their “top-heavy” design relative to their small displacement, resulted in extensive modifications, to the point where the final six vessels on order were named as a separate class. The redesign caused the new class to exceed the limitations imposed by the 1930 London Naval Treaty. An additional four vessels were ordered under the ”Circle-Two Naval Expansion Plan of fiscal 1934, and all vessels were completed by 1937. While the process of only giving numbers rather than names has ceased in 1928, these ships also bore the numbers Dai-65 to Dai-74.
As with the Hatsuharu class, the Shiratsuyu-class destroyers were designed to accompany the Japanese main striking force and to conduct both day and night torpedo attacks against the United States Navy as it advanced across the Pacific Ocean, according to Japanese naval strategic projections. Despite being one of the most powerful classes of destroyers in the world at the time of their completion, none survived the Pacific War.
Design
In general layout, the Shiratsuyu-class vessels closely resembled the Ariake sub-class, or final version of the Hatsuharu class, differing only in the lower and more compact bridge design and the shape and inclination of the funnels. The hull retained the general configuration of the Hatsuharu class with a long forecastle with a pronounced flare to improve sea-keeping at high speeds by adding buoyancy and reducing the spray and water coming over the deck, but with a shorter forecastle and longer stern. The same engines were used as on the Hatsuharu class, and due to their greater displacement and draft, the Shiratsuyu-class could only attain 34 knots.
The Shiratsuyu class were the first Japanese warships to be completed with quadruple torpedo mounts and telephone communications to the torpedo station. As with the Hatsuharu class. the torpedo launchers were given a protective shield to allow for use in heavy weather and to protect against splinter damage. The last four vessels (those ordered in 1934) differed slightly from their predecessors and resembled more the succeeding Asashio Class.
Propulsion
The Shiratsuyu class, as with the previous Hatsuharu class, carried two sets of Kampon geared turbines, one for each shaft. Each set consisted one low-pressure and one high-pressure turbine, plus a cruise turbine connected to the high-pressure turbine. The LP and HP turbines were connected to the propeller shaft by a two-pinion reduction gear. Each propeller had a diameter of and a pitch of . The total horsepower of the Shiratsuyu class was only compared to the of their Fubuki-class predecessors, but the machinery was significantly lighter and more powerful on a unit basis. The Shiratsuyus machinery weighed only compared to the of the Fubuki class, or 396 shaft horsepower per tonne versus 347 shaft horsepower per tonne for the older ships.
Similarly the three Kampon Type Ro-Gō boilers used in the Shiratsuyu-class ships weighed in comparison to the boilers used in the Fubuki class, but produced each while the older boilers produced . This gave a ratio of 3.6 kg per shaft horsepower for the Shiratsuyu class compared to the 4.1 kg per shaft horsepower of their predecessors. The newer design of boilers initially used steam pressurized to , just like the older models, but used superheating to improve efficiency while the older boilers simply used saturated steam.
A single 100 kW turbo-generator was fitted behind the reduction gears in a separate compartment and two 40 kW diesel generators were located between the propeller shafts. As initially completed the Shiratsuyu class had a range of at a speed of with of fuel.