Hatsuharu class destroyer

Nenohi as initially built on full speed trial at Tokyo Bay, 23 August 1933.
Class overview
Name:	Hatsuharu class
Operators:	Imperial Japanese Navy
Preceded by:	Akatsuki class
Succeeded by:	Shiratsuyu class
Subclasses:	Ariake class
Built:	1931–35
In commission:	1933–45
Completed:	6
Lost:	6
General characteristics (as initially completed)
Type:	Destroyer
Displacement:	1,530 t (1,510 long tons)
Length:	109.5 m (359 ft 3 in) overall
Beam:	10 m (32 ft 10 in)
Draught:	3.38 m (11 ft 1 in)
Installed power:	42,000 shp (31,000 kW) 3 water-tube boilers
Propulsion:	2 shafts; 2 Kampon steam turbines
Speed:	36 knots (67 km/h; 41 mph)
Range:	4,000 nmi (7,400 km; 4,600 mi) @ 14 knots (26 km/h; 16 mph)
Complement:	212
Armament:	2 × twin, 1 × single Type 3 127 mm 50 caliber naval guns 2 × single 40 mm AA guns 2 × triple 610 mm (24 in) torpedo tubes 18 × depth charges

The Hatsuharu-class destroyers (初春型駆逐艦, Hatsuharugata kuchikukan) were a class of Imperial Japanese Navy destroyers in the service before and during World War II. The final two vessels in the class, completed after modifications to the design, are sometimes considered a separate "Ariake class".

In compliance with the 1930 London Naval Treaty, the Hatsuharu-class vessels were significantly smaller than the previous Fubuki and Akatsuki-class destroyers. However, Japanese naval designers attempted to stretch contemporary destroyer design to the limit and beyond by equipping the new class with an armament only slightly weaker than that carried by the earlier classes, despite its smaller hull and displacement.

This resulted in a top-heavy design, with severe stability problems, and the weight-control measures used by designers to fit as much armament as possible onto a ship of a given tonnage were carried to an extreme, which further contributed to the structural weaknesses of the ships of this period. This was graphically demonstrated when the torpedo boat Tomozuru capsized in 1934 during heavy seas (the "Tomozuru Incident") and when a typhoon ripped the bows off two Fubuki-class destroyers (the "IJN 4th Fleet Incident") in 1935. As a result of these two incidents the Hatsuharu-class vessels had to be rebuilt (the first two completed had to be rebuilt twice) or modified while building to remedy their stability problems.

The Hatsuharu-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 Japan's naval strategic projections. They were to be armed much as the Fubuki class despite displacing only 1400 tons compared to the 1700 tons of the earlier destroyers. Furthermore, their fire control systems were to be more modern than the older systems and suitable for anti-aircraft use. This required the gun turrets to be modified for high-angle fire, which also meant more powerful motors to traverse and elevate the guns more quickly to engage high-speed aircraft. The torpedo launchers were to be given a protective shield to allow for use in heavy weather and to protect against splinter damage. And the Hatsuharu vessels were to be fitted with modern, enclosed command spaces protected against strafing aircraft. These requirements could only be met by adding weight high up on the ship and increased the ship's center of gravity. The only way to adhere to the allotted displacement was to try to reduce the weight of the hull and other equipment below the waterline as much as possible. But this put the ship's designers in a no-win situation as any reduction of weight below the waterline further raised the ship's center of gravity and reduced her stability.