Hatsuharu class destroyer
Encyclopedia

The were a class of Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 destroyer
Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...

s in the service before and during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. The final two vessels in the series, completed after modifications to the design, are sometimes considered a separate "Ariake-class".

Background

In compliance with the 1930 London Naval Treaty
London Naval Treaty
The London Naval Treaty was an agreement between the United Kingdom, the Empire of Japan, France, Italy and the United States, signed on April 22, 1930, which regulated submarine warfare and limited naval shipbuilding. Ratifications were exchanged in London on October 27, 1930, and the treaty went...

, the Hatsuharu-class vessels were significantly smaller than the previous and 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
Torpedo boat
A torpedo boat is a relatively small and fast naval vessel designed to carry torpedoes into battle. The first designs rammed enemy ships with explosive spar torpedoes, and later designs launched self-propelled Whitehead torpedoes. They were created to counter battleships and other large, slow and...

  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.

Design

The Hatsuharu-class destroyers were designed to accompany the Japanese main striking force and to conduct both day and night torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 attacks against the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 as it advanced across the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, 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
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 use. This required the gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...

s 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
Strafing
Strafing is the practice of attacking ground targets from low-flying aircraft using aircraft-mounted automatic weapons. This means, that although ground attack using automatic weapons fire is very often accompanied with bombing or rocket fire, the term "strafing" does not specifically include the...

 aircraft. These requirements could only be met by adding weight high up on the ship and increased the ship's center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the 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
Waterline
The term "waterline" generally refers to the line where the hull of a ship meets the water surface. It is also the name of a special marking, also known as the national Load Line or Plimsoll Line, to be positioned amidships, that indicates the draft of the ship and the legal limit to which a ship...

 as much as possible. But this put the ship's designers in a no-win situation
No-win situation
A no-win situation, also called a "lose-lose" situation, is one where a person has choices, but no choice leads to a net gain. For example, if an executioner offers the condemned the choice of dying by being hanged, shot, or poisoned, since all choices lead to death, the condemned is in a no-win...

 as any reduction of weight below the waterline further raised the ship's center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...

 and reduced her stability.
The weight of the hull could generally be reduced by using higher grades of steel that were lighter and smaller for the same strength, reducing dimensions, particularly length, or using advanced construction techniques like welding that saved weight over the conventional riveting. The Japanese used the same high tensile steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 for the Hatsuharu class as they did for the older destroyers and chose not to increase the power of the turbines and boilers to achieve the desired high speed, but lengthened the hull to offset the reduced power of the light-weight machinery. The beam
Beam (nautical)
The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

 was increased to counter some of the extra top-weight, but the draft was reduced to reduce hull resistance, which also reduced stability by lessening the area of the hull beneath the waterline in comparison to the area above it, which was subject to pressure from the wind. Electric welding was extensively used to reduce weight although it was at an early stage of development in Japan and was still problematic.

Extensive weight-saving measures were used during the design and construction of the hull. More frames of lighter construction were spaced more closely together to reduce the thickness of the hull plating and the extensive use of welding (only the longitudinal strength members and a few other parts were riveted) were some of the techniques utilized to reduce hull weight by 66.5 tonne in comparison to the Fubuki class. The Hatsuharu vessels were some 10 metres (32.8 ft) shorter than the Fubuki class vessels, but weighed 4.9 tonne per 1 metres (3.3 ft) of hull length compared to the latter's 5.09 tonne per 1 metres (3.3 ft).

Description

The Hatsuharu-class ships were shorter than their predecessors, at 109.5 m (359.3 ft) overall. The ships had a beam
Beam (nautical)
The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

 of 10 m (32.8 ft) and at full load a draft of 3.35 m (11 ft). Despite the emphasis on weight-saving during construction, the ships were significantly overweight as completed and displaced 1530 metric tons (1,505.8 LT) at standard load, and 1981 metric tons (1,949.7 LT) at full load, nearly 130 metric tons (127.9 LT) more than planned.

The hull of the Hatsuharu class vessels retained the general configuration of the Fubuki-class destroyers with a long forecastle
Forecastle
Forecastle refers to the upper deck of a sailing ship forward of the foremast, or the forward part of a ship with the sailors' living quarters...

 and a pronounced flare of the forecastle to improve sea-keeping at high speeds by adding buoyancy and reducing the spray and water coming over the deck. A large bridge
Bridge (ship)
The bridge of a ship is the room or platform from which the ship can be commanded. When a ship is underway the bridge is manned by an OOW aided usually by an AB acting as lookout...

 structure was located at the aft end of the forecastle deck topped by four fire control stations of various types. Lowest, just above the compass bridge, was the torpedo director (Hassha shikisho), with the gunnery fire direction station (Shageki shikisho) next above. The fire director tower (Hōiban shagekito) was third from the bottom and behind it was the 3 m (9.8 ft) rangefinder. Each of these was protected by 10 mm (0.393700787401575 in) plates of Dücol steel against strafing and shell splinters.

For the first time in a Japanese destroyer a superfiring
Superfire
The idea of superfire is to locate two turrets in a row, one behind the other, but with the second turret located above the one in front so that the second turret could fire over the first...

 turret was fitted forward of the bridge. It was only a single gun Model A turret, to save weight high in the ship, and was mounted on a deckhouse to elevate it above the twin gun Model B Mod 2 (B-gata kai-2) turret mounted on the forecastle deck. The second twin gun turret was mounted at the rear of the ship on the main deck. These turrets were slightly heavier than the earlier Model A and Model B turrets fitted on the Fubukis. All turrets were fitted with the 12.7 cm (5 in) Type 3
12.7 cm/50 Type 3 naval gun
The 12.7 cm/50 Type 3 naval gun was a medium calibre naval gun of the Imperial Japanese Navy used during World War II. It was the standard weapon for Japanese destroyers between 1928 and 1940...

 gun.

The uptakes of the two forward boiler rooms were trunked together aft of the break in the forecastle into the fore funnel while the rear boiler room exhausted into the smaller rear funnel. Both funnels were inclined to the rear to reduce the amount of smoke that might reach the bridge. A tripod mast was fitted between the bridge and the fore funnel. Between the two funnels was the forward 61 centimetres (24 in) triple torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 tube mount fitted on a low platform. Behind it "was a torpedo locker with its mechanical quick reload system (Kiryoku sōtenshiki jihatsu sōten sochi) for the three reserve torpedoes inside." To preserve lateral stability the aft funnel was offset to starboard while the torpedo mount was offset to port. The reload locker was also offset slightly to port and angled inboard to facilitate reloading. The middle torpedo mount was positioned behind the aft funnel on the centerline, but its reload locker was positioned identically to that of the forward mount. Superimposed to starboard and overlapping the middle mount was the rear triple torpedo mount positioned on the rear deckhouse. Immediately behind the mount was its locker positioned on the centerline, but angled slightly to the right so that its mount only had to traverse slightly to align with the locker and begin reloading. This was the first ship in history to be fitted with superimposed torpedo tubes, made necessary by the designer's insistence on fitting nine torpedo tubes despite the Navy's requirement for only six.

A small platform that carried a 2 m (6.6 ft) rangefinder
Rangefinder
A rangefinder is a device that measures distance from the observer to a target, for the purposes of surveying, determining focus in photography, or accurately aiming a weapon. Some devices use active methods to measure ; others measure distance using trigonometry...

 was mounted above the rear torpedo locker and a 90 cm (3 ft) searchlight
Searchlight
A searchlight is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.-Military use:The Royal Navy used...

 was mounted on a tower behind the rear funnel. The two license-built Vickers
Vickers
Vickers was a famous name in British engineering that existed through many companies from 1828 until 1999.-Early history:Vickers was formed in Sheffield as a steel foundry by the miller Edward Vickers and his father-in-law George Naylor in 1828. Naylor was a partner in the foundry Naylor &...

 40 mm (1.6 in) (pom pom) anti-aircraft
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 guns were mounted on an elevated platform at the front of the rear funnel. Curiously they were another case where the designer exceeded the requirements laid down by the Navy.

Propulsion

The Hatsuharu's carried two sets of Kampon geared turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

s, 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
Pinion
A pinion is a round gear used in several applications:*usually the smallest gear in a gear drive train, although in the case of John Blenkinsop's Salamanca, the pinion was rather large...

 reduction gear. Each propellor had a diameter of 3.05 m (10 ft) and a pitch of 3.7 m (12.1 ft). The total horsepower of the Hatsuharu-class was only 42000 hp compared to the 42000 hp of their Fubuki-class predecessors, but the machinery was significantly lighter and more powerful on a unit basis. The Hatsuharu's machinery weighed only 106 tonne compared to the 144 tonne 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 Hatsuharu-class ships weighed 50 tonne in comparison to the 51 tonne boilers used in the Fubuki-class, but produced 14000 hp each while the older boilers produced 12500 hp. This gave a ratio of 3.6 kg per shaft horsepower for the Hatsuharu's compared to the 4.1 kg per shaft horsepower of their predecessors. The newer design of boilers initially used steam pressurized to 20 bars (290.1 psi), just like the older models, but used superheating
Superheating
In physics, superheating is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling...

 to improve efficiency while the older boilers simply used saturated steam
Saturated steam
In thermodynamics, the state of saturation of a fluid indicates that the fluid is at its boiling point temperature. This term can be applied in several ways:*Saturated liquid: fully in the liquid state but is about to vaporize....

.

A single 100 kW turbo-generator was fitted behind the reduction gears in a separate compartment and two 40 kW diesel generator
Diesel generator
A diesel generator is the combination of a diesel engine with an electrical generator to generate electrical energy....

s were located between the propeller shafts. As initially completed the Hatsuharu had a range of 4000 nautical miles (7,408 km) at a speed of 18 knots (35.3 km/h) with 460 tonne of fuel. On trials, had a top speed of 37.64 knots (73.8 km/h) from 47150 hp at a displacement of 1677 tonne.

Armament

The Hatsuharu-class destroyers used the same 50 caliber 12.7 cm gun as the Fubuki-class, but all turrets could elevate to 75° to give the main guns a minimal ability to engage aircraft. During the war the single turret was removed on all surviving ships after 1942. The only anti-aircraft
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 guns were two water-cooled, license-built Vickers 40-millimeter guns. These guns were deemed to be too heavy, slow-firing and short-ranged and were replaced by license-built French Hotchkiss
Hotchkiss et Cie
Société Anonyme des Anciens Etablissements Hotchkiss et Cie was a French arms and car company established by United States engineer Benjamin B. Hotchkiss, who was born in Watertown, Connecticut. He moved to France and set up a factory, first at Viviez near Rodez in 1867, then at Saint-Denis near...

 25 mm (0.984251968503937 in) Type 96 anti-aircraft guns in single, double and triple mounts from 1943 for the surviving ships. Exact numbers are not always known, but was carrying three triple power-driven mounts, including one mounted in lieu of the single 12.7 cm gun turret, one twin power-driven mount fitted on a platform in front of the bridge and two hand-worked single mounts in June 1944. These powered mounts were unsatisfactory because their traverse and elevation speeds were too slow to engage high-speed aircraft and more single mounts were fitted to ships in the last year of the war. For example mounted ten single 25 guns when she was sunk in July 1945. Four license-built Hotchkiss 13.2 mm (0.519685039370079 in) Type 93 machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

s were also fitted to Hatsushimo, but these were of limited utility against modern aircraft.

The 61 cm Type 90 torpedo
61 cm Type 90 torpedo
The 61 cm Type 90 torpedo was a surface-fired torpedo used by the Imperial Japanese Navy during World War II. It was used in the s and in most cruisers, including the , , , and heavy cruisers after refits during the 1930s...

 was mounted in triple tube Type 90 Model 2 launchers, derived from the twin tube Type 89 launcher used in the heavy cruiser
Heavy cruiser
The heavy cruiser was a type of cruiser, a naval warship designed for long range, high speed and an armament of naval guns roughly 203mm calibre . The heavy cruiser can be seen as a lineage of ship design from 1915 until 1945, although the term 'heavy cruiser' only came into formal use in 1930...

s. Shields were fitted to both the torpedo mounts and lockers to protect them from the weather and from strafing aircraft. Initially the shields were made from Duralumin
Duralumin
Duralumin is the trade name of one of the earliest types of age-hardenable aluminium alloys. The main alloying constituents are copper, manganese, and magnesium. A commonly used modern equivalent of this alloy type is AA2024, which contains 4.4% copper, 1.5% magnesium, 0.6% manganese and 93.5%...

 to save weight, but these quickly corroded and had to be replaced. "NiCrMo" steel, taken from the air chambers of obsolete torpedoes, 3 mm (0.118110236220472 in) in thickness, was chosen for the new shields to save weight. The Type 90 Model 2 weighed, including the shield, a total of 14.4 tonne excluding the torpedo itself. Despite the addition of an extra torpedo tube, it was still lighter than the 14.5 tonne of the Type 89. It was traversed by an electro-hydraulic system and could traverse 360° in twenty-five seconds. If the backup manual system was used the time required increased to two minutes. Each tube could be reloaded in twenty-three seconds using the endless wire and winch provided.

Only eighteen depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

s were initially carried in a rack at the stern, but this increased to thirty-six after the autumn of 1942. Apparently no sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 or hydrophone
Hydrophone
A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change...

s were fitted until after the outbreak of the war when the Type 93 sonar and Type 93 hydrophones were mounted. Both of these were inferior to contemporary American and British designs.

Radar

Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 was not installed on the surviving ships of this class until late in the war, possibly as late as 1944. They were given a Type 22 radar on the foremast, a Type 13 on the mainmast and a Type E-27 radar countermeasures
Electronic countermeasures
An electronic countermeasure is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared or lasers. It may be used both offensively and defensively to deny targeting information to an enemy...

 device was carried high on the foremast.

Construction

A dozen Hatsuharu-class destroyers were authorized in 1931 as part of the so-called Circle One Program
1st Naval Armaments Supplement Programme (Japan, 1931)
The , otherwise known as the "Circle One" plan was the first of four expansion plans of the Imperial Japanese Navy between 1930 and the start of World War II.-Background:...

 (Maru Ichi Keikaku). Three were laid down in JFY 1931 and the next three in JFY 1933. The remaining six ships were built as the .
Ships of the Hatsuharu-class
Ship Shipyard Laid down Launched Completed Fate
初春 Sasebo Naval Arsenal
Sasebo Naval Arsenal
was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy. -History:The Sasebo Naval District was established at Sasebo, Nagasaki in 1886, as the third of the naval districts responsible for the defense of the Japanese home islands. After the establishment of the...

14 May 1931 27 February 1932 30 September 1933 Sunk in action, November 13, 1944
子日 Uraga Dock Company
Uraga Dock Company
was a major privately owned shipyard in Uraga, Japan, which built numerous warships for the Imperial Japanese Navy.-History:Uraga Dock Company was founded by Enomoto Takeaki in 1869. A shipyard had already existed in Uraga from the end of the Edo period...

15 December 1931 22 December 1932 30 September 1931 Sunk in action, July 5, 1942
若葉 Sasebo Naval Arsenal 12 December 1931 18 March 1934 31 October 1934 Sunk in action, October 24, 1944
初霜 Uraga Dock Company 31 January 1933 4 November 1933 27 September 1934 Sunk in action, July 30, 1945
有明 Kawasaki Kobe Shipyard
Kawasaki Shipbuilding Corporation
-External links:*...

14 January 1933 23 September 1934 25 March 1935 Sunk in action, July 28, 1943
夕暮 Maizuru Naval Arsenal
Maizuru Naval Arsenal
was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy. -History:The Maizuru Naval District was established at Maizuru, Kyoto in 1889, as the fourth of the naval districts responsible for the defense of the Japanese home islands. After the establishment of the...

9 April 1933 6 May 1934 30 March 1935 Sunk in action, July 20, 1943

Design modifications

On trials the Hatsuharu was found to roll heavily, with a very short period of roll and she heeled at an angle of 38° at high speed when her helm was set to 10°. This demonstrated to the Navy that her metacentric height
Metacentric height
The metacentric height is a measurement of the static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre . A larger metacentric height implies greater stability against overturning...

 was too low. The Navy ordered in September 1933 that 300 millimetres (11.8 in) bulges be fitted on each side to increase her beam and thus raise the metacentric height. Hatsuharu and Nenohi were modified after completion; Wakaba and Hatsushimo were modified during construction. Ariake and Yugure were at a much earlier stage of construction and had their beam increased by 1 metres (3.3 ft). The bulges were estimated to add 30 tonne to the trial displacement.

The capsizing of the torpedo boat in 1934 forced the Navy to re-evaluate the heavy armament of the Hatsuharu and other classes. As a result of the investigations in ship stability after the capsizing of the Tomozuru, all vessels in the Hatsuharu class were modified to improve their stability:
  • The after deckhouse and rangefinder were removed and the forward single 12.7 cm gun mounting was relocated to this position, directly ahead of the after twin gun mount; its magazine was converted for use as a fuel tank.
  • The No.3 triple torpedo mount and its reload locker were removed.
  • The compass bridge was lowered by one level and the anti-strafing armor was removed from the entire bridge structure.
  • Both funnels were shortened by 1–1.5 m (3.3–4.9 ) as were both masts.
  • The forward torpedo tube mount was lowered 300 millimetres (11.8 in), the machine-gun platform by 1.5 metres (4.9 ft) and the searchlight platform by 2 metres (6.6 ft).
  • The bulges were removed and the anchor chain stowage was lowered by one deck.
  • The outer bottom plating was reinforced and about 70 tonne of ballast was added in the ship's bottom.
  • An automatic system was fitted which filled part of the fuel tanks with seawater to compensate for the consumption of fuel and resulting rise in the center of gravity and hence loss of stability. When the sea water was added to the fuel tank due to their different specific gravities the seawater sank to the bottom of the tank, while the oil floated on top.


The first two ships of the class — Hatsuharu and Nenohi — had already entered by the time of the Tomozuru Incident. They were removed from service and modified in the Kure Naval Arsenal
Kure Naval Arsenal
was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy. -History:The Kure Naval District was established at Kure, Hiroshima in 1889, as the second of the naval districts responsible for the defense of the Japanese home islands along with the establishment of the...

. The remaining four members of the class were still under construction and were modified before completion.

Based on the stability issues shown by Hatsuharu during her trials, Ariake and Yugure had been modified for two balanced rudders placed directly behind the propellers and angled outward 18.5° to reduce the angle of heel when turning. These proved to reduce their speed by one knot and were removed after their trials as superfluous since both ships had been rebuilt to reflect the lessons of the Tomozuru Incident.

Reinforcement of the hull

As a result of hull damage sustained by two Fubuki class destroyer
Fubuki class destroyer
The was a class of twenty four destroyers of the Imperial Japanese Navy. The Fubuki class has been called "the world's first modern destroyer." The Fubuki class not only set a new standard for Japanese vessels, but for destroyers around the world...

s during a typhoon on 26 September 1935, the subsequent investigation led to all ships in the Hatsuhuru class spending 3 months in the shipyards having their hulls strengthened, at the cost of an extra 54 tonne of weight, and their fixed ballast increased from 64 tonne. As a result of these and previous modifications the ships were 23.2% heavier, had lost 33% of their torpedo armament and were 3 knots (5.9 km/h) slower compared with their original design values.

Wartime service

All Hatsuharu-class ships were lost during the Pacific War
Pacific War
The Pacific War, also sometimes called the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in East Asia, then called the Far East...

. Four were sunk by aircraft attack, and Nenohi was sunk by the American submarine . Hatsushimo, the last Japanese destroyer sunk during the war, struck a mine while attempting to evade an air attack in July 1945.

External links

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