The were a

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

of two

heavy cruiser A heavy cruiser was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203 mm (8 inches) in calibre, whose design parameters were dictated by the Washington Naval Treat ...

s which saw service with the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, Potsdam Declaration, when it was dissolved followin ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. Both vessels of this class were sunk in 1942 during the

Guadalcanal campaign The Guadalcanal campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by the United States, was an Allies of World War II, Allied offensive against forces of the Empire of Japan in the Solomon Islands during th ...

Design

The ''Furutaka''-class cruisers were the first heavy cruisers in the Imperial Japanese Navy (IJN), also referred to as "A class" cruisers by the IJN. Like the cruiser , their design was the work of Constructor

Captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader or highest rank officer of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police depa ...

Yuzuru Hiraga Vice Admiral Baron was a career naval officer in the Imperial Japanese Navy, Doctor of Engineering and head of the engineering school of Tokyo Imperial University and a leading Japanese naval architect in the 1910s and 1920s, responsible for desi ...

, assisted by Lt. Cmdr. Kikuo Fujimoto. Designed to beat the

U.S. The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous ...

and the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

s, they were as fast as the ''Omaha''s (and nearly 4 knots faster than the ''Hawkins'' class), while firing a heavier broadside, and carrying a larger torpedo battery than either one. Their

flush deck In naval architecture, a flush deck is a Deck (ship), ship deck that is continuous from stem to stern. History Flush decks have been in use since the times of the ancient Egyptians. Greco-Roman Trireme often had a flush deck but may have also ha ...

resulted in both weight savings and increased strength by allowing the hull's longitudinal members to be continuous. As with ''Yūbari'', the design featured side and deck armour integrated into the ship's structure, saving additional weight. Despite the weight-saving efforts, as built ''Kako'' was more than 900 tons heavier than her design weight. As a result, draft was increased by more than 1 metre, subsequently reducing top speed, and the height of the

belt armour Belt armor is a layer of heavy metal armor plated onto or within the outer hulls of warships, typically on battleships, battlecruisers and cruisers, and aircraft carriers. The belt armor is designed to prevent projectiles from penetrating to ...

above the

waterline The waterline is the line where the hull of a ship meets the surface of the water. A waterline can also refer to any line on a ship's hull that is parallel to the water's surface when the ship is afloat in a level trimmed position. Hence, wate ...

. The

porthole A porthole, sometimes called bull's-eye window or bull's-eye, is a generally circular window used on the hull of ships to admit light and air. Though the term is of maritime origin, it is also used to describe round windows on armored vehic ...

s of the lowest-level crew quarters were near enough to the waterline that they needed to be closed when the ships were at sea, reducing ventilation and making the living spaces less habitable. They were the first of the IJN cruisers to feature a substantial

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

, with six distinct levels, providing support for navigation, fire control, communication and command. Due to the high

freeboard In sailing and boating, a vessel's freeboard is the distance from the waterline to the upper deck level, measured at the lowest point of sheer where water can enter the boat or ship. In commercial vessels, the latter criterion measured relativ ...

of these ships, mounting the

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s on the main deck would have caused the torpedoes to enter the water at too steep an angle. Instead, they were mounted on the middle deck in three pairs of fixed tubes on each side. Captain Hiraga argued against this kind of mounting, concerned that during battle either a direct hit or fires could detonate the torpedoes, causing severe damage, as indeed happened with of this class during World War II; additionally, the cruisers , , and , all of which featured similar arrangements, would all be sunk or severely damaged by their own exploding torpedoes.

Modernization

Japanese naval strategists since the early 20th century had planned for a defensive war in the Pacific, with the U.S. Navy as their main opponent. To take advantage of their superior long-range torpedoes, and offset the numerical superiority the U.S. Navy enjoyed, they extensively trained their crews in night torpedo tactics. In 1930, the Naval General Staff, further concerned by the limitations on the size of their navy by the

London Naval Treaty The London Naval Treaty, officially the Treaty for the Limitation and Reduction of Naval Armament, was an agreement between the United Kingdom, Empire of Japan, Japan, French Third Republic, France, Kingdom of Italy, Italy, and the United Stat ...

won approval for an extensive modernization program of the "A class" cruisers. Planned upgrades to the ships included the latest weapons, protection, fire control systems, and communication equipment. From 1931 to 1933 the two ships had their four original anti-aircraft guns replaced by improved 12 cm high-angle electro-hydraulically operated guns, with directors and range finders for them. The original airplane takeoff platform was replaced with a

catapult A catapult is a ballistics, ballistic device used to launch a projectile at a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden rel ...

for a reconnaissance seaplane. They were substantially rebuilt in 1936-1937 (''Kako'') and 1937-1939 (''Furutaka'') as follows:Lacroix & Wells, pp. 251-257 Furutaka on speed trials 1939

The six single Mark I main battery was replaced by three twin-turrets housing the /50-cal Mark I guns from '' Haguro'' and '' Ashigara'' re-bored to Mark II (as there was a shortage of Mark II guns at this timeWhitley, pp. 170). Light anti-aircraft protection was augmented with eight 25 mm automatic cannons in four twin mounts. The six pairs (three per side) of fixed torpedo tubes mounted on the middle deck were replaced with two quadruple mounts using the powerful

Type 93 torpedo The was a -diameter torpedo of the Imperial Japanese Navy (IJN), launched from surface ships. It is commonly referred to as the Long Lance by most modern English-language naval historians, a nickname given to it after the war by Samuel Eliot ...

, located on the upper deck, one on each side of the catapult. The bridge structure was completely rebuilt to accommodate the latest rangefinders and fire control equipment for the main battery, antiaircraft and torpedoes. Platforms were redesigned for aircraft spotters. The twelve original mixed-fuel boilers were replaced by 10 large oil-fired units, along with a redesign of all the boiler rooms, and replacement of coal bunkers with fuel-oil tanks. All of the new equipment resulted in increased electrical power requirements, so three more generators were added to increase power output from 315 kW to 885 kW. These modifications added 560 tons to the ships. To prevent the draft from increasing even more, and to improve stability, bulges were added, simultaneously enhancing antitorpedo protection. As a result, the ships' beam was increased to .

Ships in class

References

Sources

* *

External links

CombinedFleet.com: ''Furutaka''-class Heavy cruisers
{{DEFAULTSORT:Furutaka Class Cruiser Cruiser classes Cruisers of the Imperial Japanese Navy Ships built in Japan