Japanese cruiser Yūbari

Yūbari in 1924
History
Empire of Japan
Name:	Yūbari (夕張)
Namesake:	Yūbari River
Ordered:	October 1921
Builder:	Sasebo Naval Arsenal
Laid down:	5 June 1922
Launched:	5 March 1923
Commissioned:	23 July 1923
Fate:	sunk 28 April 1944 by US submarine Bluegill
General characteristics
Type:	Light cruiser
Displacement:	2,890 t (2,840 long tons) standard (designed); 3,141 t (3,091 long tons) full load (designed); 4,075 t (4,011 long tons) full load (actual)
Length:	138.90 m (455 ft 9 in)
Beam:	12.04 m (39 ft 6 in)
Draft:	3.58 m (11 ft 9 in)
Installed power:	43,060 kW (57,740 hp)
Propulsion:	3 × geared steam turbines 8 × Kanpon boilers 3 × shafts
Speed:	35.5 kn (65.7 km/h; 40.9 mph)
Range:	5,000 nmi (9,300 km; 5,800 mi) at 14 kn (26 km/h; 16 mph)
Complement:	328
Armament:	as built: 6 × 14 cm/50 3rd Year Type naval guns (2×2, 2×1) 1 × 8 cm/40 3rd Year Type naval gun 2 × 7.7mm machine guns 4 × Type 93 torpedoes (2×2) torpedo launchers 8 × 610 mm (24 in) torpedoes 34 × mines 1944: 4 × 14 cm/50 3rd Year Type naval guns (2×2) 1 × 12 cm/45 10th Year Type naval gun 15 × Type 96 25 mm AA guns (6×2, 1×3) 4 × Type 93 torpedoes (2×2) torpedo launchers 8 × 610 mm (24 in) torpedoes 2 × depth charge launchers
Armor:	Belt: 38 mm (1.5 in) Deck: 25 mm (0.98 in) Turrets: 25 mm (0.98 in)

Yūbari (夕張^?) was an experimental light cruiser built between 1922 and 1923 for the Imperial Japanese Navy (IJN). Although a test bed for various new designs and technologies, she was commissioned as a front-line warship and participated in numerous combat operations during World War II before she was sunk by the U.S. Navy. Designs pioneered on Yūbari had a major impact on future Japanese warship designs.

Construction of an experimental light cruiser was authorized under the 1917 8-4 Fleet Program but funding was not available until 1921. By that time, due to restrictions imposed by the Washington Naval Treaty, the Imperial Japanese Navy was forced to adopt a limit in the total displacement of its fleet to 300,000 tons. Yūbari was designed as an experimental scout cruiser that would have the combat potential of the standard 5,000 t (4,900 long tons) Sendai-class cruiser but with a much lighter displacement. Captain Yuzuru Hiraga, Japan’s leading naval architect, assisted by Lieutenant Commander Fujimoto Kikuo, developed an innovative design which strongly influenced the design of Japan’s subsequent heavy cruisers, as well as destroyers.

The basic design premise of Yūbari was that the highest possible speed and weaponry be maintained with the greatest possible weight reduction. To save weight, the armor was integrated directly into the hull structure, forming the side walls and deck. Yūbari had 38 mm (1.50 in) of belt armor protecting the machinery spaces and gun magazines, and 28 mm (1.10 in) armor for the deck and bridge, giving the vessel far superior armor than the previous 5000-ton cruiser designs. The forecastle was given significant flare to improve seakeeping.

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