Aoba-class cruiser

Class overview
Aoba soon after completion
Name:	Aoba class
Operators:	Imperial Japanese Navy
Preceded by:	Furutaka class
Succeeded by:	Myōkō class
In commission:	20 September 1927 - 28 July 1945
Completed:	2
Lost:	1
General characteristics (as per Whitley)
Type:	Heavy cruiser
Displacement:	7,100 tons standard; 8,900 tons full load
Length:	185 m (607 ft) (overall)
Beam:	16 m (52 ft)
Draught:	5.8 m (19 ft)
Propulsion:	4-shaft Parsons geared turbines 12 Kampon boilers 102,000 shp (76,000 kW)
Speed:	34 knots (63 km/h)
Range:	6,000 nmi (11,000 km) at 14 kn (26 km/h)
Complement:	625
Armament:	(initial) 6 × 20 cm (7.9 in)/50-cal Mark I guns (3 × 2) 4 × 12 cm (4.7 in)/45-cal (4 × 1) 12 × 61 cm (24 in) torpedo tubes (6 × 2) (final) 6 × 8 in (203 mm)/50-cal Mark II guns (3 × 2) 4 × 12 cm (4.7 in)/45-cal (4 × 1) 8 × 25 mm (4 × 2) machine guns 8 × 61 cm (24 in) Type 93 torpedo tubes (2 × 4)
Armor:	Belt: 76 mm (3 in) Magazine: 51 mm (2 in) Turrets: 25.4 mm (1 in) Conning tower: none Decks: 35 mm (1.4 in) Upper Decks: 48 mm (1.9 in)
Aircraft carried:	(initial) 1, (final) 2
Aviation facilities:	1 catapult

The Aoba-class cruisers (青葉型巡洋艦, Aoba-gata jun'yōkan^?) were a class of two heavy cruisers constructed for the Imperial Japanese Navy (IJN) which saw service during World War II.

The Furutaka class of heavy cruisers (also called “A class” cruisers in the Imperial Japanese Navy) was originally planned to include Aoba and her sister ship Kinugasa. The two ships were laid down in early 1924 with that intent.

In 1924 the IJN Naval General Staff pressured the acting head of the Basic Design Section, Fujimoto Kikuo, to use the newly designed twin 20 cm (8 in) gun turrets on the Furutaka-class ships. Fujimoto agreed to modify Aoba and Kinugasa, but it was already too late to retrofit Furutaka and Kako, which had been laid down in late 1922. The two ships were subsequently renamed as a separate class.

The modifications were significant. The six 20 cm (8 in) semi-turrets, 1 through 6, were replaced by three twin turrets, two fore and one aft. The main superstructure was also modified to accommodate the different fire control requirements of the twin turrets. Other design modifications included using 12 cm (4.7 in)/45-cal HA guns rather than the 7.62 cm (3 in) guns. The airplane takeoff platform, part of which mounted atop the number 4 semi-turret, was replaced with a catapult fitted just fore of the No.3 twin turret. The superstructure aft of the funnels was extensively modified due to the new catapult. The catapults weren't ready before the ships were commissioned. Kinugasa had an compressed-air unit mounted in March 1928, while Aoba had a gunpowder-propelled model mounted in March 1929.

...
Wikipedia