Nagara Class Cruiser - Design

Design

The Nagara-class was the second class of light cruisers in the Imperial Japanese Navy based a standardized 5,500 ton displacement. In terms of dimensions and performance, it almost identical to the previous Kuma-class cruisers; however, it was the first class of cruisers to be equipped with the new 610 mm Type 93 Long Lance Torpedoes, which required a larger launcher.

The Nagara class used the same hull, engine, and armaments layout as the Kuma class. The Nagara-class hull design was based on a 5,500 ton nominal displacement, with a high freeboard and light bridge structure, behind which was a tripod mast with the fire control platform and two searchlights, the same as the Kuma-class.

The propulsion system for the Nagara-class was based on four axial deceleration turbines with 12 boilers, providing 90,000 hp (67,000 kW). Ten boilers were designed to burn heavy oil, and the remaining two burned a mixture of coal and oil. The Nagara-class vessels were capable of 36 knots (67 km/h), and a range of 9,000 nmi (17,000 km) at 10 kn (12 mph; 19 km/h).

The main battery consisted of seven centerline mounted 14 cm/50 3rd Year Type naval guns in individual gun turrets, (two fore, three after and one on either side of the bridge). The positioning meant that only six of the guns could be brought to bear in a broadside. As with the Kuma-class, the Nagara-class remained highly deficient in anti-aircraft protection, with only two 8 cm/40 3rd Year Type naval guns and two 6.5 mm machine guns. Provision was made for 48 naval mines.

A major difference from the Kuma-class was in the configuration of the bridge, which incorporated an aircraft hangar. Initially, a 33-foot platform was mounted above the No.2 turret, extending over the forward superstructure below the bridge. This was later replaced by an aircraft catapult. Even so, the arrangement proved unwieldy, and the catapult was moved to the rear of each ship, between the No.5 and No.6 turrets during retrofits in 1929-1934. The silhouette of the bridges varied somewhat from ship to ship, as Abukuma has a 20-foot rangefinder located on top of the bridge, whereas Nagara and Isuzu had 15-foot instruments, Natori had a 13-foot, and Yura and Kinu were equipped with 12-foot instruments.