Japanese Battleship Asahi - Design and Description

Design and Description

The design of Asahi was a modified version of the Formidable-class battleships of the Royal Navy with two additional 6-inch (152 mm) guns. The ship had an overall length of 425 feet 3 inches (129.6 m), a beam of 75 feet (22.9 m), and a normal draught of 27 feet 3 inches (8.3 m). She displaced 15,200 long tons (15,400 t) at normal load. The crew numbered about 836 officers and enlisted men.

The ship was powered by two vertical triple-expansion steam engines, each driving one propeller, using steam generated by 25 Belleville boilers. The engines were rated at 15,000 indicated horsepower (11,000 kW), using forced draught, and designed to reach a top speed of 18 knots (33 km/h; 21 mph) although Asahi proved to be slightly faster during her sea trials. The ship reached a top speed of 18.3 knots (33.9 km/h; 21.1 mph) using 15,593 indicated horsepower (11,628 kW). She carried a maximum of 2,000 tonnes (2,000 long tons) of coal which allowed her to steam for 9,000 nautical miles (17,000 km; 10,000 mi) at a speed of 10 knots (19 km/h; 12 mph).

Asahi's main battery consisted of the same four Elswick Ordnance Company 40-calibre twelve-inch guns used in all of the preceding battleships. They were mounted in twin-gun barbettes fore and aft of the superstructure that had armoured hoods to protect the guns and were usually called gun turrets. The hydraulically powered mountings allowed the guns to be loaded at all angles of traverse while they were loaded at a fixed elevation of +13.5°. They fired 850-pound (386 kg) projectiles at a muzzle velocity of 2,400 ft/s (730 m/s).

The ship's secondary armament consisted of fourteen 45-calibre 6-inch (152 mm) quick-firing guns mounted in casemates. Eight of these guns were positioned on the main deck and the other six guns were placed above them in the superstructure. They fired 100-pound (45 kg) shells at a muzzle velocity of 2,300 ft/s (700 m/s). Protection against torpedo boat attacks was provided by twenty QF 12-pounder 12 cwt guns. The 12-pounders fired 3-inch (76 mm), 12.5-pound (5.7 kg) projectiles at a muzzle velocity of 2,359 ft/s (719 m/s). Lighter guns consisted of eight 47-millimetre (1.9 in) three-pounder Hotchkiss guns and eight 47-millimetre 2.5-pounder Hotchkiss guns. The three-pounder gun fired 3.19-pound (1.45 kg) projectiles at a muzzle velocity of 1,927 ft/s (587 m/s) while the 2.5-pounder fired 2.5-pound (1.1 kg) shells at a muzzle velocity of 1,420 ft/s (430 m/s). The ship was also equipped with four submerged 18-inch torpedo tubes, two on each broadside.

The waterline main belt of Asahi consisted of Harvey armour 8.2 feet (2.5 m) high, 5.58 feet (1.7 m) of which was above the waterline at normal load, and had a maximum thickness of 9 inches (229 mm) for the middle 250 feet (76.2 m) of the ship. It was only 4 inches (102 mm) inches thick at the ends of the ship and was surmounted by a six-inch strake of armour that ran between the barbettes. The barbettes were 14 inches (356 mm) thick, but reduced to 10 inches (254 mm) behind the upper armour strake. The armour of the barbette hoods had a maximum thickness of six inches. Diagonal bulkheads connected the barbettes to the side armour, they were 12 inches (305 mm) thick, but only six inches thick at the lower deck level. The frontal armour of the casemates protecting the secondary armament was also six inches thick with the rear protected by 2-inch (51 mm) armour plates. The flat portion of the deck armour was 2.5 inches (64 mm) thick and 4 inches (102 mm) thick where it sloped down to the sides of the ship. The conning tower was protected by 14 inches of armour.

Asahi, like all the other Japanese battleships of the time, was fitted with four Barr & Stroud FA3 coincidence rangefinders that had an effective range of 7,300 metres (8,000 yd). In addition the ships were also fitted with 24-power magnification telescopic gunsights.