Background and description
Right elevation and plan showing the internal layout of the ship
The two Fuji-class ships were the IJN's first battleships, ordered from Britain in response to two new German-built Chinese ironclad warships. At this time, Japan lacked the technology and capability to construct its own battleships and they had to be built abroad. The ships were designed by Philip Watts as smaller versions of the British Royal Sovereign class, although they were slightly faster and had a better type of armour. The ships were 412 feet (125.6 m) long overall and had a beam of 73 feet 6 inches (22.4 m) and a draught of 26 feet 3 inches (8 m) at deep load. They normally displaced 12,230 long tons (12,430 t) and had a crew of 650 officers and ratings. Unlike her sister ship Fuji, Yashima was fitted as an admiral's flagship. The ship was powered by two vertical triple-expansion steam engines, each driving one shaft, using steam generated by ten cylindrical boilers. The engines were rated at 13,500 indicated horsepower (10,100 kW) using forced draught and were designed to reach a top speed of 18.25 knots (34 km/h; 21 mph), though Yashima reached a top speed of 19.5 knots (36.1 km/h; 22.4 mph) from 14,075 ihp (10,496 kW) on her sea trials. The sisters carried enough coal to allow them to steam for 4,000 nautical miles (7,400 km; 4,600 mi) at a speed of 10 knots (19 km/h; 12 mph).[Note 1]
The main battery of the Fuji-class ships consisted of four 12-inch (305 mm) guns mounted in two twin-gun turrets, one each fore and aft of the superstructure. Their secondary armament consisted of ten quick-firing (QF) 6-inch (152 mm) guns, four mounted in casemates on the sides of the hull and six mounted on the upper deck, protected by gun shields. Smaller guns were carried for defence against torpedo boats. These included fourteen QF 3-pounder (47-millimetre (1.9 in)) guns and ten 2.5-pounder Hotchkiss guns of the same calibre, all of which were in single mounts.[Note 2] The ships were also armed with five 18-inch (450 mm) torpedo tubes, one above water in the bow and a submerged pair on each broadside. The Fuji class had a waterline armour belt that consisted of Harvey armour 14–18 inches (356–457 mm) thick. Their gun turrets were protected by 6-inch armour plates and their decks were 2.5 inches (64 mm) thick. In 1901, the ships exchanged 16 of their 47 mm guns for an equal number of QF 12-pounder (3 in (76 mm)) 12 cwt guns.[Note 3] This raised the number of crewmen to 652 and later to 741.