Japanese Battleship Mutsu - Reconstruction and Modernization

Reconstruction and Modernization

She underwent major reconstruction at the Yokosuka Navy Yard between 5 September 1934 and 30 September 1936, in which her hull was lengthened to 737 feet (225 m) and anti-torpedo bulges and a triple bottom were added. Horizontal armour was increased over the engine room and magazines and additional armour was also fitted to the faces, sides and tops of her main turrets, the barbette armour was also strengthened. Additions to the fore-mast led to her acquiring the distinctive pagoda mast that became the distinguishing feature of Japanese battleships of her era. She lost her submerged torpedo tubes and two of her upper deck secondary guns. The elevation of her main 16-inch guns was increased from −5 / +30 to −3 / +43 degrees, which increased their maximum range to 33,930 yards (31,030 m) when firing a 2,069 lbs shell. (938.5 kg) HE shell and 42,350 yards (38,720 m) when firing a 2,249 lbs projectile or an (1,020 kg) APC (armour-piercing capped) shell. The elevation of the remaining 5.5-inch guns was increased to 35 degrees. Eight 127 mm dual-purpose guns in four twin mounts and twenty Type 96 25mm anti-aircraft guns in ten twin mounts were added to increase her anti-aircraft protection. A 19.6 metre long Kure Type No. 2 Model 5 catapult and a collapsible crane were fitted forward of "C" turret for three Nakajima E4N2 floatplanes which were to be carried for observation purposes.

All twenty original coal-fired steam boilers were replaced by four new large Kampon and six smaller re-built oil fired units, which developed 92,000 shp, extended the range and allowed her to maintain close to her original speed despite the increased drag of the torpedo bulges and the weight of the additional armour which had increased her standard displacement to 42,785 tons. During trials on 27 July 1936 she attained a speed of 25.283 knots. The changes in her boilers allowed her front funnel to be removed although her rear funnel was enlarged.

The completion of her reconstruction was her last significant modification until 1941 when she was fitted with external degaussing coils and the anti-torpedo bulges were filled with crushing tubes.