Profile
of the CA Tone Profile
of the CA Tone 
History: During the 1930's, in a race with the West to build up a powerful navy, the IJN was building ships with extremely heavy armaments compared to their Western counterparts. Although this resulted in unusually powerful warships for their size, one negative consequence is that the ships tended to be top heavy and unstable. After the capsizing of the torpedo boat Tomozuru in a storm in 1934, the construction practice of the IJN was significantly revised.
The IJN cruiser Tone (name after a river in the Kanto plain) and sister ship Chikuma (named after a stream in Nagano Prefecture) were originally designed to be improved Mogami class light cruisers with an improved radius of action (10,000 nm at 18 knots). They were to be equipped with 15-6.1 inch guns mounted in five triple turrets. During their construction in 1936, the Washington Navy Treaties expired and the ships were redesigned with stronger hulls and as heavy cruisers with 8-8 inch guns. Apart from a reduction in weight, the dual 8 inch gun turrets addressed the shot dispersion problems associated with placement of the triple 6.1 inch turrets of the Mogami Class cruisers. To save additional weight, the guns and the associated armor needed to protect their magazine (immediate under the guns) were concentrated forward of the bridge. This compact design also made available additional room in the stern to increase their aircraft carrying capacity as scouting cruisers.
Both Tone and Chikuma were complete by 1938 and took part in a number of engagements. They formed the 8th Cruiser Squadron which consisted of only these two cruisers and operated in company of each other for almost all of their careers. They took part in numerous actions through the Pacific War. Chikuma was sunk in 1944 in the battle of Leyte Gulf. Tone survived to the end of the was and was sunked in 1945 by American aircraft near Kure harbor, Japan. A description of the final moments of the Tone by the U.S. aviator who attacked this ship is now available on the web.
| Displacement | 15,200 tons (full), 11,215 tons (nominal) |
| Dimensions | 620'5" (overall), 649'7" (waterline), 60'8" (beam), 21'3" (draught). |
| Machinery | 4-shaft Kanpon geared turbine with 8 boilers delivering 152,000 SHP |
| Speed | 35 knots. |
| Fuel | 2,163 tons (9,000 miles at 18 knots). |
| Armor | Belt 3.9 inch (around engines), 4.9 inch (around magazine), 1.2-2.5 inch (deck), 1 inch (turrets). |
| Guns |
Main - 8 - 8 in (20 cm) 50 caliber,
No. 2, 3rd Year Type (1914) guns in four twin E3 Type turrets 1938 - 12 - 25 mm guns (6 twin), 4 - 13 mm guns. 1943 - 20 - 25 mm guns (4, triple, 4 twin), 4 - 13 mm guns. 1944 - 57 - 25 mm guns (8 triple, 4 twin, 25 singles). 1945 - 62 - 25 mm guns (12 triple, 4 twin, 18 singles) |
| Gun director |
Surface fire controls - 2 Type 94 Model 2 LA gunnery director with 12 cm binoculars installed in a Type 95 director tower. High-angle fire controls - Type 94 HA directors. Machine gun directors - 3 Type 95 directors. |
| Torpedo | 12 - 24 inch "Long Lance" torpedo tubes in four Type 90 Model 1 triple tube mounts. Twelve reserve torpedoes were carried. |
| Aircraft | 5 aircraft |
| Radar |
Two Type 22 surface search radar. Type 21 air search radar |
| Complement | 850 |