|Name||No||Yard No||Builder||Laid down||Launched||Comp||Fate|
|利根 [Tone]||600||Mitsubishi, Nagasaki||1.12.1934||21.11.1937||20.11.1938||sunk 24.7.1945|
|筑摩 [Chikuma]||670||Mitsubishi, Nagasaki||1.10.1935||19.3.1938||20.5.1939||sunk 25.10.1944|
|Displacement standard, t||
|Displacement full, t||
190.3 pp 198.8 wl 201.6 oa
|No of shafts||
4 sets Kampon geared steam turbines, 8 Kampon boilers
|Power, h. p.||
|Max speed, kts||
|Armour, mm||belt: 100 (machinery) - 145 (magazines), deck: 65 - 31, turrets: 25|
4 x 2 - 203/50 3-shiki, 4 x 2 - 127/40 89-shiki, 6 x 2 - 25/60 96-shiki, 4 x 3 - 610 TT (24), 6 seaplanes (3 E7K1, 3 E8N1), 2 catapults
Occurrence of these ships, as well as their direct predecessors of Mogami class, was the result of the 1930 London Naval Threaty.
Building of two 8450t cruisers was provided by 2nd Supplementary Programme of 1934. Staff requirement to Tone and Chikuma originally differed from shown to Mogami by only speed decreased on 1kt. However experience of designing of first 155mm cruisers, and also tragedy of overturned torpedo boat Tomozuru and mass newest ships damages during a typhoon have compelled to redesign cruisers. Number of main turrets had shrunk to four, having grouped them in a fore end. Machinery, in comparison with prototype, was displaced in a stern. As result it was possible to shrink a length of an armored belt, to moderate upper weight, to make ship ends lighter, that, in turn, has improved seaworthiness. Exempted aft end allowed to place large air group of six seaplanes.
Already after ships were laid down corrections were made in their design, concerning manufacturing techniques of hulls: they have refused the welding which have not justified in favour of a traditional riveting. Early 1937 when ships still laid on slipways, Naval Staff decided to replace 155mm guns by 203mm, that converted light cruiser to the heavy. As well as on predecessors, such replacement was provided by the design, therefore strengthening of armament has not called necessity of entering of serious corrections for drawings, however building was inhibited, partly because of shortage of 203mm turrets.
Protection scheme of Tone class repeated accepted on Mogami, differing some better protection of magazines: to 145mm of waterline belt abreast and to 55mm of a deck above.
Inner 20°-inclined 110.5m-long main belt protected machinery spaces, connecting with anti-torpedo bulkhead by lower edge. Its height was 2.6m at 77.8m length (or 5.85m with anti-torpedo bulkhead summary). Its thickness was 100mm on upper edge, tapering to 65mm on lower edge, connected with 65mm upper edge of longitudinal bulkhead. Thickness of bulkhead decreased to 34mm near double bottom. Belt was closed by 105-67mm transverse bulkheads. Magazines were protected by narrower belt (4.0m in height summary with longitudinal bulkhead, upper edge of belt was under wl). Its thickness changed from 145mm at upper edge to 55mm near double bottom, this belt also was closed by 175-130mm bulkhead. Main belt was connected with main 31mm deck by 20°-inclined 65mm slopes. Magazines were protected by flat 56mm lower deck. Steering gear compartment was protected by 100mm longitudinal and 35mm transverse bulkheads and 30mm medium deck. Underwater protection consisted of bulges and longitudinal bulkhead, its deep was about 3.3m. Guns had 25mm turrets and 25mm barbettes. CT had 100mm sides and 50mm roof.
1 - 3.1943, both: + 2 x 2 - 25/60 96-shiki, 1-shiki 2-go radar
1/1944, both: - 4 x 2 - 25/60; + 4 x 3 - 25/60 96-shiki, 4 x 1 - 13.2/76
6 - 7.1944, Tone: - 4 x 1 - 13.2/76; + 4 x 3 - 25/60 96-shiki, 25 x 1 - 25/60 96-shiki, 2x 2-shiki 2-go, 3-shiki 1-go radars
6 - 7.1944, Chikuma: - 4 x 1 - 13.2/76; + 4 x 3 - 25/60 96-shiki, 23 x 1 - 25/60 96-shiki, 2x 2-shiki 2-go, 3-shiki 1-go radars
2/1945, Tone: - 7 x 1 - 25/60, 21-go radar; + 4 x 3 - 25/60 96-shiki, 2-shiki 2-go radar (3rd)
Chikuma 26.10.1942 was damaged by American carrier aircraft (up to five bomb hits). 5.11.1943 she was damaged in Rabaul by American carrier aircraft. In battle at Samar 25.10.1944 she was heavy damaged by American carrier aircraft and sunk by destroyer Nowaki. Tone 24.7.1945 was sunk on shallow water off Kure by American carrier aircraft of TF.38. Wreck was additionally damaged 28.7.1945 and abandoned 5.8.1945. She was later salvaged and scrapped in 1947 - 1948.
Many thanks to Wolfgang Stöhr for additional information on this page.