graduate

Tone Class, Japanese Heavy Cruisers


Photograph of IJN Chikuma, a Tone-class cruiser, under aerial attack

Naval Historical Center #NH 82404. Cropped by author.


Specifications:


Tonnage 11,215 tons standard displacement
Dimensions 661'1" by 60'8" by 21'2"
201.50m by 18.49m by 6.45m
Maximum speed       35 knots
Complement 850
Aircraft 2 Kure Type 2 Model 5 catapults
5 seaplanes
Armament 4x2 8"/50 guns
4x2 4.7"/45 dual-purpose guns
6x2 25mm AA guns
4x3 Long Lance torpedo tubes
Protection 2073 tons
4" to 0.7" (100mm to 18mm) NVNC and Dücol machinery belt sloped 20 degrees
5.7" to 2.2" (145mm to 55mm) NVNC magazine belt
6.9" to 2.6" (175mm to 67mm) NVNC bulkheads
2.6" to 1.2" (65mm to 31mm) CNC middle deck
2.2" (56mm) lower deck over magazines
3.9"/1.4"/1.2" (100mm/35mm/30mm) steering sides/ends/crown
4.1" (105mm) max uptakes
1" (25mm) NVNC barbette
1" (25mm) NVNC turret
5.1" to 2.6" (130 mm to 70mm) side/1.6" (40mm) overhead conning tower
Lower belt as torpedo holding bulkhead. Torpedo system depth 10'10" (3.3m).
Machinery
4-shaft geared turbine (152,000 shp)
8 Kampon boilers
Bunkerage 2163 tons fuel oil
Range 9000 nautical miles (17,000 km) at 18 knots
Modifications

1943: Light antiaircraft increased to 8x2 25mm guns and Type 21 radar installed.

1944-6: Light antiaircraft increased to 8x3, 6x2, 25x1 25mm guns and Type 13 and two Type 22 radar sets installed.


The Tones were completed in 1938-39 in the Mitsubishi Nagasaki yards. Authorized in 1932, they were to be 8,450-ton cruisers resembling the Mogamis, but dissatisfaction with that design led to a new and quite different kind of ship. The design was also influenced by the Tomozuru Incident, which led to careful consideration of seaworthiness.

The Tones crowded all their main guns onto the forward part of the ship, a measure intended to reduce dispersion of shot. It also freed the rear of the ships for extensive plane handling facilities and resulted in ships that were unusually habitable. They had excellent range and speed and spent most of the early part of the war escorting, and scouting for, the main carrier forces. On the other hand, the unusual turret arrangement yielded an ugly profile and poor firing arcs.

The ships were originally to be partially welded. However, because of concerns about hull strength, Chikuma was almost entirely riveted. The design was originally announced as using 6.1" (155mm) guns, but following the repudiation of the naval disarmament treaties at the end of 1936, the ships were completed with 8" (203mm) guns quickly enough to raise suspicions that the ships had been designed for such guns from the start.

Though designed to carry up to eight seaplanes, it appears that the ships never carried more than five, and this was reduced to four later in the war.


Units in the Pacific:

Tone

Pearl Harbor Attack Force (Nagumo)     

Sunk by aircraft 1945-7-24 at Hashirajima

Chikuma      

Pearl Harbor Attack Force (Nagumo)

Sunk by aircraft 1944-10-25 off Samar


References

CombinedFleet.com (accessed 2007-7-7)

Gogin (2010; accessed 2013-2-14)

Lacroix and Wells (1997)

Prange (1981)
Whitley (1995)

Worth (2001)



Valid HTML 4.01 Transitional