Ibuki-class cruiser

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For the earlier Ibuki class, see Ibuki-class armored cruiser.

drydock
, 14 March 1947
Class overview
NameIbuki class
Builders
Operators Imperial Japanese Navy
Preceded byTone class
Succeeded byNone
Cost¥60,000,000
Built1942–1945
Planned2
Completed0
Scrapped2
General characteristics (as designed)
TypeHeavy cruiser
Displacement
  • 12,220 
    standard
    )
  • 14,828 t (14,594 long tons) (
    full load
    )
Length200.6 m (658 ft 2 in)
Beam20.2 m (66 ft 3 in)
Draft6.04 m (19 ft 10 in)
Installed power
Propulsion
Speed35 knots (65 km/h; 40 mph)
Range6,300 nmi (11,700 km; 7,200 mi) at 18 knots (33 km/h; 21 mph)
Complement876
Sensors and
processing systems
Armament
  • 5 × 2 - 20 cm (8 in) guns
  • 4 × 2 -
    AA guns
  • 4 × 2 -
    2.5 cm (1 in)
    AA guns
  • 2 × 2 -
    13.2 mm (0.52 in) Type 93 machine guns
  • 4 × 4 - 61 cm (24 in) torpedo tubes
Armor
Aircraft carried3
Aviation facilities2 aircraft catapults

The Ibuki-class (伊吹型, Ibuki-gata) cruisers were the last

launched, but she was in the process of being converted into a light aircraft carrier when construction was suspended in 1945. She was scrapped the following year. The unnamed second ship was scrapped less than a month after being laid down in order to clear her slipway for an aircraft carrier
.

Design and description

The design of the Ibuki class was a minor improvement over the last pair of the Mogami class after those ships had been upgraded during the late 1930s. The main improvement was the replacement of the triple torpedo tube mounts in the older ships with quadruple mounts. They cost 60,000,000

yen each and had a crew of 54 officers and 822 enlisted men.[1]

The ships had a length of 200.6 meters (658 ft 2 in)

full load).[2]

They were fitted with four Kampon geared

kilowatt (400 hp) turbo generators and two 200-kilowatt (270 hp) diesel generators.[3]

Armament

The main armament of the Ibuki class was intended to be ten 50-

13.2 mm Type 93 machine gun mounts were supposed to be mounted on the bridge with 2,000 rounds per gun.[10]

The Ibuki-class ships were intended to be armed with four rotating quadruple 61 cm (24 in) Type 92

centerline, but nothing was done.[13]

Fire control, sensors and aircraft

Two Type 94 fire-control directors, one atop the bridge and the other abaft the funnel, were going to be fitted to control the main guns. They used range data received from three 8-meter (26 ft 3 in) coincidence rangefinders. Two of these were to be installed in turrets Nos. 3 and 4 while the primary rangefinder was mounted above the bridge. A pair of Type 94 high-angle directors, one on each side of the bridge, were intended to control the Type 89 guns. Each director was fitted with a 4.5-meter (14 ft 9 in) rangefinder. The 25 mm guns would have been controlled by two Type 95 directors mounted on the bridge.[14]

Early warning would have been provided by a

mainmast. These would have consisted of one three-seat Aichi E13A and two two-seat Yokosuka E14Y floatplanes. They would have been launched by a pair of Kure Type 2 aircraft catapults, one on each side of the aircraft platform. The ships would have carried a total of 122 powder charges for the catapults as well as four 250-kilogram (550 lb) bombs for the aircraft.[15]

Armor

The ships' armor scheme was only slightly modified from the Mogami-class cruisers. Their

double bottom. It extended from the forward to the rear magazines below the fore and aft turrets and was angled inwards at the top 20° from the vertical to improve its resistance to horizontal shellfire. Over the machinery spaces, it was 100 millimeters (3.9 in) thick at the top and tapered to 30 millimeters (1.2 in) at the bottom. The outer ends of the fore and aft machinery compartments was protected by a 105-millimeter (4.1 in) transverse bulkhead. On the sides of the magazines, the belt was 140 millimeters (5.5 in) thick and tapered to 30 mm at the bottom. The magazines were protected by fore and aft transverse bulkheads 95–140 millimeters (3.7–5.5 in) thick. The steering gear and the rudder compartments had sides that consisted of 100-millimeter (3.9 in) plates and their ends were protected by 50 millimeters (2.0 in) of armor.[4]

The deck above the steering gear and rudders was 30 millimeters (1.2 in) thick. The thickness of the armored deck ranged from 35–40 millimeters (1.4–1.6 in) on the flat and 60 millimeters (2.4 in) on the slope. The sides of the conning tower were 100 millimeters thick while its roof was 50 millimeters (2.0 in) thick. The main gun turrets had 25 millimeters (1.0 in) of armor on all sides and on the roof. The barbette armor ranged from 25 to 100 millimeters (1.0 to 3.9 in) in thickness. The ammunition hoists for the secondary armament were protected by 75 to 100 millimeters (3.0 to 3.9 in) of armor. The funnel uptakes were provided with 70 to 95 millimeters (2.8 to 3.7 in) of armor. There was no separate anti-torpedo bulkhead as that function was performed by the lower extension of the belt armor.[16]

Ships

The two Ibuki-class cruisers were ordered in November 1941 as part of the IJN's

Rapid Naval Armaments Supplement Programme. Both ships were laid down without names, just as Warships No. 300 and No. 301, but the former was named Ibuki on 5 April 1943.[17]

Ibuki-class heavy cruisers
Builder Laid down Launched Notes Fate
Ibuki
Kure[18]
 24 April 1942[18] 21 May 1943[18] Converted to a light aircraft carrier, December 1943[19] Scrapped, 22 September 1946[19]
No. 301 Mitsubishi Shipyard, Nagasaki[18] 1 June 1942[18] Scrapped, 30 June 1942[18]

No. 301 was ordered scrapped less than a month after she was laid down in order to clear her

Sasebo on 21 December. It was originally intended to complete her in March 1945, but this was extended until August. Construction was suspended on 16 March, when the ship was about 80% complete, to allow for the construction of small submarines. Ibuki was scrapped at Sasebo from 22 November 1946 to 1 August 1947.[21]

Notes

  1. ^ Lacroix and Wells, pp. 540–41, 543, 826
  2. ^ Jentschura, Jung and Mickel, p. 87
  3. ^ Lacroix and Wells, pp. 825–26
  4. ^ a b Lacroix and Wells, p. 542
  5. ^ Campbell, pp. 185–86
  6. ^ Lacroix and Wells, p. 543
  7. ^ a b Lacroix and Wells, p. 825
  8. ^ Campbell, pp. 192–93
  9. ^ Campbell, p. 200
  10. ^ Lacroix and Wells, pp. 543–44
  11. ^ Lacroix and Wells, pp. 248, 545
  12. ^ Campbell, p. 207
  13. ^ Lacroix and Wells, p. 545
  14. ^ Lacroix and Wells, pp. 468, 546–47
  15. ^ Lacroix and Wells, pp. 542, 545, 547
  16. ^ Lacroix and Wells, pp. 449, 452, 456, 463, 542
  17. ^ Lacroix and Wells, pp. 539–40
  18. ^ a b c d e f Lacroix and Wells, p. 824
  19. ^ a b Lacroix and Wells, p. 541
  20. ^ Lacroix and Wells, p. 540
  21. ^ Lacroix and Wells, pp. 540–41

References

  • Campbell, John (1985). Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press.
    ISBN 0-87021-459-4
    .
  • Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922-1946. Greenwich: Conway Maritime Press.
    ISBN 0-85177-146-7
    .
  • Jentschura, Hansgeorg; Jung, Dieter; Mickel, Peter (1977). Warships of the Imperial Japanese Navy, 1869–1945. Annapolis: United States Naval Institute.
    ISBN 0-87021-893-X
    .
  • Lacroix, Eric &
    ISBN 0-87021-311-3
    .
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