The IJN school cruisers

The three Katori class light cruisers, Katori, Kashima and Kashii had been designed as training cruisers in peacetime, that could take on in wartime the role of destroyers and submarine leaders.

Design-wise they were short but beamy, slow and under-armed, regarded in general of low military value. Nevertheless in 1941 they came into first line service, engaged in combat with a revised AA, including three twin 76 mm mounts, and 25 x 25 mm AA, while their torpedo tubes were landed. This AA artillery was further increased and the catapult dismounted. In Combat, IJN Katori was damaged near Truk, finished off by US Navy aircraft in April 1944, Kashii torpedoed and sunk by an Avenger in the China Sea (January 1945), but Kashima survived the war in home waters, eventually broken up in 1947.

Design development of the Katori class ()

The Katori-gata renshū-jun'yōkan (香取型練習巡洋艦) or Katori class training cruisers originally came from the Imperial Japanese Navy (IJN) need to have dedicated, modern training ships in the FY1937 and FY1939 Supplementary Naval budgets. The Pacific War saw them used as administrative flagships for several fleets, submarine command and control vessels and and command escort squadrons. Emphasis in the design was put on accomodation and versatility rather than ofenssive capabilities. They were upgraded as the war progressed, but their core design was certainly not favoring first-line duties.

In 1935, the IJN had no shortage of potential training ships. With the Washington treaty, some vessels had been relegated to training roles: IJN Yodo (1907), Yahagi, Hirado, all discarded in 1940 were used for subsidiary duties and mobilizable as training ships, the aicraft carrier Hosho was basically used also as training carrier in 1940. The largest capital ship still on duty was the IJN Settsu, since 1924 used as a disarmed target ship, and used for training aviators in 1940 also.

The main TS of the IJN were in fact former armoured cruisers, the four Asama class (1899), IJN Yakumo (1899), Adzuma (1899), and the Kasuga class (1902). But indeed, there was no purpose-built modern training ship in service with the IJN.



In 1936 it was felt the ageing cruisers needed replacement, and that three modern training ships could replace at least the Asama class vessels. A basic design was studied that year, based on sepcifications, then the lead ship was ordered in the 1937 Supplementary Naval budget. These purpose-designed ships were specifically to train officers (cadets) differed from regular cruisers in many aspects. Cost-issues forced a construction to commercial standards (something familiar to us today).

Armament was kept minimal and in fact comprised a destroyer-grade main armament, easier to manage, the minimum of torpedo tubes for training (twin banks) and samples of secondary and tertiary artillery. Emphasis was placed instead on facilities, for command & control. Not only they had pkenty of internal space to accomodate many cadets, their instructors, but also all the necessary amenities to a command staff, in addition to the regular ship's staff, the captain, officers, and men required to run the ship. This imposed a vessel not tailored for speed but clearly to house a very large crew and act as a mobile base.

Detailed Design, as built

One most striking aspect of these were their high freeboard and compact size. They were beamy, at 1/7 ratio, for greater initial stability. It was ideal not to have trainees unfamiliar with lives at sea not sick for weeks. Katori were the only IJN cruisers with a mixed plant, with steam turbine alongside diesel propulsion, mated on the same two shafts. They were intended to maximize the ships' instructional value also for the machinery size, while still procuring a better range than usual, rather than speed. they had a combined output of 6,000 kW (8,000 shp) capping them to 18 knots (33 km/h), way too slow for cruiser duties, but more for shore patrols or gunboat duties.

Construction

Src wargaming forums. They displaced 5,890 long tons (5,985 t) normal and 6,180 long tons (6,279 t) fully loaded, for a length of 129.77 m (425 ft 9 in), a beam of 15.95 m (52 ft 4 in) and draught of 5.75 m (18 ft 10 in). A fourth ship was planned, Kashihara (橿原) ordered to Mitsubishi at Yokohama. Laid down on 23 August 1941, construction was stopped on 6 November 1941, and she was later scrapped.

Powerplant

Two shaft geared turbines plus diesel motors for extra range, 3 Kampon boilers 8,000 shp (6,000 kW), top speed 18 knots (21 mph; 33 km/h), Range 9,000 nautical miles (17,000 km) at 10 knots (19 km/h)

Protection

Gun turrets: 10 mm (0 in), Conning tower: 10 mm (0 in)

Armament

The main armament of each ship was the same type used on the light cruiser Yūbari, in "A" and "Y" positions. There was just a pair of 127 mm (5 in) AA guns in "X" position and two pairs of 25 mm AA guns, two pairs of torpedo tubes, 533 mm (21.0 in) Type 96 torpedoes. Four 140 mm (5.5 in)/50 cal. guns in twin turrets, twin 127 mm (5 in)/40 cal. AA guns, four Type 96 AA guns (later increased to 30), eight single 13.2 mm (0.52 in) AA guns, two twin 533 mm (21 in) torpedo tubes. They carried four single 50 mm saluting guns. They also had a catapult mounted amidships, and single Aichi floatplane, but no hangar.

Construction

The name of the Kashii was taken from "Kashii-Gu", one of the Shinto shrine for Emperor Chūai and Emperres Jingū (mythological) on Fukuoka city.
Author's HD profile illustration, IJN Katori as built

Specifications

Displacement 5,890 t. standard -6 500 t. Full Load
Dimensions 129.77 m long, 15.96 m wide, 5.75 m draft
Propulsion 2 propellers, 2 turbines, diesel engines, 3 boilers, 80,000 hp.
Top speed 18 knots
Armor Belt 50 mm
Armament 4 x 140 (2 × 2), 1 × 2 76 mm, 4 x 25 mm AA, 4 x 533 mm (2 × 2) TTs, 1 floatplane
Crew 160 + 200 students

Resources

Links

on shipmodels.info
on navypedia
Katori on combinedfleet.org
Kahima on combinedfleet.org
The Katori clas (general) on combinedfleet.org


Wikimedia commons open source photos

Books

Editorial department of magazine "Maru" (1990) "THE IMPERIAL JAPANESE NAVY vol9 Light Cruisers II / Gunboats" Kojin-sha publishers pp.161-181
The Society of Naval Architects of Japan (1975) "Plans of ships of the Imperial Japanese Navy, History of shipbuilding in Showa era separated volume", published by Hara-shobo, p. 65
Fukui Shizuo " Current status survey of machine gun, radar, IFF etc on each vessels, from ""Blueprints about placement of additions of weapons after operation A-Go"" ", Ushio shobo Kojinsha
Janes's 1940
Conway's all the world's fighting ship 1922-47

Modeller's corner

On scalemates

The Katori class in action

IJN Katori

Built by Mitsubishi at Yokohama shipyard. Commissioned 20 April 1940. Assigned to the Sixth Fleet, based at Kwajalein. On 1 February 1942, was attacked by torpedo-bombers from USS Enterprise, and sustained damage. Repaired at Yokosuka. During the American attack on Truk on 17–18 February 1944, was attacked by aircraft and hit by a torpedo. Several hours later was attacked again, and sunk by 16-inch (406mm) shells from USS Iowa (BB-61). No survivors were recovered. Struck from the Navy List 31 March 1944.

IJN Kashii

Built by Mitsubishi at Yokohama. Commissioned 31 May 1940. From December 1941, flagship of the Fourth Fleet based at Truk. In 1942 covered the landings at Rabaul and Kavieng, Tulagi and Port Moresby, Rabaul, and New Guinea. In late 1943 reassigned to the Kure Training Division. In dry-dock from November 1943 until January 1944. Served as a transport ship, and modified for the anti-submarine role in late 1944. Struck from the Navy List on 5 October 1945. After the war used as a repatriation transport. Scrapped 1947.

IJN Kashima

Built by Mitsubishi at Yokohama. Commissioned 15 July 1941. Assigned to the Southern Expeditionary Fleet in 1941. In 1942 participated in the invasion of North Sumatra and Burma. In 1943 made transport runs carrying troops and supplies. In 1944 modified for anti-submarine warfare. On 12 January 1945, was attacked by US aircraft, was hit by a torpedo, then two bombs, and sank. Only 19 of 621 aboard were saved.

Naval History