KD2 (I-152) class submersible (1923)

Japan 1925-42: I-152. large oceanic submarines.

The Type KD-2 (伊号第五十二潜水艦, I-go dai-go-jyuni sensuikan) or Kaidai-II (“navy large type”) was the second largest Japanese submarine design, part of a lineage going to the KD-VII or I-76 class, from 1921 to 1943. Albeit two were planned initially, the second, N°64, was re-planned as a KD-IIIa, leaving the sole boat in class, N°51, later renamed I-52 and then I-152. She mostly was used for trials until reconverted as a training submarine, but unlike her near-sister I-51, she saw limited combat experience, attached to the Kure Naval District until 14 July 1942, stricken in August, training hulk at Yamaguchi Prefecture and Hirao until scrapped in 1946.

Development of Project S25

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The Kaichū Type was a post WWI double-hulled medium-sized submarine project of the the IJN. This large oceanic type was to be when planned in 1919 as a “first class” type able to reach Guam or Pearl Harbour from Japan, with a solid surface speed for fleet operations. A lost was inspired by German long-range cruiser submarines used for commerce raiding, of which one was obtained as war reparation, as Japan sided with the entente. This early experience with “U-Kreuzer” usable for battle fleet operation led Japanese strategists to order a long-range reconnaissance boat also able to defend against a fleet approaching Japan.

The KD-2 type followed the KD-1, previously the largest Japanese submarine ever built, ordered as part of 1919 fiscal year. The issue was that having no prior experience in such large designs, and given Japanese ties to UK since the 1902 Anglo-Japanese Alliance, Project S22 (KD-I) partly was inspired by the British K-class submarine, but heavily modified. N°51, was laid down at Kure Naval Arsenal on 6 April 1921 and reached 2,430 tons fully submerged and loaded. It was decided to create a second prototype for the Imperial Japanese Navy as par tof Hachi-Roku Fleet Plan (Eight-six fleet program) in its wake. It seems this came from a rival shipbuilding school of thoughts.

This second prototype, still part of the same Project S22 was confusingly enough named N°51, also laid down at Kure, but a bit later on 14 February 1922. However, construction was suspended and she was eventually decided to have her based instead on the German Type U 139 submarine, mentioned above as a war prize, which made her the Kaidai II type. Thus, this second prototype was designated as Project S25. She was thus revised in plans and laid down a second time on 2 April 1922. Construction proceeded slowly however, as she was launched on 12 June 1923 but completed much later, taking many lessons from I-51, on 20 May 1925, commissionned the same day. The German inspiration led to revise both the powerplant and her hull shape, to reach a better top speed, and thus making her more capable for fleet reconnaissance.

Overall, she was a prototype for a full class at first with the planned N°52-56, ordered but cancelled in 1922 under the terms of Washington Treaty. Herself had to be demoted in 1940 as a training submarine to be kept in conformity with the same treaty and London Conference, freeing submarine tonnage for more modern types. After extensive tests in 1925, now renamed I-51, she was not regarded as a successful design, despite design achievements and slightly superior speed compared to I-51. The cancellation of the class came before formally signing contracts. Another aspect that led to the cancellation aside the treaty was the fact Japan after long negociation with the entente about war prize, ended with seven former Imperial German Navy U-boats that made for the numbers and after years of study, led to design revisions and to the KD-III. I-52 remained the only Kaidai II-type built, like I-51 for the KD-I type. She however enjoyed a longer service, whereas her sister was discarded before the war. Also unlike I-51 she never was designed for, or tested with, a seaplane.

Design of the KD2 class

Hull and general design

Unlike her earlier sister, I-52 as she was renamed under Project S25, was a very different animal, albeit she shared most characteristics with the first prototype of the KD-I type. She was much longer, but for a narrower beam compared to her earlier sister. Standard displacement went from 1,390 tons to 1,500 tons partially loaded (1,524 t) surfaced. Submerged she went from 2,430 tons to 2,500 long tons (2,540 t) fully loaded. The overall length jumped from 91.44 m (300 feet) 100.85 m (330 ft 10 in) but her overall beam (outer hull) went from 8.81 m (29 feet) to 7.64 m (25 ft 1 in) for a better lengh-twidth ratio making the best of her powerplant, and a draft augmented from 4.60 m (15 feet) to 5.14 m (16 ft 10 in).

Design-wise, to get this narrower beam, engineers went from the former double-tube to a single pressure hull, simplifying construction, albeit she was still a bit cramped inside. The outer hull was shaped about the same however, with a continuous deck ending in a raised prow for better seakeeping as well as a straight stem with some flare, and a flat deck with large ballasts either side in a still streamlined look. Her conning tower resembled that of her sister. She also had two main telescopic antennae for her wireless radio in compartments on the port side with axis shaped as extensions that broke her streamlining. She also had “wave deflectors” like spines running close to the CT and aft, which were wave braker/guards for the two antenna when laying down, stored. The deck aft was rather narrow however, and like the short forward deck, covered with wood, whereas the standard color was 1920s IJN medium gray for all surfaces. The symbol “大” was painted in white close to her number on the CT sides.

Like the previous sub, she had retractable diving planes close to her anchors on the bow. The CT, protected by a bulwark platform for the main gun, had a large platform-like extension aft, an enclosed helmsman post with windows, small open bridge and reworked fairwaters around the solid bell containing the two periscopes for watch and attack. It had large loading hatches forward and aft to load torpedoes. Like her earlier sister she also had a surface rudder at her stern. Her crew was rationalized but remained high, from 48 to 58 officers and sailors.

Powerplant

Compared to I-51, I-52 had improved Sulzer diesel engines, for a simpler single hull with ballast blisters, and two engines. I-51 had a double-hull with four-engines but failed to reach her desired speed. These two diesels were more powerful, and that extra output combined with a narrower hull and more streamlined shapes gave her an increased surface speed, but with reduced range. Indeed before trials, I-52 was declared able to reach 22 knots (41 km/h; 25 mph) surfaced, 10 knots (19 km/h; 12 mph) submerged. However in trials she proved disappointing, only clocking 19.5 knots (36.1 km/h; 22.4 mph) surfaced compared to 18.4 knots surfaced for her sister I-51.

Given the compromises made by shifting to a single hull design, oil bunkerage plummitted, from 500 to just 110 tonnes of fuel oil. This was for a 10,000 nautical miles (19,000 km; 12,000 mi), impressive, but still half that of I-51. While underwater, top speed was limited to 10 knots and range at c100 nautical miles at 4 knots economical speed. She could also dive to 60 meters (196 ft), not much given her large size, but more than her near-sister I-51.

Armament

120cm/45 Type 10 deck gun

This 12 cm/45 10th Year Type or 120/45 10-shiki, naval gun was installed. Initially this was a dual purpose anti-aircraft and coastal defense gun, derived from the 12 cm/45 3rd Year Type naval gun. It was relatively simple to produce, threw a powerful shell and did not require external power. It was also used on three cruiser classes and the Taiyō-class escort carrier.

Specs

Mass: 8.5 tons, length 5.94 m (19 ft 6 in), barrel 5.4 m (17 ft 9 in) L/45. 2.16 m (7 ft 1 in) x 2.34 m (7 ft 8 in).
Shell: Fixed QF 120×708mmR 20.6 kg (45 lb 7 oz). Semi-automatic with horizontal sliding-wedge breech, hydro-spring recoil.
Pedestal mount, rate of fire 10-12 rpm, mv 825 m/s (2,710 ft/s) range 16,000 m (17,000 yd).

76cm/40 Type 3 deck gun

According to a few sources (like Conways), I-52 received, ike I-51, a 3-inches Arsmtrong AA gun, licenced in Japan as the Type 3. However it is unclear if it was located in the CT (unlikely) or on the aft deck. 3″/40 (7.62 cm) 3rd Year Type on naweaps. This type was designed in 1914 and built until 1925 as the 8 cm/40 (3″) 3rd Year Type, 8 cm/40 (3″) 11th Year Type and 8 cm/40 (3″) Type 88. It seems that only the Type 88 was used on submarines as it was a “wet gun” present on the RO 33 and RO 35 classes. No mention of any on a KD type, albeit it could have been used later in their training service for submarine gunners.

Type 6 533mm Torpedo

The KD-2 type had six tubes in the bow and reloads for each, plus two in the stern and two reloads, like the previous I-51, for twenty-four of the 6th Year Type torpedo like her near-sister, first type using metric measurements. It was designed at the brand new Imperial Japanese Navy Technical Department, favoring a rule era naming scheme. Development started in 1914, completed in 1917 for a service in 1918 on both surface ships and submarines. Originally defined in the Eight-Eight Program replacing the 18-in by a 21-inch caliber torpedo and planning a 61 cm (24-inch) Type 8. This went with the decision to switch to metric units. In 1922, the Washington Naval Treaty was signed by Japan and forbade any caliber besides 550 mm (French standard) and the international norm remained at 53 cm.

The 1,432 kg (3,157 lb), 6.84 m (22.4 ft) Type 6 was powered by a Wet heater to bring its 203 kg (448 lb) Shimose warhead at 7,650 m (4.13 nmi) at 36 knots (67 km/h) ot 10,000 m (5.4 nmi) at 32 knots (59 km/h), 15,000 m (8.1 nmi) at 26 knots (48 km/h). These were above average performances already compared to other Navies for that caliber. It’s possible they tested the Type 89 in the 1930s, however the latter was only carried by the Junsen and Kaidai-type submarines. They could reach 45 knots. They could also have tested or deployed the Type 92 electric torpedo, leaving no trail (more data on later posts).

Type 3 machine gun

Japan acquired a license and began producing Hotchkiss Mle 1897 machine guns in 6.5mm Arisaka, 87 caliber. During the Russo-Japanese War, each Japanese division had 24 Hotchkiss machine guns. Being lighter than the Russian Maxims, the Hotchkiss performed well. The production evolved to become the Type 3 Heavy Machine Gun in 1914.

Mines

I-52 was supposed to be able to carry sixteen naval mines unlike I-51, of the type compatible with her tubes. This also is not confirmed by all sources. More on Navweaps.

Sensors

These submersibles had a pair of hydrophones, K type echo-sounder and later a K-chubu hydrophone. Other equipments included a ratio transmitter special 4 and 2 receiver RDF-T4. They also had degaussing equipment with three 3/8 inch coils directly below deck and two fitted on the sail like her sister.

⚙ I-51 specifications
Displacement	1,400 long tons surfaced, 2,500 tons submerged
Dimensions	100.85 x 7.64 x 5.14m (330 ft 10 in x 25 ft 1 in x 16 ft 10 in)
Propulsion	2x Sulzer-type No.3 diesels: 6,800 bhp surfaced. 2 EM, 2,000 shp submerged
Speed	21.5 knots surfaced (40 kph), 7.7 knots (14.3 kph) submerged
Range	110 tons fuel, 10,000 nm/10 kts surfaced, 100 nm/4 kts submerged
Armament	8× 533 mm TTs (6 bow, 2 stern, 24), 1x 120 mm/45 deck gun, see notes.
Test depth	60 m (197 ft)
Sensors	K type Hydrophones
Crew	58

Career of the KD2 class

I-52 (1923)

As I-52 in Kure, just commissioned in May-June 1925, colorized by Irootoko Jr. Note her perculiar, reworked clipper bow, pouter hull protrusion and all masts and periscopes up and extended to the full. The wireless radio cables hanging from for the port forward and aft telescopic masts. In the background this is likely IJN Ise or Hyuga. I-52, later I-152, spent most of her career, from 1935 to 1944 in semi-static training.

N°51 was ordered as part of the 1919 naval plan, renamed Project S25, Submarine No.51 (第五十一号潜水艦, Dai-go-jyu-ichi-go sensuikan) at Kure, likely laid down on 2 April 1922, launched on 12 June 1923. She was renumbered I-52 on 1 November 1924, then completed and commissioned the same day after modifications drawn from early experience with I-51, on 20 May 1925. By then and from 1924 she had been under the responsibility of Lt.Cdr (later Rear Admiral) Matsuno Seizo, former CO of HA-9 watching over the fitting our as acting Chief Equipping Officer.
She was from 20 May 1925 attached to the Kure Naval District for initial testing, a short shakedown, fixes, qualifications and more training and in between on 1st December, assigned to Submarine Division 17, part of Submarine Squadron 2, 2nd Fleet (Combined Fleet) under Lt.Cdr Higuchi Shuichiro, former CO of RO-53. So she was intended for operations fropm the start.

On 25 October 1926, while in Hiroshima Bay she was rammed by the Hakata Bay Railway Co. train ferry Fukuoka Maru. Her bow pushed again her port side while manoeuvering, damaging her, fortunately this was at low speed, so damage was light, repaired and possibly paid for by the guilty party, Hakata Bay Railway Company. She was able to participate in the “Special Great Maneuvers” from August to October 1927. She was later under Cdr. (later Captain) Horie Yoshimasa, which took command next 1st December. Just ten days later, he was replaced by Lt.Cdr. Komazawa Katsumi and successively Lt.Cdr Fukuzawa Tsunekichi on 30 Nov. 1929, Lt.Cdr Fukuzawa on 1 April 1930 for additional duty,
LtCdr Shiwa Kunimori from 1 December 1930, Lt.Cdr Kume Ikuji from 16 July 1931, then Lt.Cdr Okushima Takasaburo from 1 November 1932, Lt.Cdr Matsuo Yoshiyasu from 10 April 1933, Lt.Cdr Hamano Motoichi from 1 November 1934.

Then her unit SubDiv 17 (Submarine Division 17) was reassigned directly to the Kure Naval District from 10 December 1928. She was detached however at two occasions to the Kure Defense Squadron, from 30 November 1929 to 1 December 1930 and from 1 October 1932 to 1 January 1933. Reports sent to the IJN staff blamed her poor performances, with unreliable diesel engines, so much so, I-52 never returned to the fleet when SubDiv 17 was reassigned to the Kure Naval District, but she was retained at the Arsenal for crew training in mid-1935, static and berthed. SubDiv 17 was however deactivated for good on 15 November 1935 so she was assigned directly to the Kure Naval District.

I-52 in 1930. From the Japanese book “pictures of warships”, revised edition, published under CC 1899 law by The Navy Association of Japan. She was then painted black (apart for the decks), with her unit number, SubDiv 17, painted on her prow.

She had a succession of commanders and on 20 February 1939 she was commanded by Lt.Cdr Shichiji Tsuneo, then Lt.Cdr Hirokawa Takashi in October 1941. In 1935-41, her records are not clear. It seems there was simply nothing to report as she remained a stationary training ship at the Maizuru Naval Engineering School from the summer of 1935 according to some sources, with others noting she was only assigned there from 15 December 1938. She was perhaps reassigned there at this date, after being assigned already previously, with some sources stating she was assigned there also from 1 February 1939. Bu by the summer of 1941 (31 July) she depended from the Kure Naval District and was still there by December 1941 and afterwards.

With the start of the start of the Pacific campaign, she was under command of Lt.Cdr Sekido Yoshimitsu as additional duty, and at the time of the attack on Hawaii, I-52 was now posted with the Kure Guard Force, same Kure Naval District, and still acting as a training ship. She was moved to the Seto Inland Sea at Kure. About 10 April 1942, she started to test ungamorously various submarine garbage disposal units, notably intended to act as fake destruction decoys. She was then renumbered I-152 or “I-go dai-hyaku-go-jyuni sensuikan” from 20 May 1942 after a reorganization of the submarine force. She changed commanders, from 20 May 1942 Lt.Cdr Shimose Kichiro, from 30 June Lt. Hashimoto Mochitsura and after 14 July when placed in reserve at Kure Lt.Cdr Ota Takeshi. He was her last commanding officer, later killed in action.

I-152 ended in reserve on 14 July 1942, then she was stricken from the navy list on 1 August 1942. But her career did not ended there. Renamed “Haikan No. 14” or “Hulk No. 14”, she was now truly, fully a purely stationary training hulk, permanently anchored and berthed at the submarine school at Kure. She was transferred to the Hirao branch, Ōtake Submarine School, Yamaguchi Prefecture afterwards, and on 15 August 1945, was laid up permanently at Hirao. She was inspected by the allies and later scrapped at the former Kure Naval Arsenal from 1946, and until 1948, at Harima Zosen Dockyard, alongside Ro-13.