Japanese submarine I-152

Japanese submarine I-152 (伊号第五二潜水艦) was the second prototype of the Kaidai-class submarine of the Imperial Japanese Navy, many of which served in World War II.

Background
Following World War I, the Imperial Japanese Navy General Staff began to re-consider submarine warfare as an element of fleet strategy. Before the war, the Japanese Navy regarded submarines as useful only for short-range coastal point defense. However, based on the success of the Imperial German Navy in deployment of long-range cruiser-submarines for commerce raiding Japanese strategists came to realize possibilities for using the weapon for long range reconnaissance, and in a war of attrition against an enemy fleet approaching Japan. . Although a large, long-range Japanese submarine had already been authorized in fiscal 1918 under the Eight-six fleet program as Project S22 (later designated JAPANESE SUBMARINE I-51), a second prototype with a different design was authorized under fiscal 1919.

Design
The first Kaidai prototype, Project S22, was based on the latest Royal Navy design, the British K class submarine; the second Kaidai prototype was based on the German Type U 139 submarine. .This second prototype was designated Project S25

Project S22 was laid down at Kure Naval Arsenal on 2 April 1922, launched on 12 June 1923 and completed on 20 May 1925.

During construction, the vessel was renamed Submarine No.51 (第五一号潜水艦), however, on commissioning into the Imperial Japanese Navy, her name was formally registered as I-52.

With improved Sulzer diesel engines, I-52 was able to use a single hull with two engines, rather than the double-hull, four engine design of the I-51. The greater power and more streamlined shape gave a slightly higher surfaced speed than I-51, or even the SM U135, but with reduced range.

I-52 had a design speed of 22 knots on the surface, and 10 knots submerged, but as completed, achieved 19.5 knots surfaced. Her unrefueled range was 10,000 nautical miles, or only half that of I-51.

Several more of submarines of the same Kaidai II design were planned, but all were cancelled before contracts were even formally signed due to the arrival of seven German U-boats received by Japan as war reparations at the end of World War I.

Operational history
I-52, despite her various technical achievements and superior performance to I-51, was not regarded as a completely successful design. The vessel was never assigned to fleet service, but was retained at Kure Naval Arsenal for crew training and as a test bed for new submarine technologies. She was assigned to Maizuru Naval District for use as a training vessel from 1 February 1939.

With the start of World War II, I-52 was considered obsolete but was retained as a training vessel in the Seto Inland Sea based at Kure. Her designation was officially changed to Japanese submarine I-152 (伊号第五一潜水艦) on 20 May 1942.

I-152 was removed from the navy list on 1 August 1942. Afterwards, she was retained at Kure as a static training hulk for use by the Imperial Japanese Navy Submarine Warfare School, formally designated Hulk #14. After the surrender of Japan, she was scrapped at the former Kure Naval Arsenal from 1946-1948.