IJN Ha-201 (Type STS)

History

In the middle of the Pacific War, as the Allied noose tightened around the Japanese mainland, there was a growing need to improve coastal defenses against the presence of enemy warships in Japanese waters. The Imperial Japanese Navy apparently missed the opportunity to cause significant disruption to Allied shipping in the Pacific, and the Allies in turn closed most of their land and sea lanes. This created a severe shortage of resources needed to maintain the Japanese war machine in the short term.

After 1943, the struggle increasingly turned to the Japanese mainland, and the defense of the mainland and its coastal waters proved to be a real threat.

The IJN responded by producing ships of the Ha-201 (STS type) class - a group of small fast submarines for operation in coastal waters under the project name Project No. S61. She has a basic form with small external details, including a traditional, highly streamlined tubular fuselage design with curved sides, a flat surface deck, a blunt arrangement and a tapered stern.

Her barrel length was nearly 174 feet. The conning tower is located amidships, while the propeller assembly remains at the extreme aft of the cross rudder assembly. The Ha-201 is specifically designed for speed and whatever offensive firepower it can hold. With a crew of only 22 to 26, she deployed only a pair of 533 mm (21 in) torpedo tubes on the bow.

Power is provided by an underwater electric motor from a conventional arrangement of 400 hp intermediate diesel engine on the water and a 1,250 hp battery powered. Power is transmitted to a single-shaft armature, producing a surface speed of 12 knots and an underwater speed of 14 knots.

The range is up to 3,000 nautical miles on the surface and 105 nautical miles underwater, while still being able to operate from under cover and charge its batteries and oxygen supply. Point defense will only be handled by a single 7.7mm anti-aircraft machine gun, as there are no higher caliber deck guns assigned to the crew.

In all respects, the Ha-201 is in many respects the same class of warships as the German submarine series XXI and XXIII on the other side of the world. The Japanese development was based on data collected during pre-war tests, completed by the "Ship 71" experimental submarine test bed in 1938.

In practice, the Ha-201 class would have tactical utility, but would be more or less operationally limited to a larger scale. Her two torpedo tubes are her full offensive capability (four torpedo reloads in total), which requires the ship to fight in groups and release her "fish" at rather uncomfortable distances to ensure they can find them Target. By this stage of the war, the Allies enjoyed great air and sea superiority, which meant that any Japanese naval vesselwhether merchant or warshipwas a prime target in the air or at sea.

The Ha-201s also received onboard resupply for only 15 days at sea, which severely limited their range before they needed resupply.

Sasebo Naval Arsenal, Mitsubishi Heavy Industries and Kawasaki Shipbuilding have contracted about 79 Ha-201 ships to be built at five naval shipyards, which will be final assembled from prefabricated components built elsewhere to reduce production time. Given the ever-changing nature of the war, especially given Japan's desire for a prolonged conflict, the effort proved quite ambitious. Resources start to be depleted or allocated to other production needs as needed. The daily Allied bombing that proved so effective in Europe also left its mark on the Japanese mainland with the same zeal, destroying many infrastructure and manufacturing targets.

Combining the success of the Allied forces with that of the entire Pacific Rim, hopes for a 90-man Ha-201 fleet were quickly dashed.

In the end, only nine Ha-201 submarines completed what was considered seaworthy, although none of these were sent to sea for operational deployment. At this point, 28 more keels were laid, but by the time Japan surrendered on August 15, 1945, these were only half-finished products.

Existing examples were subsequently captured and evaluated by the Americans, and some technological advances were incorporated into the new generation of U.S. Navy submarines (as well as technology from Europe evaluating German submarines).

A Ha-201 class submarine was completed "post-war" on 16 August 1945, bringing the ready Ha-201 crew to 10 men. All were decommissioned and decommissioned, scrapped or sunk by 1950. The Ha-201 submarine has been tested at an operating depth of 330 feet.

Specification

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