The was a group of medium-sized coastal submarines built for the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, Potsdam Declaration, when it was dissolved followin ...

(IJN) during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. The IJN official designation for this class was or . They are also known as Type KS submarine. The type name was shortened to .The read as "Shō" and the read as "Sen-Shō", but the read as "Ko-gata" and the read as "Sen-Shō-gata" in Japanese.

Design and description

In 1940, the IJN designed a

point-defence Point defence (or point defense; see spelling differences) is the defence of a single object or a limited area, e.g. a ship, building or an airfield, now usually against air attacks and guided missiles. Point defence weapons have a smaller range in ...

coastal submarine because they wanted to save their larger submarines for fleet battles. The ''Ro-100'' class was derived from the preceding ''Kaichū'' type. They displaced surfaced and submerged. The submarines were long, had a beam of and a

draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...

of . They had a

double hull A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some di ...

and a diving depth of .Carpenter & Dorr, p. 123 For surface running, the boats were powered by two

diesel engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

s, each driving one

propeller shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power, torque, and rotation, usually used to connect o ...

. When submerged each propeller was driven by a

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

. They could reach on the surface and underwater. On the surface, the ''Ro-100''s had a range of at ; submerged, they had a range of at .Chesneau, p. 204 The boats were armed with four internal bow

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s and carried a total of eight

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

es. They were also armed with two single mounts for Type 96

anti-aircraft gun Anti-aircraft warfare (AAW) is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It encompasses surface-based, subsurface ( submarine-launched), and air-ba ...

s or a single L/40 AA gun.Bagnasco, p. 193

Boats

18 boats were built in 1941-1944 under the Maru Rin Programme (Boat #210-218) and the Maru Kyū Programme (Boat #400-408).

Footnotes

Bibliography

* * * *'', History of Pacific War Vol.17 I-Gō Submarines'',

Gakken is a Japanese publishing company founded in 1947 by Hideto Furuoka, which also produces educational toys. Their annual sales are reported at ¥ 90 billion ($789 million US). Gakken publishes educational books and magazines and produces othe ...

(Japan), January 1998, *''Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces"'', Gakken (Japan), March 2005, *''The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III'', Ushio Shobō (Japan), September 1980, Book code 68343-43 *''The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition"'', Ushio Shobō (Japan), February 1988, Book code 68344-36 {{WWII Japanese ships Submarine classes Submarines of the Imperial Japanese Navy Japan campaign