The submarines were double-hulled medium sized submarines of the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. They were derived from the .

Several variants existed. From 1934 to 1944, the K6 type (Ro-33 Class) and the K7 type (Senchū, Ro-35 Class) were built. They were equipped with a 3.0 inch (76.2 mm) gun and four 53 cm torpedo tubes for ten Type 95 Long Lance torpedoes.

Most of these submarines were destroyed in combat, suffering from Allied anti-submarine warfare

Anti-submarine warfare

Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....

 measures, and only the Ro-50 survived the war.

Kaichū I (Ro-11 class)

Project number S7. In 1910s, the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 (IJN) bought a license of Schneider

Schneider Electric

Schneider Electric is a French global company. It was founded in 1836 by two brothers, Eugène and Adolphe Schneider.In the first part of the 20th century, Schneider et Cie associated itself with Westinghouse Systems, a major international electrical group at the time. The group began manufacturing...

-Laubeuf design submarine. The IJN used the design as model and built the S Type (Schneider Type) submarine, the Ha-9 and Ha-10. The Kaichū I is the submarine which jumboized the S Type submarines.

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Fate
  No.19 Submarine the same shall apply hereinafter	Kure Naval Arsenal Kure Naval Arsenal was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy. -History:The Kure Naval District was established at Kure, Hiroshima in 1889, as the second of the naval districts responsible for the defense of the Japanese home islands along with the establishment of the...	25-04-1917	25-10-1917	31-07-1919	Renamed Ro-11 01-11-1924. Decommissioned 01-04-1932.
  No.20 Submarine Ro-12	Kure Naval Arsenal	25-04-1917	01-12-1917	18-09-1919	Renamed Ro-12 01-11-1924. Decommissioned 01-04-1932.

Kaichū II (Ro-13 class)

Project number S18. The Kaichū II had an increased range compared with the Kaichū I, and the turning torpedo tubes were removed.

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Fate
  No.23 Submarine Ro-13	Kure Naval Arsenal	14-09-1918	26-08-1919	30-09-1920	Renamed Ro-13 01-11-1924. Decommissioned 01-04-1932.
  No.22 Submarine Ro-14	Kure Naval Arsenal	14-09-1918	31-03-1919	17-02-1921	Renamed Ro-14 01-11-1924. Decommissioned 01-09-1933.
  No.24 Submarine Ro-15	Kure Naval Arsenal	12-06-1920	14-10-1920	30-06-1921	Renamed Ro-15 01-11-1924. Decommissioned 01-09-1933.

Kaichū III (Ro-16 class)

Project number S18. Their project number was the same as in the Kaichū II type submarine, however their performance was improved.

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Fate
  No.37 Submarine Ro-16	Kure Naval Arsenal	18-11-1920	22-04-1921	29-04-1922	Renamed Ro-16 01-11-1924. Decommissioned 01-09-1933.
  No.34 Submarine Ro-17	Kure Naval Arsenal	24-09-1920	24-02-1921	20-10-1921	Renamed Ro-17 01-11-1924. Decommissioned 01-04-1936.
  No.35 Submarine Ro-18	Kure Naval Arsenal	20-10-1920	25-03-1921	15-12-1921	Renamed Ro-18 01-11-1924. Decommissioned 01-04-1936.
  No.36 Submarine Ro-19	Kure Naval Arsenal	09-09-1920	28-12-1920	15-03-1922	Renamed Ro-19 01-11-1924. Decommissioned 01-04-1936.
  No.38 Submarine Ro-20	Yokosuka Naval Arsenal Yokosuka Naval Arsenal was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy, and was located at Yokosuka city, Kanagawa prefecture on Tokyo Bay, south of Yokohama...	28-07-1919	26-10-1920	01-02-1922	Renamed Ro-20 01-11-1924. Decommissioned 01-04-1934.
  No.39 Submarine Ro-21	Yokosuka Naval Arsenal	28-07-1919	26-10-1920	01-02-1922	Renamed Ro-21 01-11-1924. Decommissioned 01-04-1934.
  No.40 Submarine Ro-22	Yokosuka Naval Arsenal	22-01-1921	15-10-1921	10-10-1922	Renamed Ro-22 01-11-1924. Decommissioned 01-04-1934.
  No.41 Submarine Ro-23	Yokosuka Naval Arsenal	22-01-1921	15-10-1921	28-04-1923	Renamed Ro-23 01-11-1924. Decommissioned 01-04-1935.
  No.42 Submarine Ro-24	Sasebo Naval Arsenal Sasebo Naval Arsenal was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy. -History:The Sasebo Naval District was established at Sasebo, Nagasaki in 1886, as the third of the naval districts responsible for the defense of the Japanese home islands. After the establishment of the...	21-04-1919	08-12-1919	30-11-1920	Renamed Ro-24 01-11-1924. Decommissioned 01-04-1935.
  No.43 Submarine Ro-25	Sasebo Naval Arsenal	19-02-1920	17-07-1920	25-10-1921	Renamed Ro-25 01-11-1924. Decommissioned 01-04-1936.

Kaichū IV (Ro-26 class)

Project number S18A. Improved model from the Kaichū III type.

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Fate
  No.45 Submarine Ro-26	Sasebo Naval Arsenal	10-03-1921	18-10-1921	25-01-1923	Renamed Ro-26 01-11-1924. Decommissioned 01-04-1940. Scrapped 1948. Her anchor is displaying at Yokosuka Naval Base United States Fleet Activities Yokosuka U.S. Fleet Activities Yokosuka, or Commander, Fleet Activities Yokosuka is a United States Navy base, in Yokosuka, Japan. Its mission is to maintain and operate base facilities for the logistic, recreational, administrative support and service of the U.S. Naval Forces Japan, U.S. 7th Fleet and... .
  No.58 Submarine Ro-27	Yokosuka Naval Arsenal	16-07-1921	22-07-1922	31-07-1924	Renamed Ro-27 01-11-1924. Decommissioned 01-04-1936. Scrapped 1948.
  No.62 Submarine Ro-28	Sasebo Naval Arsenal	10-11-1921	13-04-1922	30-11-1923	Renamed Ro-28 01-11-1924. Decommissioned 01-04-1940. Scrapped 1948.

Kaichū V (Toku-Chū, Ro-29 class)

Project number S18B. They were built for economic-warfare role. The IJN official designation of these boats was .

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Fate
  No.68 Submarine Ro-29	Kawasaki Kawasaki Shipbuilding Corporation -External links:*... -Kōbe Shipyard	02-06-1921	05-12-1922	15-09-1923	Renamed Ro-29 01-11-1924. Decommissioned 01-04-1936.
  No.69 Submarine Ro-30	Kawasaki-Kōbe Shipyard	27-06-1921	18-01-1923	29-04-1924	Renamed Ro-30 01-11-1924. Decommissioned 01-04-1942. Scrapped 1945.
  No.70 Submarine	Kawasaki-Kōbe Shipyard	25-09-1921	15-02-1923		Lost in an accident off Awaji Island Awaji Island is an island in Hyōgo Prefecture, Japan, in the eastern part of the Seto Inland Sea between the islands of Honshū and Shikoku. The island has an area of 592.17 km²...  21-08-1923. Salvaged and scrapped October 1923. Her materials were used for Ro-31.
  Ro-31	Kawasaki-Kōbe Shipyard	20-12-1924	25-09-1926	10-05-1927	Decommissioned 25-05-1945. Scuttled off Sasebo Sasebo, Nagasaki is a city located in Nagasaki Prefecture, Japan. As of 2011, the city has an estimated population of 259,800 and the density of 609 persons per km². The total area is 426.47 km². The locality is famed for its scenic beauty. The city includes a part of Saikai National Park...  05-04-1946.
  No.71 Submarine Ro-32	Kawasaki-Kōbe Shipyard	24-10-1921	19-03-1923	21-05-1924	Renamed Ro-32 01-11-1924. Decommissioned 01-04-1942. Scrapped 1945.

Kaichū VI (Ro-33 class)

Project number S30. They were planned as a prototype for a mass production submarines in the wartime under the Maru 1 Programme

1st Naval Armaments Supplement Programme (Japan, 1931)

The , otherwise known as the "Circle One" plan was the first of four expansion plans of the Imperial Japanese Navy between 1930 and the start of World War II.-Background:...

.

• Boats in class

  Boat	Builder	Laid down	Launched	Completed	Results	Fate
  Ro-33 Japanese submarine Ro-33 Ro-33 was a Ro-33-class submarine of the Imperial Japanese Navy. Commissioned on October 7, 1935 the submarine saw action for Imperial Japanese forces during the Pacific Campaign of World War II. The submarine was sunk near Port Moresby, Papua New Guinea with all hands by the Royal Australian...	Kure Naval Arsenal	08-08-1933	10-10-1934	07-10-1935	Sank Australian merchant ship Mamutu MV Mamutu MV Mamutu, an Australian merchant ship built in Hong Kong in 1938, was of 300 tons gross, 113 feet in length 113, and a beam of 25 feet. She operated on the Inter-Island trade route for Burns Philp & Company, and at the outbreak of World War II, she was engaged in the evacuation of civilians ahead...  07-08-1942	Sunk by HMAS Arunta HMAS Arunta (I30) HMAS Arunta was a Tribal class destroyer of the Royal Australian Navy . Named for the Arrernte Aborigines, the destroyer was laid down in 1939 and commissioned into the RAN in 1942....  and RAF patrol aircraft off Port Moresby Port Moresby Port Moresby , or Pot Mosbi in Tok Pisin, is the capital and largest city of Papua New Guinea . It is located on the shores of the Gulf of Papua, on the southeastern coast of the island of New Guinea, which made it a prime objective for conquest by the Imperial Japanese forces during 1942–43...  29-08-1942.
  Ro-34 Japanese submarine Ro-34 Ro-34 was a Ro-33-class submarine of the Imperial Japanese Navy. Commissioned on May 31, 1937 the submarine saw action for Imperial Japanese forces during the Pacific Campaign of World War II. The submarine was sunk off the Russell Islands in the Solomons with all hands by the United States Navy...	Mitsubishi Mitsubishi Heavy Industries , or MHI, is a Japanese company. It is one of the core companies of Mitsubishi Group.-History:In 1870 Yataro Iwasaki, the founder of Mitsubishi took a lease of Government-owned Nagasaki Shipyard. He named it Nagasaki Shipyard & Machinery Works, and started the shipbuilding business on a full scale... -Kōbe Shipyard	25-04-1934	12-12-1935	31-05-1937		Sunk by USS O'Bannon USS O'Bannon (DD-450) USS O'Bannon , a Fletcher-class destroyer, was the second ship of the United States Navy to be named for Lieutenant Presley O'Bannon , the Marine Corps's "hero of Derna"....  and USS Strong USS Strong (DD-467) USS Strong , a Fletcher-class destroyer, was the first ship of the United States Navy to be named for Rear Admiral James H. Strong , who distinguished himself at the Battle of Mobile Bay....  near Russell Islands Russell Islands The Russell Islands are two small islands, as well as several islets, of volcanic origin, in the Central Province of the Solomon Islands. They are located approximately 48 km northwest from Guadalcanal. The islands are partially covered in coconut plantations, and have a copra and oil factory at...  06-04-1943.

Kaichū VII (Sen-Chū, Ro-35 class)

Project number S44. The final design in the Kaichū series. They were equipped with a Freon air-conditioner, because the IJN took into consideration that they were to be active on the equator area too. The official IJN designation of these boats was or .

The IJN planned to build these boats under the following Naval Armaments Supplement Programmes:

• 9 boats in the Maru Rin Programme
  Temporal Naval Armaments Supplement Programme (Japan, 1940)
  The is one of the armaments expansion plan of the Imperial Japanese Navy .-Background:In October 1940, the IJN schemed building of the submarines and auxiliary vessels because there was a shortage of them.-Table of vessels:-References:...
  
   (Boat # 201 - 209)
• 12 boats in the Maru Kyū Programme (Boat # 385 - 396)
• 15 boats in the Maru Tui Programme
  Additional Naval Armaments Supplement Programme (Japan, 1941)
  The was one of the naval expansion plans of the Imperial Japanese Navy .-Background:In November 1941, the IJN required many additional submarines for the Pacific War, as a pressing matter. To meet this need, the IJN negotiated with the Ministry of Finance and received approval for 32 submarines...
  
   (Boat # 640 - 654)
• 43 boats in the Kai-Maru 5 Programme
  Modified 5th Naval Armaments Supplement Programme (Japan, 1942)
  The was one of the wartime armaments expansion plans of the Imperial Japanese Navy .-Background:In September 1942, after being defeated in the Battle of Midway, the IJN drew up a new armaments expansion plan. This plan was combined by the 5th Naval Armaments Supplement Programme and the 6th Naval...
  
   (Boat # 5181 - 5223)

However some of the boats were cancelled and their naval budgets, materials and staffs were transferred to the I-201 class submarines.

• Boats in class

  Boat No.	Boat	Builder	Laid down	Launched	Completed	Results	Fate
  201	Ro-35	Mitsubishi-Kōbe Shipyard	09-10-1941	09-06-1942	25-03-1943		Sunk by USS Patterson USS Patterson (DD-392) USS Patterson , a , was the 2nd ship of the United States Navy to be named for Daniel Todd Patterson, an officer of the US Navy that served in the Quasi-War with France, First Barbary War, and the War of 1812....  near of Espiritu Santo Espiritu Santo Espiritu Santo is the largest island in the nation of Vanuatu, with an area of . It belongs to the archipelago of the New Hebrides in the Pacific region of Melanesia. It is in the Sanma Province of Vanuatu....  25-08-1943.
  202	Ro-36	Mitsubishi-Kōbe Shipyard	07-03-1942	14-10-1942	27-05-1943		Sunk by USS Melvin USS Melvin (DD-680) USS Melvin , a Fletcher-class destroyer, was the second ship of the United States Navy to be named for Lieutenant, junior grade John T. Melvin ....  north of Saipan Saipan Saipan is the largest island of the United States Commonwealth of the Northern Mariana Islands , a chain of 15 tropical islands belonging to the Marianas archipelago in the western Pacific Ocean with a total area of . The 2000 census population was 62,392...  13-06-1944.
  203	Ro-37	Sasebo Naval Arsenal	09-10-1941	30-06-1942	30-06-1943	Damaged USS Cache USS Cache (AO-67) USS Cache was a Type T2-SE-A1 Suamico-class fleet oiler of the United States Navy.The ship was built at the Sun Shipbuilding and Drydock Co. in Chester, Pennsylvania as the SS Stillwater , under a Maritime Commission contract . Launched on 7 September 1942, sponsored by Mrs. J...  22-01-1944	Sunk by USS Buchanan USS Buchanan (DD-484) USS Buchanan , a Gleaves-class destroyer, was the 2nd ship of the United States Navy to be named for Franklin Buchanan, who was an officer in the U.S...  near of Santa Cruz Islands Santa Cruz Islands The Santa Cruz Islands are a group of islands in the Pacific Ocean, part of Temotu Province of the Solomon Islands. They lie approximately 250 miles to the southeast of the Solomon Islands Chain...  11°47′S 164°17′E 22-01-1944.
  204	Ro-38	Mitsubishi-Kōbe Shipyard	20-06-1942	24-12-1942	24-07-1943		Disappeared after 19-11-1943.
  205	Ro-39	Mitsubishi-Kōbe Shipyard	08-08-1942	06-03-1943	12-09-1943		Sunk by USS Charrette USS Charrette (DD-581) USS Charrette was a of the United States Navy, named for Lieutenant George Charrette , who was awarded the Medal of Honor for heroism during the Spanish-American War....  and USS Fair USS Fair (DE-35) USS Fair was a ship named by the United States Navy for Lieutenant, junior grade Victor Norman Fair, Jr., who was born on 15 August 1921 in Lincoln County, North Carolina, enlisted in the Naval Reserve on 15 August 1940, and was commissioned ensign on 14 March 1941...  east of Wotje Atoll Wotje Atoll Wotje Atoll is a coral atoll of 75 islands in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. Wotje's land area of , is one the largest in the Marshall Islands, and encloses a lagoon of . The atoll is oriented east and west and is at its longest...  06°48′N 168°08′E 03-02-1944.
  206	Ro-40	Mitsubishi-Kōbe Shipyard	08-08-1942	06-03-1943	28-09-1943		Sunk by USS Phelps USS Phelps (DD-360) USS Phelps was a World War II-era Porter-class destroyer in the service of the United States Navy. She was named for Thomas Stowell Phelps. Phelps was laid down 2 January 1934 by Bethlehem Shipbuilding Corporation, Quincy, Massachusetts; launched 18 July 1935; sponsored by Mrs. Richard A. Kearny;...  north of Marshall Islands Marshall Islands The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...  09°50′N 166°35′E 16-02-1944.
  207	Ro-41	Mitsubishi-Kōbe Shipyard	06-10-1942	05-05-1943	26-11-1943	Sank USS Shelton USS Shelton (DE-407) The USS Shelton was a John C. Butler-class destroyer escort built for the United States Navy during World War II. Named for Ensign James A. Shelton, , she was the first of two U.S...  03-10-1944	Sunk by USS Haggard USS Haggard (DD-555) USS Haggard was a Fletcher-class destroyer of the United States Navy named for Captain Haggard of the Louisa, who fought in the Quasi-War....  south of Okinawa 22°57′N 132°19′E 23-03-1945.
  208	Ro-42	Sasebo Naval Arsenal	27-04-1942	25-10-1942	31-08-1943		Sunk by USS Bangust USS Bangust (DE-739) USS Bangust was a built for the United States Navy during World War II. She served in the Atlantic Ocean and Pacific Ocean and provided escort service against submarine and air attack for Navy vessels and convoys. She returned to the States at war's end with a near-record setting number of...  northeast of Marshall Islands 10°05′N 168°22′E 10-06-1945.
  209	Ro-43	Mitsubishi-Kōbe Shipyard	06-10-1942	05-06-1943	16-12-1943	Damaged USS Renshaw USS Renshaw (DD-499) USS Renshaw , a , was the third ship of the United States Navy of that name, in honor of Commander William B. Renshaw.Renshaw was laid down 7 May 1942 by the Federal Shipbuilding & Drydock Company in Kearny, New Jersey; launched on 13 October 1942, sponsored by Miss Dorothy Lillian Renshaw; and...  21-02-1945	Sunk by aircraft from USS Anzio USS Anzio (CVE-57) USS Anzio , was an Casablanca class escort carrier of the United States Navy.Originally classified as auxiliary aircraft carrier ACV-57, was laid down on 12 December 1942 by the Kaiser Shipbuilding Co., Vancouver, Washington, under a Maritime Commission contract ; named Alikula Bay on 22 January...  off Iwo Jima Iwo Jima Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...  25°07′N 140°19′E 27-02-1945.
  385	Ro-44	Mitsui Mitsui is one of the largest corporate conglomerates in Japan and one of the largest publicly traded companies in the world.-History:Founded by Mitsui Takatoshi , who was the fourth son of a shopkeeper in Matsusaka, in what is now today's Mie prefecture... -Tamano Shipyard	14-02-1942	11-11-1942	13-09-1943		Sunk by USS Burden R. Hastings USS Burden R. Hastings (DE-19) USS Burden R. Hastings was an of the United States Navy during World War II. Immediately after being built, she was crewed and send to the Pacific Ocean to escort convoys and to protect them from air and submarine attack. During her wartime service, she was credited with having sunk one Japanese...  near of Enewetak Enewetak Enewetak Atoll is a large coral atoll of 40 islands in the Pacific Ocean, and forms a legislative district of the Ralik Chain of the Marshall Islands. Its land area totals less than , surrounding a deep central lagoon, in circumference...  11°13′N 164°15′E 16-06-1944.
  386	Ro-45 Japanese submarine RO-45 Ro-45 was an Ro-35-class submarine of the Japanese Navy during World War II. It was completed and commissioned at Mitsubishi Shipbuilding on January 11, 1944. It was based in the Maizuru Naval District under the command of Commander Hamazumi Yoshihisa. It was later reassigned to the Sixth Fleet...	Mitsubishi-Kōbe Shipyard	20-10-1942	21-07-1943	11-01-1944		Sunk by USS Macdonough USS Macdonough (DD-351) The third USS Macdonough was a Farragut-class destroyer in the United States Navy during World War II. She was named for Thomas Macdonough.... , USS Stephen Potter USS Stephen Potter (DD-538) USS Stephen Potter , a , was a ship of the United States Navy named for Ensign Stephen Potter , a naval aviator during World War I....  and aircraft from USS Monterey USS Monterey (CVL-26) USS Monterey was an Independence-class light aircraft carrier of the United States Navy, in service during World War II and used in training for several years thereafter....  south of Truk Chuuk Chuuk — formerly Truk, Ruk, Hogoleu, Torres, Ugulat, and Lugulus — is an island group in the south western part of the Pacific Ocean. It comprises one of the four states of the Federated States of Micronesia , along with Kosrae, Pohnpei, and Yap. Chuuk is the most populous of the FSM's...  06°13′N 151°19′E 01-05-1944.
  387	Ro-46	Mitsui-Tamano Shipyard	13-06-1942	23-04-1943	19-02-1944	Sank USS Cavalier USS Cavalier (APA-37) USS Cavalier was a in the United States Navy. She was named for Cavalier County, North Dakota.Cavalier was reclassified APA-37, 1 February 1943; launched 15 March 1943 by the Western Pipe and Steel Company, San Francisco, California; sponsored by Mrs. M. W...  29-01-1945	Sunk by aircraft from USS Tulagi USS Tulagi (CVE-72) USS Tulagi was a of the United States Navy.She was laid down on 7 June 1943 at Vancouver, Washington, United States, by the Kaiser Company, Inc., as Fortazela Bay ; and redesignated CVE-72 on 15 July 1943...  near of Oki Daitō Oki Daito , also spelled as Oki Daitō or Oki-Daitō, previously known as , is an uninhabited island in the Daitō island group southeast of Okinawa, Japan. It belongs to Kitadaitō Village. It was formally incorporated into Japan in 1900....  24°15′N 131°16′E 29-04-1945.
  388	Ro-47	Mitsubishi-Kōbe Shipyard	28-12-1942	20-08-1943	31-01-1944		Sunk by USS McCoy Reynolds USS McCoy Reynolds (DE-440) USS McCoy Reynolds was a acquired by the U.S. Navy during World War II. The primary purpose of the destroyer escort was to escort and protect ships in convoy, in addition to other tasks as assigned, such as patrol or radar picket...  northeast of Palau Palau Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...  09°19′N 136°44′E 26-09-1944.
  389	Ro-48	Mitsubishi-Kōbe Shipyard	17-03-1943	15-10-1943	31-03-1944		(1) Sunk by USS William C. Miller USS William C. Miller (DE-259) USS William C. Miller was an constructed for the United States Navy during World War II. She was sent off into the Pacific Ocean to protect convoys and other ships from Japanese submarines and fighter aircraft...  northwest of Saipan 14-07-1944. (2) Sunk by USS Wyman USS Wyman (DE-38) USS Wyman was an of the United States Navy during World War II. She was promptly sent off into the Pacific Ocean to protect convoys and other ships from Japanese submarines and fighter aircraft...  northwest of Saipan 18-07-1944.
  390	Ro-49	Mitsui-Tamano Shipyard	16-11-1942	03-08-1943	19-05-1944		Disappeared after 25-03-1945.
  391	Ro-50	Mitsui-Tamano Shipyard	18-02-1943	27-11-1943	31-07-1944	Sank USS LST-577 11-02-1945	Decommissioned 30-11-1945. Sunk as target off Gotō Islands Goto Islands The are Japanese islands in the East China Sea, off the western coast of Kyūshū. The islands are a part of Nagasaki Prefecture.- Geography :There are 140 islands in total, including five main islands:,,,, and....  01-04-1946.
  392 - 395							Cancelled in 1943.
  396	Ro-55	Mitsui-Tamano Shipyard	05-08-1943	23-04-1944	30-09-1944		Sunk by USS Thomason USS Thomason (DE-203) USS Thomason was a Buckley-class destroyer escort of the United States Navy in World War II. She was named in honor of Marine Raider Sergeant Clyde A...  west of Luzon Luzon Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...  15°27′N 119°25′E 07-02-1945.
  640 - 644							Cancelled in 1943.
  645	Ro-56	Mitsui-Tamano Shipyard	02-12-1943	05-07-1944	15-11-1944		Sunk by USS Mertz USS Mertz (DD-691) USS Mertz was a World War II-era Fletcher-class destroyer in the service of the United States Navy, named after Rear Admiral Albert Mertz....  and USS Monssen USS Monssen (DD-798) USS Monssen was a Fletcher-class destroyer of the United States Navy, the second Navy ship named for Lieutenant Mons Monssen , who was awarded the Medal of Honor for putting out a fire in a magazine on Missouri ....  near of Oki Daitō 26°09′N 130°21′E 09-04-1945.
  646 - 654							Cancelled in 1943.
  5181 - 5223							Cancelled in 1943.

Characteristics

Type		Kaichū I (Ro-11)	Kaichū II (Ro-13)	Kaichū III (Ro-16)	Kaichū IV (Ro-26)
Displacement	Surfaced	720 long tons (732 t)	740 long tons (752 t)	740 long tons (752 t)	750 long tons (762 t)
	Submerged	1000 long tons (1,016 t)	1003.1 long tons (1,019 t)	997 long tons (1,013 t)	1080 long tons (1,097 t)
Length (overall)		69.19 metre	70.1 metre	70.1 metre	74.22 metre
Beam		6.35 metre	6.1 metre	6.12 metre	6.12 metre
Draft		3.43 metre	3.68 metre	3.7 metre	3.73 metre
Power plant and shaft		2 × Sulzer Sulzer (manufacturer) Sulzer Ltd. is a Swiss industrial engineering and manufacturing firm, founded by Salomon Sulzer-Bernet in 1775 and established as Sulzer Brothers Ltd. in 1834 in Winterthur, Switzerland. Today it is a publicly owned company with international subsidiaries...  Mk.2 diesels 2 shafts	2 × Sulzer Mk.2 diesels 2 shafts	2 × Sulzer Mk.2 diesels 2 shafts	2 × Sulzer Mk.2 diesels 2 shafts
Power	Surfaced	2,900 bhp	2,900 bhp	2,900 bhp	2,900 bhp
	Submerged	1,200 shp	1,200 shp	1,200 shp	1,200 shp
Speed	Surfaced	18.2 knots (35.7 km/h)	16.5 knots (32.3 km/h)	16.5 knots (32.3 km/h)	16 knots (31.4 km/h)
	Submerged	9.1 knots (17.8 km/h)	8.5 knots (16.7 km/h)	8.5 knots (16.7 km/h)	8.5 knots (16.7 km/h)
Range	Surfaced	4000 nmi (7,408 km) at 10 knots (19.6 km/h)	6000 nmi (11,112 km) at 10 knots (19.6 km/h)	6000 nmi (11,112 km) at 10 knots (19.6 km/h)	6000 nmi (11,112 km) at 10 knots (19.6 km/h)
	Submerged	85 nmi (157.4 km) at 4 knots (7.8 km/h)	85 nmi (157.4 km) at 4 knots (7.8 km/h)	85 nmi (157.4 km) at 4 knots (7.8 km/h)	85 nmi (157.4 km) at 4 knots (7.8 km/h)
Test depth		30 m (98.4 ft)	30 m (98.4 ft)	45.7 m (149.9 ft)	45.7 m (149.9 ft)
Fuel		58.4 tons	75 tons	75 tons	75 tons
Complement		43	43	46	46
Armament (initial)		• 6 × 450 mm (18 in) TT Torpedo tube A torpedo tube is a 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 installed aboard surface vessels... s (4 × front, 2 × turret) • 10 × Type 44 torpedoes • 1 × 76.2 mm (3 in) L/23.5 5th Year Type AA gun	• 6 × 450 mm (18 in) TTs (4 × front, 2 × upper deck) • 10 × Type 44 torpedoes • 1 × 76.2 mm (3 in) L/23.5 5th Year Type AA gun	• 6 × 450 mm (18 in) TTs (4 × front, 2 × upper deck) • 10 × Type 44 torpedoes • 1 × 76.2 mm (3 in) L/23.5 5th Year Type AA gun	• 4 × 533 mm (21 in) TTs (4 × front) • 8 × 6th Year Type torpedoes • 1 × 76.2 mm (3 in) L/23.5 5th Year Type AA gun

Type		Kaichū V (Ro-29)	Kaichū VI (Ro-33)	Kaichū VII (Ro-35)
Displacement	Surfaced	852 long tons (866 t)	700 long tons (711 t)	960 long tons (975 t)
	Submerged	1030 long tons (1,047 t)	1200 long tons (1,219 t)	1447 long tons (1,470 t)
Length (overall)		74.22 metre	73 metre	80.5 metre
Beam		6.12 metre	6.7 metre	7.05 metre
Draft		3.73 metre	3.25 metre	4.07 metre
Power plant and shaft		2 × Sulzer Mk.1 diesels 2 shafts	2 × Kampon Imperial Japanese Navy Technical Department The was the externally operating division of the Ministry of the Navy of Japan responsible for the administration of naval vessel construction. From 1923 onward, it took on the role of a research institution for the research and development of naval technologies and engineering...  Mk.21 Model 8 diesels 2 shafts	2 × Kampon Mk.22 Model 10 diesels 2 shafts
Power	Surfaced	1,200 bhp	3,000 bhp	4,200 bhp
	Submerged	1,200 shp	1,200 shp	1,200 shp
Speed	Surfaced	13 knots (25.5 km/h)	19 knots (37.2 km/h)	19.8 knots (38.8 km/h)
	Submerged	8.5 knots (16.7 km/h)	8.2 knots (16.1 km/h)	8 knots (15.7 km/h)
Range	Surfaced	6000 nmi (11,112 km) at 10 knots (19.6 km/h)	8000 nmi (14,816 km) at 12 knots (23.5 km/h)	5000 nmi (9,260 km) at 16 knots (31.4 km/h)
	Submerged	85 nmi (157.4 km) at 4 knots (7.8 km/h)	90 nmi (166.7 km) at 3.5 knots (6.9 km/h)	45 nmi (83.3 km) at 5 knots (9.8 km/h)
Test depth		45.7 m (149.9 ft)	75 m (246.1 ft)	80 m (262.5 ft)
Fuel		143 tons	109 tons	218 tons
Complement		44	61	61
Armament (initial)		• 4 × 533 mm (21 in) TTs (4 × front) • 8 × 6th Year Type torpedoes • 1 × 120 mm (4.7 in) L/45 11th Year Type Naval gun • 1 × 6.5 mm machine gun	• 4 × 533 mm (21 in) TTs (4 × front) • 8 × Type 89 torpedoes • 1 × 76.2 mm (3 in) L/40 11th Year Type AA gun • 1 × 13 mm Type 93 AA gun	• 4 × 533 mm (21 in) TTs (4 × front) • 10 × Type 95 torpedo Type 95 torpedo The Type 95 torpedo was a torpedo of the Imperial Japanese Navy.It was based on the formidable Type 93 torpedo but had a smaller warhead, shorter range and a smaller diameter... es • 1 × 76.2 mm (3 in) L/40 11th Year Type AA gun • 2 × Type 96 25mm AA guns