Design and description
The Type F submarines were designed by the Italian firm Fiat-Laurenti and built under license by Kawasaki at Kobe, Japan. [1] They were the Imperial Japanese Navy′s first true seagoing submarines. [1] When the Japanese adopted a three-tiered classification system of its submarines as first-class ( I ), second-class or medium ( Ro ), and third-class ( Ha ) on 1 November 1924, [2] the Type F submarines were the earliest to receive the second-class classification, [1] as reflected in their low numbers in the Ro series. [1] In fact they were the earliest Japanese submarine classified as anything higher than third-class. They had non-cylindrical hulls intended to provide extra internal space, but the Japanese considered the hulls weak despite the provision of additional scantlings during construction to reinforce them. [1] Because of their disappointing performance, they did not serve as the basis for any later Japanese submarine classes. [1]
The submarines of the F1 subclass displaced 700 tonnes (689 long tons) surfaced and 1,064 tonnes (1,047 long tons) submerged. [1] The submarines were 65.6 meters (215 ft 3 in) long and had a beam of 6.1 meters (20 ft 0 in) and a draft of 4.2 meters (13 ft 9 in). [1] They had a diving depth of 40 meters (131 ft). [1] For surface running, the submarines were powered by two 1,400- brake-horsepower (1,044 kW) Fiat diesel engines, each driving one propeller shaft. [1] When submerged each propeller was driven by a Savigliano 600-horsepower (447 kW) electric motor. [1] They could reach 13 knots (24 km/h; 15 mph) on the surface and 8 knots (15 km/h; 9.2 mph) underwater. [1] On the surface, they had a range of 3,500 nautical miles (6,500 km; 4,000 mi) at 10 knots (19 km/h; 12 mph); [1] submerged, they had a range of 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph). [1]
The submarines were armed with five 450 mm (18 in) torpedo tubes, three in the bow and two in the stern, and carried a total of eight Type 44 torpedoes. [1] As built, they were armed with a 7.7 mm machine gun. [1] Soon after completion, however, a 76.2 mm (3.00 in) deck gun was added. [1]
Ro-66 was an Imperial Japanese Navy Type L submarine of the L4 subclass. First commissioned in 1927, she served in the waters of Japan prior to World War II. During World War II, she operated in the Central Pacific and supported Japanese forces in the Battle of Wake Island until she sank after a collision in December 1941.
Ro-31, originally named Submarine No. 70, was an Imperial Japanese Navy Kaichu-Type submarine of the Kaichu V subclass. After a diving accident in 1923 prior to completion, she was salvaged, rebuilt, and completed in 1927. She served in a training role during World War II, surrendered at the end of the war in September 1945, and was scuttled in April 1946.
Ro-32, originally named Submarine No. 71, was an Imperial Japanese Navy Kaichu-Type submarine of the Kaichu V subclass. She was in commission from 1924 to 1938, seeing service in the waters of Formosa and Japan, then served as a stationary training hulk during World War II.
Ro-30, originally named Submarine No. 69, was an Imperial Japanese Navy Kaichu-Type submarine of the Kaichu V subclass. She was in commission from 1924 to 1938, seeing service in the waters of Formosa and Japan, then served as a stationary training hulk during World War II.
Ro-29, originally named Submarine No. 68, was an Imperial Japanese Navy Kaichu-Type submarine of the Kaichu V subclass. She was in commission from 1923 to 1936 and saw service in the waters of Formosa and Japan.
Ro-51, originally named Submarine No. 25, was an Imperial Japanese Navy Type L submarine of the L1 subclass. She was in commission from 1920 to 1938.
Ro-52, originally named Submarine No. 26, was an Imperial Japanese Navy Type L submarine of the L1 subclass. She was commissioned in 1920, sank accidentally in 1923 and again in 1925, was refloated and repaired each time, and was decommissioned in 1932.
Ro-53, originally named Submarine No. 27, was an Imperial Japanese Navy Type L submarine, the lead unit of the L2 subclass. She was in commission from 1921 to 1938.
The first Ro-56, originally named Submarine No. 30, was an Imperial Japanese Navy Type L submarine, the final unit of the L2 subclass. Except for a few months in 1926, she was in commission from 1922 to 1938.
Ro-57, originally named Submarine No. 46, was an Imperial Japanese Navy Type L submarine of the L3 subclass. Except for a few months in 1938, she was in commission from 1922 to 1945. During World War II, she served on second-line duties in Japan.
Ro-58, originally named Submarine No. 47, was an Imperial Japanese Navy Type L submarine of the L3 subclass. She was in commission from 1922 to 1945. During World War II, she served on second-line duties in Japan.
Ro-59, originally named Submarine No. 57, was an Imperial Japanese Navy Type L submarine of the L3 subclass. She was in commission from 1923 to 1938, in 1939, and from 1941 to 1945. During World War II, she served on training duties in Japan.
Ro-25, originally named Submarine No. 43, was an Imperial Japanese Navy Kaichū-Type submarine of the Kaichū III subclass. She was commissioned in 1921 and operated in the waters of Japan and Formosa. She sank after a collision in 1924, and after salvage and repairs returned to service from 1925 to 1936.
Ro-24, originally named Submarine No. 42, was an Imperial Japanese Navy Kaichū-Type submarine, the lead unit of the Kaichū III subclass. She was commissioned in 1920 and operated in the waters of Japan, Formosa, and Chōsen before she was stricken in 1935.
Ro-23, originally named Submarine No. 41, was an Imperial Japanese Navy Kaichū-Type submarine of the Kaichū III subclass. She was commissioned in 1923 as the final unit of the Kaichu' III subclass and operated in the waters of Japan, Formosa, and Chōsen before she was stricken in 1935.
The Type F submarines were medium Imperial Japanese Navy submarines in commission during the 1920s. They were Japan's first true seagoing submarines and the earliest Japanese submarines classified as "second-class" or "medium" submarines.
Ro-2, originally named Submarine No. 21, was an Imperial Japanese Navy Type F submarine of the F1 subclass. She and her sister ship Ro-1 were the first truly seagoing Japanese submarines, and the earliest to be classified as "second-class" or "medium" submarines of the Ro series. She was commissioned in 1920 and operated in the waters of Japan. She was stricken in 1932.
Ro-3, originally named Submarine No. 31, was an Imperial Japanese Navy Type F submarine of the F2 subclass. The Type F submarines were the first truly seagoing Japanese submarines, and the earliest to be classified as "second-class" or "medium" submarines of the Ro series. Ro-3 was commissioned in 1922 and operated in the waters of Chōsen and Japan. She was stricken in 1932.
Ro-4, originally named Submarine No. 32, was an Imperial Japanese Navy Type F submarine of the F2 subclass. The Type F submarines were the first truly seagoing Japanese submarines, and the earliest to be classified as "second-class" or "medium" submarines of the Ro series. Ro-4 was commissioned in 1922 and operated in the waters of Chōsen and Japan. She was stricken in 1932.
Ro-5, originally named Submarine No. 33, was an Imperial Japanese Navy Type F submarine of the F2 subclass. The Type F submarines were the first truly seagoing Japanese submarines, and the earliest to be classified as "second-class" or "medium" submarines of the Ro series. Ro-5 was commissioned in 1922 and operated in the waters of Chōsen and Japan. She was stricken in 1932.
Japan