page_title: Submarines of the Imperial Japanese Navy
section_title: Kaichū Type (20 units)
hierarchical_section_title: Submarines of the Imperial Japanese Navy / World War II / 2nd class submarines / Kaichū Type (20 units)
caption_attribution_description: Japanese RO-33 submarine
context_page_description: Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one of the world's most varied and powerful submarine fleets.
context_section_description: The Kaichū type (海中型, Navy medium type) submarines were double-hulled medium sized submarines. They were derived from the (Kai)tokuchū or Kaichū V type ((海)特中型 or 海中V型, (Navy) Special purpose-medium type or Navy medium type V) (KT or K5 type, Ro-29-class). Several variants existed. From 1934 to 1944, the Kaichū VI type (海中VI型, Navy medium type VI) (K6 type, Ro-33-class) and the (Sen-)Chū or Kaichū VII type ((潜)中型 or 海中VII型, (Submarine) Medium type or Navy medium type VII) (K7 type, Ro-35-class) were built. The K6 type was equipped with a 3.25 inch (80 mm (3 in)/40) gun and Type 95 Long Lance torpedoes. Twenty units were built: Ro-33, Ro-34, Ro-35, Ro-36, Ro-37, Ro-38, Ro-39, Ro-40, Ro-41, Ro-42, Ro-43, Ro-44, Ro-45, Ro-46, Ro-47, Ro-48, Ro-49, Ro-50, Ro-55, Ro-56.
caption: Kaichū type Ro-33 submarine.
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