Kaidai-type submarine

Class overview
Name	Kaidai-type submarine
Builders	Kure Naval Arsenal Sasebo Naval Arsenal Yokosuka Naval Arsenal Kawasaki Shipbuilding Mitsubishi Heavy Industries
Operators	Imperial Japanese Navy
Subclasses	Kaidai I (I-51-class) Kaidai II (I-152-class) Kaidai IIIa (I-153-class) Kaidai IIIb (I-156-class) Kaidai IV (I-61/I-162-class) Kaidai V (I-165-class) Kaidai VIa (I-168-class) Kaidai VIb (I-174-class) Kaidai VII (I-176-class)
Built	1921–1943
In commission	1924–1945

The Kaidai-type submarine (海大型潜水艦, Kaidai-gata sensuikan) was a type of first-class submarine operated by the Imperial Japanese Navy (IJN) before and during World War II. The type name was shortened to Kaigun-shiki Ōgata Sensuikan (海軍式大型潜水艦) Navy Large Type Submarine.^[1]

All Kaidai-class submarines originally had a two-digit boat name, from I-51 onwards. On 20 May 1942, all Kaidai submarines added a '1' to their names. For example, I-52 became I-152. Ships are listed by the three-digit boat name if they had one, two-digit if they were not granted one or left service before 20 May 1942.