These ships were the Japanese equivalent to Allied destroyer escorts and frigates, with all three types of warships being built as a less expensive anti-submarine warfare alternative to fleet destroyers.[3] While similar, destroyer escorts of the US Navy played a slightly different role to that of kaibōkan within the IJN, namely being that kaibōkan were diesel engine ships that never carried torpedo tubes,[2] while many examples of Allied destroyer escort classes featured boiler and turbine machinery, and carried torpedoes; as a result of these design differences, kaibōkan often proved inferior to Allied destroyer escorts when undertaking escort roles.[4] Additionally, because of these features of Allied destroyer escorts, they are more comparable to the Matsu-class, which the IJN considered to be "Type D destroyers" (丁型駆逐艦),[FN 2] envisioned as general escorts with less firepower and speed.[5][6]
In the course of the war, the design was simplified and scaled down to permit larger numbers of vessels to be built more quickly.
Old definition
Before the onset of World War II, kaibōkan was the catchall name for various ships, from battleships to sloops, which had become obsolete. For example, the battleship Mikasa was reclassified as a Kaibokan 1st class in 1921, after 19 years from her commissioning.
Classes
Ships of the first four classes were all named after Japanese islands.
Main Engine: Diesel X 2, double shaft (3,100 kW (4,200 shp))
Max Speed: 36.1 km/h (19.5 kn)
Range: 10,656 kilometres (5,754 nmi) (30 km/h (16 kn))
Fuel: Oil X 120t
Type C and Type D
Same design with different engines; diesels for Type C and turbines for Type D. More than 120 were mass-produced during the war, employing modular design method.
Others
In addition, two former Chinese light cruisers were used, renamed Ioshima and Yasoshima.
^Common alternative English translation of kaibōkan. Not to be confused with "coastal defense ships" of other smaller navies, such as monitors with 12+ inch guns, which fulfilled different roles.
Dodson, Aidan & Cant, Serena (2020). Spoils of War: The Fate of Enemy Fleets after Two World Wars. Barnsley, UK: Seaforth Publishing. ISBN978-1-5267-4198-1.