Classification of Japanese naval vessel
 or coastal defense ship was a type of naval ship used by the Imperial Japanese Navy during World War II for escort duty and coastal defense. The term escort ship was used by the United States Navy to describe this category of Japanese ships.
Description.
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. 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, 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. Additionally, because of these features of Allied destroyer escorts, they are more comparable to the Matsu-class, which the IJN considered to be , envisioned as general escorts with less firepower and speed.
"Kaibōkan" had some counterparts among Japan's Axis allies: the 10 "Kriegsmarine" escort ships of the F-class, and "Amiral Murgescu" of the Romanian Navy.
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.
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".
Footnotes.
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References.
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