Imperial Japanese Navy ship classifications

Imperial Japanese Navy ship classifications went through various changes between 1871 and 1945, as technology changed and new ship classes were added while those that became obsolete were discontinued. There were efforts to translate some ships' classes that were imported or in use by other navies, while incorporating any classification system into Japanese language conventions and maintaining an internal consistency.

Classification terminology

These were legal classifications of the naval vessels of the Imperial Japanese Navy. Therefore, those names are different from universal classifications and class names.

In laws, ordinances, regulations, and policies pertaining to the Imperial Japanese Navy, there were no classifications related to the light aircraft carrier, escort carrier, heavy cruiser or light cruiser. Even if it is assumed that these translation were different in the Japanese language, there could be the same phrase and class in English language, and vice versa.

• Example 1: Kōsakukan (工作艦) and Kōsakusen (工作船) = Repair ship.
• Example 2: Fusetukan (敷設艦), Fusetsusen (敷設船), and Fusetsutei (敷設艇) = Minelayer.

The suffix of ship classes could also relate the type or structure of the vessel, which may carry a slightly different connotation than the translated English term. SOme examples:

• -kan (艦) = Vessel or Ship, example: Kōsakukan is Repair vessel; Senkan is a Battleship.
• -sen (船) = Ship, example: Kōsakusen is Repair ship.
• -tei (艇) = Boat, example: Fusetsutei is Mine boat.

Representative classification tables

28 October 1871 (Initial)

• 28 October 1871, Rules of the Navy, and officer's salary schedules, Article 3 and 4, Ministry of War (明治4年10月28日 兵部省 海軍規則並諸官俸給表 第3條および第4條, 1871 Kaigun kisoku narabini shokan hōkyūhyō)

Warship (軍艦, Gunkan)	Large vessel (大艦, Daikan)	1st class warship (一等軍艦, Ittō Gunkan)	Ironclad warship: And over 450 horsepower steamship Others: And over 600 horsepower steamship, or, and over 500 crewmen
		2nd class warship (二等軍艦, Nitō Gunkan)	Ironclad warship: And over 150 hp steamship Others: And over 450 hp steamship, or, and over 300 crewmen
	Medium vessel (中艦, Chūkan)	3rd class warship (三等軍艦, Santō Gunkan)	Ironclad warship: Less than 150 hp steamship Others: And over 250 hp steamship, or, and over 200 crewmen
		4th class warship (四等軍艦, Yontō Gunkan)	And over 150 hp steamship, or, and over 120 crewmen
	Small vessel (小艦, Shōkan)	5th class warship (五等軍艦, Gotō Gunkan)	And over 80 hp steamship, or, and over 50 crewmen
		6th class warship (六等軍艦, Rokutō Gunkan)	And over 50 hp steamship, or, and over 30 crewmen
		7th class warship (七等軍艦, Nanatō Gunkan)	Less than 50 hp steamship, or, and less than 30 crewmen

5 October 1872

• 5 October 1872, Revision of the Naval ship classes (明治5年10月4日 海軍省軍務局 艦船等級更正ノ件, 1872 Kansen tōkyū kōsei-no ken)

Warship	Large vessel	1st class warship	Ironclad warship: And over 170 crewmen Others: And over 455 crewmen
		2nd class warship	Ironclad warship: And over 65 crewmen Others: And over 315 crewmen
		3rd class warship	Ironclad warship: Less than 65 crewmen Others: And over 170 crewmen
	Medium vessel	4th class warship	And over 100 crewmen
		5th class warship	And over 65 crewmen
	Small vessel	6th class warship	And over 40 crewmen
		7th class warship	Less than 39 crewmen
Transport vessel (運送艦, Unsōkan)		4th class transport vessel (四等運送艦, Yontō Unsōkan)	And over 800 tons displacement
		5th class transport vessel (五等運送艦, Gotō Unsōkan)	And over 500 tons displacement
		6th class transport vessel (六等運送艦, Rokutō Unsōkan)	And over 200 tons displacement
		7th class transport vessel (七等運送艦, Nanatō Unsōkan)	And under 200 tons displacement

13 August 1890

• 13 August 1890, Notice No. 291, "Naval ships ordinance, Article 2", Minister's Secretariat (明治23年8月13日 海軍大臣官房 達第291号 海軍艦船籍條例 第2條, 1890 Kaigun kansenseki jōrei)

Naval ships (海軍艦船, Kaigun Kansen)	Category 'A' ship (第一種艦船, Daiisshu Kansen)	Warship as fighting ship (戦闘航海ノ役務ニ堪フル軍艦, Sentōkōkai-no ekimu-ni tauru gunkan)
	Category 'B' ship (第二種艦船, Dainishu Kansen)	Torpedo boat (水雷艇, Suiraitei)
	Category 'C' ship (第三種艦船, Daisanshu Kansen)	Warship as noncombatant ship (戦闘航海ノ役務ニ堪ヘサル軍艦, Sentōkōkai-no ekimu-ni taezaru gunkan)
	Category 'D' ship (第四種艦船, Daiyonshu Kansen)	Transport ship (運送船, Unsōsen), Tugboat (曳船, Eisen) and Small sized steamer (小蒸気船, Shō jōkisen)
	Category 'E' ship (第五種艦船, Daigoshu Kansen)	Storage ship (倉庫船, Sōkosen), Loading ship (荷船, Nisen) and Miscellaneous ship (雑船, Zatsusen)

1 April 1896

• 1896 Imperial edict No. 71, "Naval ships ordinance, Article 3" (明治29年 勅令第71号 海軍艦船條例 第3條, 1896 Chokurei Dai-71-gō, Kaigun kansen jōrei)

Naval ships	Category 'A' warship (第一種軍艦, Daiisshu Gunkan)	Warship as fighting ship
	Category 'B' warship (第二種軍艦, Dainishu Gunkan)	Warship as noncombatant ship
	Torpedo boat	1st class torpedo boat (一等水雷艇, Ittō Suiraitei)
		2nd class torpedo boat (二等水雷艇, Nitō Suiraitei)
		3rd class torpedo boat (三等水雷艇, Santō Suiraitei)
	Miscellaneous ships (雑役船舟, Zatsuekisenshū)

21 March 1898

• Standard classifications of the naval warships and torpedo boats (海軍軍艦及水雷艇類別標準, Kaigun gunkan oyobi suiraitei ruibetsu-hyōjun)

Warships	Battleship (戦艦, Senkan)	1st class battleship (一等戦艦, Ittō Senkan)
		2nd class battleship (二等戦艦, Nitō Senkan)
	Cruiser (巡洋艦, Jun'yōkan)	1st class cruiser (一等巡洋艦, Ittō Jun'yōkan)
		2nd class cruiser (二等巡洋艦, Nitō Jun'yōkan)
		3rd class cruiser (三等巡洋艦, Santō Jun'yōkan)
	Coast defence ship (海防艦, Kaibōkan)	1st class coast defence ship (一等海防艦, Ittō Kaibōkan)
		2nd class coast defence ship (二等海防艦, Nitō Kaibōkan)
		3rd class coast defence ship (三等海防艦, Santō Kaibōkan)
	Gunboat (砲艦, Hōkan)	1st class gunboat (一等砲艦, Ittō Hōkan)
		2nd class gunboat (二等砲艦, Nitō Hōkan)
	Dispatch vessel (通報艦, Tsūhōkan)
	Torpedo boat tender (水雷母艦, Suiraibokan)
Torpedo boat		Torpedo boat destroyer (水雷艇駆逐艇, Suiraiteikuchikutei)
		1st class torpedo boat
		2nd class torpedo boat
		3rd class torpedo boat
		4th class torpedo boat (四等水雷艇, Yontō Suiraitei)

22 June 1900

• Standard classifications of the naval vessels (海軍艦艇類別標準, Kaigun kantei ruibetsu-hyōjun)

Naval vessels (艦艇, Kantei)	Warships	Battleship	1st class battleship
			2nd class battleship
		Cruiser	1st class cruiser
			2nd class cruiser
			3rd class cruiser
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
			3rd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
		Dispatch vessel
		Torpedo boat tender
		Destroyer (駆逐艦, Kuchikukan)
	Torpedo boat		1st class torpedo boat
			2nd class torpedo boat
			3rd class torpedo boat
			4th class torpedo boat

28 August 1912

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Battlecruiser (巡洋戦艦, Jun'yōsenkan)
		Cruiser	1st class cruiser
			2nd class cruiser
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
	Destroyer
	Torpedo boat		1st class torpedo boat
			2nd class torpedo boat
	Submersible (潜水艇, Sensuitei)
Repair ship (工作船, Kōsakusen)
Transport ship
Hospital ship (病院船, Byōinsen)

17 May 1916

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Battlecruiser
		Cruiser	1st class cruiser
			2nd class cruiser
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
	Destroyer		1st class destroyer (一等駆逐艦, Ittō Kuchikukan)
			2nd class destroyer (二等駆逐艦, Nitō Kuchikukan)
			3rd class destroyer (三等駆逐艦, Santō Kuchikukan)
	Torpedo boat		1st class torpedo boat
			2nd class torpedo boat
	Submersible
Auxiliary ships (特務船, Tokumusen)	Repair ship
	Transport ship
	Minelaying ship (敷設船, Fusetsusen)

1 April 1920

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Battlecruiser
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier (航空母艦, Kōkūbokan)
		Torpedo boat tender
		Minelayer (敷設艦, Fusetsukan)
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
	Destroyer		1st class destroyer
			2nd class destroyer
			3rd class destroyer
	Torpedo boat		1st class torpedo boat
			2nd class torpedo boat
	Submarine (潜水艦, Sensuikan)		1st class submarine (一等潜水艦, Ittō Sensuikan)
			2nd class submarine (二等潜水艦, Nitō Sensuikan)
			3rd class submarine (三等潜水艦, Santō Sensuikan)

• Standard classifications of the naval auxiliary vessels (海軍特務艦艇類別標準, Kaigun tokumu-kantei ruibetsu-hyōjun)

Auxiliary vessels (特務艦艇, Tokumu-kantei)	Auxiliary vessel (特務艦, Tokumukan)	Repair vessel (工作艦, Kōsakukan)
		Transport vessel
	Auxiliary boat (特務艇, Tokumutei)	Minesweeper (掃海艇, Sōkaitei)	1st class minesweeper (一等掃海艇, Ittō Sōkaitei)
			2nd class minesweeper (二等掃海艇, Nitō Sōkaitei)
		Submarine depot boat (潜水艦母艇, Sensuikanbotei)

1 December 1924

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Battlecruiser
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier
		Submarine tender (潜水母艦, Sensuibokan)
		Minelayer
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
	Destroyer		1st class destroyer
			2nd class destroyer
			3rd class destroyer
	Submarine		1st class submarine
			2nd class submarine
			3rd class submarine
	Minesweeper

• Standard classifications of the naval auxiliary vessels

Auxiliary vessels	Auxiliary vessel	Repair vessel
		Transport vessel
		Icebreaker (砕氷艦, Saihyōkan)
		Survey ship (測量艦, Sokuryōkan)
		Target ship (標的艦, Hyōtekikan)
		Auxiliary training ship (練習特務艦, Renshūtokumukan)
	Auxiliary boat	Mine boat (敷設艇, Fusetsutei)	1st class mine boat (一等敷設艇, Ittō Fusetsutei)
			2nd class mine boat (二等敷設艇, Nitō Fusetsutei)
			3rd class mine boat (三等敷設艇, Santō Fusetsutei)
		Auxiliary minesweeper (掃海特務艇, Sōkaitokumutei)	1st class auxiliary minesweeper (一等掃海特務艇, Ittō Sōkaitokumutei)
			2nd class auxiliary minesweeper (二等掃海特務艇, Nitō Sōkaitokumutei)
		Submarine depot boat

2 March 1927

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Battlecruiser
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier
		Submarine tender
		Minelayer
		Rapid extension netlayer (急設網艦, Kyūsetsumōkan)
		Coast defence ship	1st class coast defence ship
			2nd class coast defence ship
		Gunboat	1st class gunboat
			2nd class gunboat
	Destroyer		1st class destroyer
			2nd class destroyer
			3rd class destroyer
	Submarine		1st class submarine
			2nd class submarine
			3rd class submarine
	Minesweeper

• Standard classifications of the naval auxiliary vessels

Auxiliary vessels	Auxiliary vessel	Repair vessel
		Transport vessel
		Icebreaker
		Survey ship
		Target ship
		Auxiliary training ship
	Auxiliary boat	Mine boat	1st class mine boat
			2nd class mine boat
			3rd class mine boat
		Capture-net layer (捕獲網艇, Hokakumōtei)
		Auxiliary minesweeper	1st class auxiliary minesweeper
			2nd class auxiliary minesweeper
		Submarine depot boat

30 May 1931

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier
		Submarine tender
		Minelayer
		Coast defence ship
		Gunboat
		Training battleship (練習戦艦, Renshū senkan)
		Training cruiser (練習巡洋艦, Renshū jun'yōkan)
	Destroyer		1st class destroyer
			2nd class destroyer
	Submarine		1st class submarine
			2nd class submarine
	Torpedo boat
	Minesweeper

• Standard classifications of the naval auxiliary vessels

Auxiliary vessels	Auxiliary vessel	Repair vessel
		Transport vessel
		Icebreaker
		Survey ship
		Target ship
		Auxiliary training ship
	Auxiliary boat	Mine boat
		Auxiliary minesweeper
		Submarine depot boat

26 June 1941

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier
		Seaplane tender (水上機母艦, Suijōkibokan)
		Submarine tender
		Minelayer
		Coast defence ship
		Gunboat
		Training battleship
		Training cruiser
	Destroyer		1st class destroyer
			2nd class destroyer
	Submarine		1st class submarine
			2nd class submarine
	Torpedo boat
	Minesweeper
	Submarine chaser (駆潜艇, Kusentei)

• Standard classifications of the naval auxiliary vessels

Auxiliary vessels	Auxiliary vessel	Repair vessel
		Transport vessel
		Icebreaker
		Survey ship
		Target ship
		Auxiliary training ship
	Auxiliary boat	Mine boat
		Auxiliary submarine chaser (駆潜特務艇, Kusentokumutei)
		Auxiliary minesweeper
		Patrol boat (哨戒艇, Shōkaitei)
		Cable layer (電纜敷設艇, Denranfusetsutei)
		Motor torpedo boat (魚雷艇, Gyoraitei)
		Submarine depot boat

30 June 1945 (Final)

• Standard classifications of the naval vessels

Naval vessels	Warships	Battleship
		Cruiser	1st class cruiser
			2nd class cruiser
		Aircraft carrier
		Seaplane tender
		Submarine tender
		Minelayer
		Training battleship
		Training cruiser
	Destroyer		1st class destroyer
			2nd class destroyer
	Submarine		1st class submarine
			2nd class submarine
	Coast defence ship
	Gunboat
	Torpedo boat
	Minesweeper
	Submarine chaser
	Patrol boat
	Landing ship (輸送艦, Yusōkan)		1st class landing ship (一等輸送艦, Ittō Yusōkan)
			2nd class landing ship (二等輸送艦, Nitō Yusōkan)
	Mine boat

• Standard classifications of the naval auxiliary vessels

Auxiliary vessels	Auxiliary vessel	Repair vessel
		Transport vessel
		Icebreaker
		Survey ship
		Target ship
		Auxiliary training ship
	Auxiliary boat	Auxiliary mine boat (敷設特務艇, Fusetsutokumutei)
		Auxiliary submarine chaser
		Auxiliary patrol boat (哨戒特務艇, Shōkaitokumutei)
		Auxiliary minesweeper
		Cable layer
		Motor torpedo boat
		Coast defence boat (海防艇, Kaibōtei)

Detailed classification tables

Battleship

1st class battleship Yashima

Battleship Yamato

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Battleship	1st class battleship	And over 10,000 tons designated displacement
				2nd class battleship	Less than 10,000 tons designated displacement
22 June 1900	Naval Vessels	Warships	Battleship	1st class battleship	Same as on 21 March 1898
				2nd class battleship
12 December 1905	Naval vessels	Warships	Battleship		'Class' was abolished

Battlecruiser

Battlecruiser Ibuki

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
28 August 1912	Naval Vessels	Warships	Battlecruiser
30 May 1931					Abolished and unified to battleship

Cruiser

1st class cruiser Nachi

3rd class cruiser Suma

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Cruiser	1st class cruiser	And over 7,000 tons designated displacement
				2nd class cruiser	And over 3,500 tons designated displacement, less than 7,000 tons designated displacement
				3rd class cruiser	Less than 3,500 tons designated displacement
22 June 1900	Naval Vessels	Warships	Cruiser	1st class cruiser	Same as on 21 March 1898
				2nd class cruiser
				3rd class cruiser
28 August 1912	Naval vessels	Warships	Cruiser	1st class cruiser	And over 7,000 tons designated displacement
				2nd class cruiser	Less than 7,000 tons designated displacement, '3rd class' was abolished.
31 May 1934	Naval vessels	Warships	Cruiser	1st class cruiser	Equipped over 155 mm (6.1 in) gun
				2nd class cruiser	Equipped and under 155 mm (6.1 in) gun

Aircraft carrier

Aircraft carrier Akagi

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 April 1920	Naval Vessels	Warships	Aircraft carrier

Seaplane tender

Seaplane tender Chitose

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
31 May 1934	Naval Vessels	Warships	Seaplane tender		Independent from aircraft carrier

Dispatch vessel

Dispatch vessel Miyako

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Dispatch vessel		Torpedo gunboat was classified to dispatch boat
22 June 1900	Naval vessels	Warships	Dispatch vessel
28 August 1912					Abolished and unified to gunboat

Torpedo boat tender/Submarine tender

Torpedo boat tender Toyohashi

Submarine tender Tsurugizaki

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Torpedo boat tender
22 June 1900	Naval vessels	Warships	Torpedo boat tender
28 August 1912					Abolished and unified to coast defence ship
1 April 1920	Naval vessels	Warships	Torpedo boat tender		Revived
1 December 1924	Naval vessels	Warships	Submarine tender		Renamed

Minelaying ship/Minelayer/Rapid extension netlayer

Minelayer Tsugaru

• Note; pertinence of rapid extension netlayer was only Shirataka.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
17 May 1916	Auxiliary ships		Minelaying ship
1 April 1920	Naval vessels	Warships	Minelayer		Renamed
2 March 1927	Naval vessels	Warships	Minelayer
			Rapid extension netlayer
22 March 1929	Naval vessels	Warships	Minelayer		Rapid extension netlayer was abolished, and unified to minelayer

Training battleship

Training battleship Hiei

• Note; pertinence of training battleship was only Hiei. She does not return to battleship in the Imperial Japanese Navy's official documents.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 May 1931	Naval vessels	Warships	Training battleship

Training cruiser

Training cruiser Katori

• Note; pertinence of training cruiser was only Katori class.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 May 1931	Naval vessels	Warships	Training cruiser

Coast defence ship

2nd class coast defence ship Itsukushima

Coast defence ship Shisaka

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Coast defence ship	1st class coast defence ship	And over 7,000 tons designated displacement
				2nd class coast defence ship	And over 3,500 tons designated displacement, less than 7,000 tons designated displacement
				3rd class coast defence ship	Less than 3,500 tons displacement
22 June 1900	Naval vessels	Warships	Coast defence ship	1st class coast defence ship	Same as on 21 March 1898
				2nd class coast defence ship
				3rd class coast defence ship
28 August 1912	Naval vessels	Warships	Coast defence ship	1st class coast defence ship	And over 7,000 tons designated displacement
				2nd class coast defence ship	Less than 7,000 tons designated displacement
30 May 1931	Naval vessels	Warships	Coast defence ship		'Class' was abolished
1 July 1942	Naval vessels		Coast defence ship (as Escort ship)		Armored cruisers were moved to 1st class cruiser or auxiliary training ship

Gunboat

1st class gunboat Saga

Gunboat Sumida

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Warships		Gunboat	1st class gunboat	And over 1,000 tons designated displacement
				2nd class gunboat	Less than 1,000 tons designated displacement
22 June 1900	Naval vessels	Warships	Gunboat	1st class gunboat	Same as on 21 March 1898
				2nd class gunboat
28 August 1912	Naval vessels	Warships	Gunboat	1st class gunboat	And over 800 tons displacement
				2nd class gunboat	Less than 800 tons displacement
30 May 1931	Naval vessels	Warships	Gunboat		'Class' was abolished
1 October 1944	Naval vessels		Gunboat

Torpedo boat destroyer/Destroyer

1st class destroyer Shimakaze

3rd class destroyer Kagerō

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
21 March 1898	Torpedo boat		Torpedo boat destroyer
22 June 1900	Naval vessels	Warships	Destroyer		Independent from torpedo boat and renamed
12 December 1905	Naval vessels		Destroyer
28 August 1912	Naval vessels		Destroyer	1st class destroyer	And over 1,000 tons designated displacement
				2nd class destroyer	And over 600 tons designated displacement, less than 1,000 tons designated displacement
				3rd class destroyer	Less than 600 tons designated displacement
30 May 1931	Naval vessels		Destroyer	1st class destroyer	And over 1,000 tons designated displacement
				2nd class destroyer	Less than 1,000 tons designated displacement, '3rd class' was abolished
31 May 1934	Naval vessels		Destroyer	1st class destroyer	And over 1,000 tons standard displacement
				2nd class destroyer	Less than 1,000 tons standard displacement

Submersible/Submarine

No. 1-class submersible

1st class submarine I-400

• Note; Kō-hyōteki, Kairyū and Kaiten were not included in this table, because they were weapons in the Imperial Japanese Navy's official documents.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
23 January 1905	Torpedo boat		Submersible
12 December 1905	Naval vessels		Submersible		Independent from torpedo boat
28 August 1912	Naval vessels		Submersible	1st class submersible	And over 600 tons surfaced displacement
				2nd class submersible	Less than 600 tons surfaced displacement
4 April 1919	Naval vessels		Submarine	1st class submarine	Renamed; and over 1,000 tons surfaced displacement
				2nd class submarine	Renamed, and over 600 tons surfaced displacement, less than 1,000 tons surfaced displacement
				3rd class submarine	Less than 600 tons surfaced displacement
30 May 1931	Naval vessels		Submarine	1st class submarine	And over 1,000 tons surfaced displacement
				2nd class submarine	Less than 1,000 tons surfaced displacement, '3rd class' was abolished

Torpedo boat

1st class torpedo boat Hayabusa

2nd class torpedo boat No. 21

3rd class torpedo boat No. 14

Torpedo boat Kiji

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
13 August 1890	Naval ships	Category 'B' warship	Torpedo boat
19 October 1893	Naval ships	Category 'B' warship	Torpedo boat	1st class torpedo boat	And over 70 tons displacement
				2nd class torpedo boat	And over 20 tons designated displacement, less than 70 tons designated displacement
				3rd class torpedo boat	Less than 20 tons designated displacement (vedette boat)
28 March 1896	Naval ships		Torpedo boat	1st class torpedo boat	Same as on 19 October 1893
				2nd class torpedo boat
				3rd class torpedo boat
21 March 1898			Torpedo boat	Torpedo boat destroyer
				1st class torpedo boat	And over 120 tons designated displacement
				2nd class torpedo boat	And over 70 tons designated displacement, less than 120 tons designated displacement
				3rd class torpedo boat	And over 20 tons designated displacement, less than 70 tons designated displacement
				4th class torpedo boat	Less than 20 tons designated displacement (vedette boat)
22 June 1900	Naval vessels		Torpedo boat	1st class torpedo boat	Same as on 21 March 1898; Torpedo boat destroyer was independent from torpedo boat, and renamed destroyer.
				2nd class torpedo boat
				3rd class torpedo boat
				4th class torpedo boat
23 January 1905	Naval vessels		Torpedo boat	1st class torpedo boat	Same as on 21 March 1898
				2nd class torpedo boat
				3rd class torpedo boat
				4th class torpedo boat
				Submersible	IJN called Special-Torpedo boat (特号水雷艇, Tokugō-Suiraitei) for counterintelligence
12 December 1905	Naval vessels		Torpedo boat	1st class torpedo boat	Same as on 21 March 1898 Submersible was independent from torpedo boat.
				2nd class torpedo boat
				3rd class torpedo boat
				4th class torpedo boat
28 August 1912	Naval vessels		Torpedo boat	1st class torpedo boat	And over 120 tons designated displacement
				2nd class torpedo boat	Less than 120 tons designated displacement
15 January 1924					Abolished
30 May 1931	Naval vessels		Torpedo boat		Revived by the London Naval Treaty

Mine boat/Capture-net layer

2nd class mine boat Tsubame

Mine boat Kamishima

• Note; pertinence of capture net layer was only Tsubame class.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 July 1920	Auxiliary vessels	Auxiliary boat	Mine boat	1st class mine boat	And over 800 tons displacement
				2nd class mine boat	And over 400 tons designated displacement, less than 800 tons designated displacement
				3rd class mine boat	Less than 400 tons designated displacement
2 March 1927	Auxiliary vessels	Auxiliary boat	Mine boat	1st class mine boat	Same as on 1 July 1920
				2nd class mine boat
				3rd class mine boat
			Capture-net layer
22 March 1929	Auxiliary vessels	Auxiliary boat	Mine boat	1st class mine boat	Same as on 1 July 1920; capture-net layer was abolished and unified to mine boat
				2nd class mine boat
				3rd class mine boat
30 May 1931	Auxiliary vessels	Auxiliary boat	Mine boat		'Class' was abolished
1 February 1944	Naval vessels		Mine boat

Auxiliary minelayer

Auxiliary minelayer No. 1

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 February 1944	Auxiliary vessels	Auxiliary boat	Auxiliary minelayer		Divided from mine boat

Cable layer

Cable layer Hashima

• Note; pertinence of cable layer was only Hashima class.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
25 October 1940	Auxiliary vessels	Auxiliary boat	Cable layer		Independent from miscellaneous ship

Minesweeper

Minesweeper No. 4

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 April 1920	Auxiliary vessels	Auxiliary boat	Minesweeper	1st class minesweeper	And over 500 tons designated displacement
				2nd class minesweeper	Less than 500 tons designated displacement
30 June 1923	Naval vessels		Minesweeper		'Class' was abolished

Auxiliary minesweeper

Auxiliary minesweeper No. 1

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 June 1923	Auxiliary vessels	Auxiliary boat	Auxiliary minesweeper	1st class auxiliary minesweeper	And over 500 tons designated displacement
				2nd class auxiliary minesweeper	Less than 500 tons designated displacement
30 May 1931	Auxiliary vessels	Auxiliary boat	Auxiliary minesweeper		'Class' was abolished

Submarine chaser

Submarine chaser No. 8

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
23 May 1933	Auxiliary vessels	Auxiliary boat	Submarine chaser
1 April 1940	Naval vessels		Submarine chaser

Auxiliary submarine chaser

Auxiliary submarine chaser No. 1 class

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 April 1940	Auxiliary vessels	Auxiliary boat	Auxiliary submarine chaser		Divided from submarine chaser

Patrol boat

Patrol boat No. 35

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 March 1940	Auxiliary vessels	Auxiliary boat	Patrol boat
15 February 1943	Naval vessels		Patrol boat

Auxiliary patrol boat

Auxiliary patrol boat No. 173

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
15 February 1943	Auxiliary vessels	Auxiliary boat	Auxiliary patrol boat		Divided from patrol boat

Landing ship

2nd class landing ship No. 151

• Note 1; pertinence of 1st class landing ship was only No.1 class.
• Note 2; pertinence of 2nd class lamding ship was only No.101 class.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
5 February 1944	Naval vessels		Landing ship	1st class landing ship	And over 1,000 tons displacement
				2nd class landing ship	Less than 1,000 tons designated displacement

Motor torpedo boat

Motor torpedo boat No. 2

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 June 1941	Auxiliary vessels	Auxiliary boat	Motor torpedo boat		Independent from miscellaneous ship

Coast defence boat

• Note; there is not a ship classed on this table. All No.1-class and No.101-class vessels were incomplete.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 June 1945	Auxiliary vessels	Auxiliary boat	Coast defence boat

Repair ship/Repair vessel

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
12 December 1905			Repair ship
17 May 1916	Auxiliary ships		Repair ship
1 April 1920	Auxiliary vessels	Auxiliary vessel	Repair vessel		Renamed, small sized repair ships were moved to miscellaneous ship

Transport vessel/Transport ship

Transport vessel (Oiler) Hayatomo

• Note; Included replenishment oiler (給油船/給油艦, Kyūyusen/Kyūyukan), collier (給炭船/給炭艦, Kyūtansen/Kyūtankan), collier-oiler (給炭油艦, Kyūtan'yukan), munition ship (給兵艦, Kyūheikan), food supply ship (給糧艦, Kyūryōkan) and freighter (雑用艦, Zatsuyōkan).

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
5 October 1872	Transport vessel		4th class transport vessel		And over 800 tons displacement
			5th class transport vessel		And over 500 tons displacement
			6th class transport vessel		And over 200 tons displacement
			7th class transport vessel		And under 200 tons displacement
13 August 1890	Vessels	Category 'D' warship	Transport ship
1 April 1896	Vessels	Miscellaneous ships	Transport ship
12 December 1905			Transport ship		Independent from miscellaneous ships
17 May 1916	Auxiliary ships		Transport ship
1 April 1920	Auxiliary vessels	Auxiliary vessel	Transport vessel

Hospital ship

• Note; there is not a ship classed on this table.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
12 December 1905			Hospital ship
17 May 1916					Abolished

Icebreaker

Icebreaker Ōtomari

• Note; pertinence of icebreaker was only Ōtomari.

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
3 August 1921	Auxiliary vessels	Auxiliary vessel	Icebreaker

Survey ship

Survey ship Tsukushi

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
31 March 1922	Auxiliary vessels	Auxiliary vessel	Survey ship

Target ship

• This section treats a self-propelled target ship. Towed target ship is miscellaneous ship.

Target ship Settsu

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
29 September 1923	Auxiliary vessels	Auxiliary vessel	Target ship

Auxiliary training ship

Auxiliary training ship Shikishima

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
30 November 1922	Auxiliary vessels	Auxiliary vessel	Auxiliary training ship

Submarine depot boat

Date	Top classification	Higher classification	Classification	Lower classification	Note, classification boundary
1 July 1920	Auxiliary vessels	Auxiliary boat	Submarine depot boat		Moved from miscellaneous ship
between 1 July 1942–30 September 1944					Abolished

Appendix

Miscellaneous ship

17 September 1903 (Initial)

• 17 September 1903, Notice No. 90, Quorum and kinds of miscellaneous ship in naval units, Minister's Secretariat, Ministry of the Navy (明治36年9月17日 海軍大臣官房 達第90号 海軍各廳附属雑役船ノ種類及定数, 1903 Tatsu Dai-90-Gō, Kaigun kakuchō fuzoku zatsuekisen-no shurui oyobi teisū)

Steamship (汽船, Kisen)	And over 250 tons displacement, and less 400 tons displacement
	150 tons displacement
	80 tons displacement
	60 tons displacement
	35 tons displacement
	16 tons displacement
	12.5 tons displacement
	And less 10 tons displacement
Boat (端舟, Hashibune)	38 feet launch
	32 feet pinnace
	30 feet cutter
	28 feet cutter
	26 feet cutter
	23 feet cutter
	30 feet gig
	27 feet gig
	25 feet gig
Yard auxiliary ship (雑船, Zatsusen)	Rigged torpedo boat (帆装水雷船, Hansō suiraisen)
	Dredger (泥浚船, Deishunsen)
	Mechanical dredger (泥浚器船, Deishunkisen); dipper dredger, bucket dredger, grab dredger and pump dredger
	Drilling ship (岩砕船, Gansaisen)
	Water supply ship (水船, Suisen)	Steamer (汽走, Kisō); and over 150 tons loadage, and less 300 tons loadage
		Western style ship (西洋形, Seiyōgata); and over 100 tons loadage, and less 200 tons loadage
		Japanese style ship (和形, Wagata); and over 10 tons loadage, and less 30 tons loadage
	Barge (運貨船, Unkasen); And over 50 tons loadage, and less 100 tons loadage
	Coal supply ship (石炭船, Sekitansen); And over 50 tons loadage, and less 150 tons loadage
	Lighter (五大力船, Godairikisen); And over 20 tons loadage, and less 30 tons loadage
	Hopper barge (泥受船, Doroukesen)
	Junk (伝馬船, Tenmasen)
	High-speed oars (押送船, Oshokurisen)
	Floating pier (足場船, Ashibasen); And over 30 feet, and less 46 feet
	Dumper (塵芥船, Jinkaisen)
	Floating crane (起重器船, Kijūkisen)	50 tons ability
		15 tons ability
	Floating drydock (浮船渠, Ukisenkyo)
	Pile driver (杭打器船, Kuiuchikisen)
	Pontoon (橋船, Kyōsen)
	Training ship (練習船, Renshūsen)

Converted merchant ship classification tables

23 December 1916 (Initial)

• 23 December 1916, Ministerial ordinance No. 281, Special service ships and units ordinance, Minister's Secretariat, Ministry of the Navy (大正5年12月23日 海軍大臣官房 内令第281号 特設艦船部隊令, 1916 Nairei Dai-281-Gō, Tokusetsukansen butairei)

Converted merchant vessels (特設艦船, Tokusetsu kansen)	Converted merchant cruiser (特設巡洋艦, Tokusetsu jun'yōkan)
	Converted merchant torpedo recovery ship (特設水雷母艦, Tokusetsu suiraibokan)
	Converted merchant air group carrier (特設航空隊母艦, Tokusetsu kōkūtaibokan)
	Converted merchant minesweeper division depot ship (特設掃海隊母艦, Tokusetsu sōkaitaibokan)
	Converted merchant gunboat (特設砲艦, Tokusetsu hōkan)
	Converted merchant minesweeper (特設掃海艇, Tokusetsu sōkaitei)
	Converted merchant repair ship (特設工作船, Tokusetsu kōsakusen)
	Converted merchant transport ship (特設運送船, Tokusetsu unsōsen)	Munition and ammunition ship (給兵船, Kyūheisen)
		Water supply ship (給水船, Kyūsuisen)
		Food supply ship (給糧船, Kyūryōsen)
		Collier (給炭船, Kyūtansen)
		Oiler (給油船, Kyūyusen)
		Communication ship (通信船, Tsūshinsen)
		Freighter (雑用船, Zatsuyōsen)
	Converted merchant cable layer (特設電線敷設船, Tokusetsu densenfusetsusen)
	Converted merchant hospital ship (特設病院船, Tokusetsu byōinsen)
	Converted merchant salvage ship (特設救難船, Tokusetsu kyūnansen)

February 1945 (Final)

• February 1945, Ministerial ordinance No. 83, Special service ships and units ordinance, Minister's Secretariat, Ministry of the Navy (昭和20年2月 海軍大臣官房 内令第83号, 1945 Nairei Dai-83-Gō)

Converted merchant vessels	Converted merchant warship (特設軍艦, Tokusetsu gunkan)	Converted merchant cruiser
		Converted merchant minelayer (特設敷設艦, Tokusetsu fusetsukan)
		Converted merchant rapid extension netlayer (特設急設網艦, Tokusetsu kyūsetsumōkan)
		Converted merchant aircraft carrier (特設航空母艦, Tokusetsu kōkūbokan)
		Converted merchant seaplane tender (特設水上機母艦, Tokusetsu suijōkibokan)
		Converted merchant aircraft transport ship (特設航空機運搬艦, Tokusetsu kōkūki unpankan)
		Converted merchant torpedo recovery ship
		Converted merchant submarine tender (特設潜水母艦, Tokusetsu sensuibokan)
		Converted merchant minesweeper tender (特設掃海母艦, Tokusetsu sōkaibokan)
		Converted merchant gunboat
	Converted merchant auxiliary boat (特設特務艇, Tokusetsu tokumutei)	Converted merchant capture-net layer (特設捕獲網艇, Tokusetsu hokakumōtei)
		Converted merchant anti-submarine net layer (特設防潜網艇, Tokusetsu bōsenmōtei)
		Converted merchant mine boat (特設敷設艇, Tokusetsu fusetsutei)
		Converted merchant submarine chaser (特設駆潜艇, Tokusetsu kusentei)
		Converted merchant minesweeper
		Converted merchant picket boat (特設監視艇, Tokusetsu kanshitei)
	Converted merchant auxiliary vessels (特設特務艦船, Tokusetsu tokumukansen)	Converted merchant transport vessel (特設運送艦, Tokusetsu unsōkan)
		Converted merchant transport ship	Munition and ammunition ship
			Water supply ship
			Food supply ship
			Collier
			Oiler
			Collier-oiler (給炭油船, Kyūtan'yusen)
			Communication ship
			Freighter
		Converted merchant repair vessel (特設工作艦, Tokusetsu kōsakukan)
		Converted merchant harbor service vessel (特設港務艦, Tokusetsu kōmukan)
		Converted merchant survey vessel (特設測量艦, Tokusetsu sokuryōkan)
		Converted merchant icebreaker (特設砕氷船, Tokusetsu saihyōsen)
		Converted merchant cable layer
		Converted merchant hospital ship
		Converted merchant salvage ship
		Converted merchant miscellaneous ship (特設雑役船, Tokusetsu zatsuekisen)

See also

• Japanese ship-naming conventions
• List of ships of the Imperial Japanese Navy
• List of Japanese Navy ships and war vessels in World War II

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