Japanese Naval Fleet Building Plans during the Pacific War

Japan's wartime naval building plans will be of interest to any naval historian. The changes that resulted from the disaster at Midway are clearly visible in the altered plan of 1942.

AOW = At Outbreak Of Pacific War

AO = oiler

AP = transport

AUX = auxilliary

BB = battleship

BC = battlecruiser

CA = heavy cruiser

CL = light cruiser

CV = fleet carrier

DD = destroyer

Esc = escort

GB = gunboat

ML = minelayer

MS = minesweeper

MTB = motor torpedo boat

NL = netlayer

PB = patrol boat

Repr = repair

SC = sub chaser

SS = submarine

SS supply = supply submarine

ST = seaplane tender

1941 Emergency Program

Number Planned	Class	Type	Completed	Status AOW
2	Junyo *	CV	2	2 under conversion
2	Ibuki	CA	0	laid down Apr and Jun 42
1	Unryu	CV	1	laid down Aug 42
1	Chihya	ST	0	not proceeded with
4	Khazahaya	AO	2	laid down Sep 41 and Feb 43
14	Etorofu	Esc	14	all laid down in 42 and 43
8	Mikura	Esc	8	1 laid down Oct 42, all others in 43
8	Ukuru	Esc	8	all laid down in 43 and 44
16	Hayanami	DD	8	laid down late 41, 42 and 43
10	Shimotsuki	DD	6	laid down prior to Dec 41
6	I-40	SS	6	all laid down 42
6	i-46	SS	3	laid down late 43 and early 43
12	RO-35	SS	8	laid down late 41 and 42
9	RO-109	SS	9	all laid down 41 and 42
28	No. 25	MS	11	laid down 42 and 43
20	No. 40	SC	19	laid down 42 and 43
14	Ajiro	ML	1	laid down 43
16	No. 7	MS	16	all laid down 41, 42 and 43
100	No. 1	SCAux	100	all laid down 43 and 44
18	No. 10	MTB	8	unknown, maybe building

1941 Additional Program

Number Planned	Class	Type	Completed	Status AOW
1	I-12	SS	1	laid down Nov 43
1	I-13	SS	1	laid down Feb 43
5	I-52	SS	3	laid down 42
7	I-54	SS	3	laid down 42
15	RO-56	SS	1	probably laid down late 41 or early 42
3	I-351	SS supply	1	laid down 43

1942 5th Replacement Program (pre-Midway)

Number Planned	Class	Type	Completed
2	I-9	SS	0
8	I-15	SS	0
4	I-46	SS	0
1	I-400	SS	0
9	RO-35	SS	0
3	I-351	SS supply	0
16	Shimakaze	DD	0
16	Akitsuki	DD	0
4	Shumushu	Esc	0
2	Type A	BC	0
1	Yamato	BB	0
1	Unryu	CV	0
2	Taiho	CV	0
6	3300 ton	ST	0
1	11000 ton	ST	0
5	Type B	CA	0
4	Shokatu	CL	0
1	Wakataka	NL	0
10	No. 19	MS	0
2	Akashi	Repr	0
3	Kazahaya	AO	0
1	Irako	AO	0
1	6800 ton	Icebreaker	0
1	Tsukushi	Survey	0
8	Ajiro	ML	0
2	Nisshin	ST	0
2	Tsurugizaki	SDS	0
1	Hashidate	GB	0
2	Sumida	GB	0
9	No. 13	SC	0
2	Tsugaru	ML	0
10	I-176	SS	0
9	RO-100	SS	0

1942 Modified 5th Replacement Program (post-Midway)

Number Planned	Class	Type	Completed
15	Unryu	CV	2
5	Taiho	CV	0
3	Akitsushima	ST	0
3	Shiko	SDS	0
2	Type B	CA	0
1	Asadori	NL	0
8	Yasmasame	DD	0
23	Yamatsuki	DD	0
6	I-14	SS	1
14	I-54	SS	0
18	improved I-54	SS	0
15	I-52	SS	0
25	improved I-52	SS	0
42	RO-35	SS	0
18	I-400	SS	3
34	Yaku	Esc	12
36	No. 53	MS	0
30	No. 60	SC	3
7	Hayasui	AO	0
8	Takano	AO	0
7	Kiyozaki	Refrigerator Ship	0
1	Kusunii	Supply	0
2	Hario	Supply	0
5	Ohama	Target	1
2	Mikara	Repr	0
1	Miho	Survey	0
1	Esau	Icebreaker	0
12	Arashima	ML	0
18	No. 28	MTB	0

1942 Additional Program

Number Planned	Class	Type	Completed
29	Matsu	DD	18
13	modified Matsu	DD	13
11	I-361	SS supply	11

1943-44 War Program

Number Planned	Class	Type	Completed
100	No. 151	SCAux	100
280	Type B-1	PB	33
132	No. 1	Esc	53
143	No. 2	Esc	63
46	No. 1	AP	21
1	I-372	SS	1
6	I-373	SS	1
73	No. 101	LST	69
60	No. 101	PBAux	0
9	Kamishima	ML	2
2	Minoo	ML	2
20	No. 1	PBAux	0
23	I-201	SS	3
12	HA-101	SS	10
21	Inagi	Esc	6
20	modified Matsu	DD	1
2	Hario	AO	1
2	Inatori	AO	0
79	HA-201	SS	10

1944-45 War Program

Number Planned	Class	Type	Completed
79	Type B	Esc	0
60	Type D	Esc	0
10	HA-201	SS	0
20	No. 151	SC	0
4	No. 1	AP	0
92	I-361	SS	0
11	Kamishima	ML	0
13	Cargo Sub	SS supply	0
168	No. 1	Esc	0
60	No. 2	Esc	0
88	HA-101	SS	0
140	I-373	SS	0
76	I-201	SS	0
40	No. 101	PBAux	0