While IJN worked fast oilers to be fitted refuel equipment just before the Pearl Habor Operation, though IJN war college had studied an air raid of Pearl Harbor in 1936. 1st hokyubutai and 2nd hokyubutai accompanied invading Kido Butai (KB). I list up names and fates of the 7 oilers. The 1st hokubutai consisted of Kyokuto-maru, Kokuyo-maru, Kenyo-maru and Sinkoku-maru. The 2nd hokyubutai consisted of Toho-maru, Toei-maru and Nichiei-maru. They were all sunk in 1944. The Sinkoku-maru was sunk on the Truk Disaster Day.

IJN Fleet Oilers at Pearl Habor Operation

Name	Kanji	Gross[t]	Power[hp]	Speed	Lost date, cause	Location
Nippon Maru	日本丸	9,974	9,773	19.2kt	1944Jan14 Torpedoed	05-02N140-43E
Kenyo Maru	健洋丸	10,024	11,380	20.2kt	1944Jan14 Torpedoed	05-23N141-32E
Toei Maru	東栄丸	10,022	10,986	19.7kt	1944Jan18 Torpedoed	06-19N150-15E
Sinkoku Maru	神国丸	10,020	11,565	19.8kt	1944Feb17 Air bombarded	07-24N151-43E
Toho Maru	東邦丸	9,997	9,903	20.1kt	1944Mar29 Torpedoed	00-00N118-18E
Kokuyo Maru	国洋丸	10,026	11,033	19.6kt	1944Jul30 Torpedoed	06-07N120-00E
Kyokuto Maru	極東丸	10,051	8,693	18.9kt	1944Sep21 Air bombarded	14-35N120-55E

Kawasaki gata Kosoku Gaikou Yusosen

The destroyers of the Pearl Harbor Operation fueld 600 nm far from Hawaii. The KB ran at 24 kt and 28 kt for 5 hr. It flew aircraft at 230 nm away from Pearl Harbor. The KB received aircraft and ran away at 26 kt till sunset. Running at 20 kt for the rest of the day, the destroyers of the KB met the oilers again and fueled. The dash speed of the fleet was limited by aircraft carrier Kaga (1921-1942). The charging time was limited by fuel capacity of the destroyers.
An oiler of IJN supplied oil to 4 destroyers in a day^[1]. If the same oiler supplied them again, the speed of KB would be limited by the speed of oilers.

IJN used 79 oilers of 610 kt in the Pacific War. 71 oilers were lost because of combats. Most of the 71 oilers were not used for fleet oilers but ferrying oil to Japan mainland after the mid of 1944^[2].

Tbl.4 Specifications of wartime merchant tankers 1941, 1943

Type	Gross [t]	dwt [t]	Length	Engine	Power [hp] Economy/Max	Cruising speed	Built number
TL	10,000	15,200	153m	Turbine	8,000/10,500	16.5kt	19
2TL	10,100	-	148m	Turbine	4,000/5,000	13kt	28
TM	5,200	7,000	120m	Turbine	3,600	11.5kt	26
TS	1,010	1,250	60m	Reciprocating	1,050	10kt	5
2TE	870	-	60m	Diesel	330/420	7kt	-
VLCC	-	301,000	330m	Diesel	37,000	15.5kt	-

Ferried oil to Japan [kbbl]

^{Ishi, p197}

Year	1942	1943	1944	1945
Ferried oil	1,052	1,450	498	114

Oil was very important to continue the Pacific War. Ships run feeding crude oil. Aircraft flew feeding gasoline refined from crude oil. Submarines run feeding diesel oil. Japan began the war to get oil in Sumatra. Japan succeeded to occupy oil wells. But US submarines sank a lot of oil tankers. Ferried oil from Sumatra and Borneo decreased 1/3 in 1944, comparing with 1943. Japan could not bring oil in Japan mainland, though Japan launched 10 wartime merchant tankers of TL type, 9 TL and 3 TL in 1943, 1944 and 1945. 3 launched TL in 1945 were not useful any more, because a communication line between Japan and oil fields was shut by US Army AF and USN. looking up these TL tankers, I found Hashidate Maru, Tadotsu Maru, Otakisan Maru and Daikitsu Maru did not sink in the Pacific War. So 18 of 22 type TL tankers were sunk. A site writes that 19 were completed (ref.1)
Japanese wartime standard ship
Tokusetu kyuyu-sen no Syogen
Tokusetu kyuyu-sen
Tokusetsu Kyuyusen

VLCC is a modern oil tanker which ferries crude oil from Middle East to Japan. Japan needed 951 ferries of oil tankers in 2002 Japanese fiscal year.^[4] It meant 2.6 ferries a day. Japanese economy depends on crude oil from Persian Gulf to Japan.

Lost oil tankers of Japan [t]

^{Ishii p.201 Q1;Apr-Jun, Q2;Jul-Sep, Q3;Oct-Dec, Q4;Jan-Mar}

Fiscal year	1941	1942	1943	1944	1945
Q1	-	1,786	29,778	110,954	284,430
Q2	-	1,716	54,551	139,660	40,150
Q3	975	572	75,733	194,741	0
Q4	0	0	227,954	308,751	0
Total	975	7,074	388,016	754,106	324,580

Built oil tankers of Japan [t]

^{Ishii, p201 Q1;Apr-Jun, Q2;Jul-Sep, Q3;Oct-Dec, Q4;Jan-Mar}

Fiscal year	1941	1942	1943	1944	1945
Q1	-	6,086	35,078	115,554	10,330
Q2	-	26,316	94,451	165,840	0
Q3	975	24,572	95,633	178,141	0
Q4	0	140,500	154,754	85,851	0
Total	975	197,474	379,916	555,386	10,330

Transfer tankes into freighters in 1945

^{Goeisen, p402}

Month	Built	Rebuilt for others	Sunk
Jan	82,404	30,000	248,743
Feb	99,642	55,000	41,743
Mar	112,823	15,000	133,325
Apr	33,707	89,000	100,642
May	66,454	71,000	204,327
Jun	22,481	40,000	186,780
Jul	44,337	18,000	208,728
Aug	12,064	30,000	51,882

Japanese people got 1,900 kcal/day for food in 1944. Japan also lost sea lane in the south of China Sea in the end of 1944. Although IJA and IJN comsumed oil in Japan mainland, So Government began to rebuild oil tankers into freighters for food etc.

Oil tankers shipbuilt of concrete
Ministry of Transportation of Japan planned Kai-E type small oil tankers(880t gross) of concrete. Takechi Shipbuilding Yard launched 1st, 2nd and 3rd Takechimaru. The first Takechimaru was lauunched on Mar 1944. They ran domestic sea of Japan mainly.
Takechi maru

Pipeline route

Piping
The planning pipline needed some materials such as lead of 24t, steel tape of 7.5t, steel wire of 15t per mile. The total lenght was 1600km. US made 30% of the pipes.

One route was starting from Dungeness of UK to Wesel across the Rhine. The length of the pipeline was 700km. There were 19 staions. The other was starting Wight to Rouen in France and the length was 230km. There were 15 stations. Flow rate was 1 million gal per day in 1944. There were 3 staions in Anto and also 3 stations in Rouen. UK built the pipeline 10km per hour on land.

Pipe specifications

ID	OD	weight	liner1	liner2	liner3	liner4
3in(7.6cm)	4.5in(11.4cm)	46.5t/mi	2 laminars paper tape	silk tape soaked asphalt	4 laminar steel tape hemp fiber, steel wire	2 laminar fiber soaked tar

On coast	On frame

Gunzo, p98-103 No.91
Operation Pluto

Remark
1 million gal is equivalent 4,550 kL. So 1 million gal/day is 52.5 L/s. Area of 3in diameter is 45.6cm2. So average flow speed is 5.8 m/s for 2 routes. The value is incredible high. The total length of 2 routes is 930km. As UK prepared pipes of 1600km length, 670km remained. Did UK build other pipelines to improve small flow rate? Or did oil tankers supply 3 stations of Antwerp directly?

Pipes of 10km length weighs 285t. How could corps of engineers transport the weight and build the pipeline on hills or something for an hour?

Japan imported oil of 244,666kL in 2006, equivalent to 670kL/day. Japan consumed gasoline of 82,208kL in 2007 therefore 225kL daily. Allied armis in Europe theater consumed 20 folds of Japan now, did'nt they? Allied armies transported 19,000t daily on Aug 1944. So the pipelines carried 1/4 weight of all the loads. I suppose US war strategy was limited by gasolie supply mainly.
Keizai sangyo syo tokutei gyosyu sekiyu tou syohi toukei
Kyo no Sekiyu Sangyo
Creveld p366

By the way, How many tankers needed to transport 4,550kL/day across the Atlantic? Size of US wartime T2 tanker was 10,100t. I suppose the tanker could ferried 10,100x1.6=16,160kL. Therefore a T2 tanker had to arrive at UK in 3 or 4 per day. For example, distance between Halifax(44.6N, 63.6W) at Canada and North Strait(56N, 10W) of Scotland and Ireland is 3,900km. If speed of a convoy were 7kt, it needed the voyage of 13 days. Each convoy needed 3 or 4 oil tankers to ferry equivalent to 16,000kL/day at least. The return empty tankers also needed. As for building T2 type tanker, US built 381 during WWII. If Germany thought gasoline transport deep, Germany was not to war against Russia.

[1] Nakajima, p184
[2] Senji, p156
[3] VLCC for 日本
[4] イラストで表すエネルギー資源が届くまで

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