Oiler
Desperate War of Japan in the Pacific
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RN experimented refueling at sea in 1905. USN studied the logistics to invade Japan. US called it orange plan. USS Maumee (AO-2) fueled warships at sea in 1917. It could fuel 100 to 150kL per hour. It was to be stationed at sea. Speed was 14kt.
Logistics hattatu-si

 Fleet oiler
Originally IJN had planned intercepting USN fleet near Saipan before the Pacific war. Therefore IJN had not drilled fueling eager. On the contrary to IJN, USN had studied refueling from Hawaii to Guam. The Great White Fleet ran fueling coal, when it came to Japan. It was almost impossible to refuel a lot of coal while running in those days. But oil changed the sea battle.

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
NameKanjiGross[t]Power[hp]SpeedLost date, causeLocation
Nippon Maruܴ9,9749,77319.2kt1944Jan14 Torpedoed05-02N140-43E
Kenyo Maruδ10,02411,38020.2kt1944Jan14 Torpedoed05-23N141-32E
Toei Maruɴ10,02210,98619.7kt1944Jan18 Torpedoed06-19N150-15E
Sinkoku Maru10,02011,56519.8kt1944Feb17 Air bombarded07-24N151-43E
Toho Maruˮ9,9979,90320.1kt1944Mar29 Torpedoed00-00N118-18E
Kokuyo Maruδ10,02611,03319.6kt1944Jul30 Torpedoed06-07N120-00E
Kyokuto Maru10,0518,69318.9kt1944Sep21 Air bombarded14-35N120-55E
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].

 Oil tanker
The Pacific War was the battle whether Japan or US controlled airfields of isolated islands in the Pacific Ocean. So one of the most stratgic materials was aviation gasoline. Tbl.4 shows wartime merchant tankers of Japan in 1941. Japan began to build simplified merchant ships because of shortage of merchant ships in 1943. As for tankers, Japan built 28 of type 2TL, 34 of type 2TM and 135.
Ouchi, p80
Gunzo, p17, No61
Senji Hyoujyun-sen Gaisetu ref.1

Tbl.4 Specifications of wartime merchant tankers 1941, 1943
TypeGross [t]dwt [t]LengthEnginePower [hp]
Economy/Max
Cruising
speed
Built
number
TL10,00015,200 153mTurbine8,000/10,50016.5kt19
2TL10,100- 148mTurbine4,000/5,00013kt28
TM5,2007,000 120mTurbine3,60011.5kt26
TS1,0101,250 60mReciprocating1,05010kt5
2TE870- 60mDiesel330/4207kt-
VLCC-301,000 330mDiesel37,00015.5kt-

Ferried oil to Japan [kbbl] Ishi, p197
Year1942194319441945
Ferried oil1,0521,450498114
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 year19411942194319441945
Q1-1,786 29,778110,954284,430
Q2-1,716 54,551139,66040,150
Q3975572 75,733194,7410
Q400 227,954308,7510
Total9757,074 388,016754,106324,580

Built oil tankers of Japan [t] Ishii, p201 Q1;Apr-Jun, Q2;Jul-Sep, Q3;Oct-Dec, Q4;Jan-Mar
Fiscal year19411942194319441945
Q1-6,086 35,078115,55410,330
Q2-26,316 94,451165,8400
Q397524,572 95,633178,1410
Q40140,500 154,75485,8510
Total975197,474 379,916555,38610,330

Transfer tankes into freighters in 1945 Goeisen, p402
MonthBuiltRebuilt for othersSunk
Jan82,40430,000248,743
Feb99,64255,00041,743
Mar112,82315,000133,325
Apr33,70789,000100,642
May66,45471,000204,327
Jun22,48140,000186,780
Jul44,33718,000208,728
Aug12,06430,00051,882
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

 Pluto Operation -Pipeline across the English Channel
Coast
Pipeline route
Pluto Operation is the code name of Pipeline. The pipeline was built under the Enlgish Channel. Hirota reported the plan.

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
IDODweightliner1liner2liner3liner4
3in(7.6cm)4.5in(11.4cm)46.5t/mi2 laminars paper tapesilk tape soaked asphalt4 laminar steel tape
hemp fiber, steel wire
2 laminar fiber soaked tar

CoastBridge
On coastOn 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
[4] 饹Ȥɽͥ륮񸻤Ϥޤ


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