YUSOSEN!



(Wartime Standard Merchant Tanker 1TL)

IJN SEIYO MARU:

Tabular Record of Movement

© 2005-2020 Bob Hackett and Peter Cundall.

Revision 3


24 July 1943:
Nagasaki. Laid down at down at Mitsubishi Jukogyo K.K. Nagasaki Zosensho as a 10,536-ton Standard Merchant 1TL Tanker for Kokuyo Kisen K.K.

11 November 1943:
Launched and named SEIYO MARU.

8 December 1943:
Added to the Naval list under instruction No. 422.

15 January 1944:
Completed and registered at Tokyo. Her Gross Registered Tonnage (GRT) and Net Registered Tonnage (NRT) respectively are 10,536-tons and 6,278-tons. Her call sign is JOPT. [1]

January 1944:
Requisitioned by the IJN as a naval transport ship.

10 February 1944:
Designated the 32nd. naval ship.

16 February 1944:
SEIYO MARU likely departs Moji in convoy HI-45 also consisting of transports TAMATSU and ARIMASAN MARUs and tankers OMUROSAN, ITSUKUSHIMA, KUROSHIO and TATEKAWA MARUs escorted by destroyer SHIOKAZE.

20 February 1944:
SHIOKAZE detaches from the convoy.

21 February 1944:
KUROSHIO MARU develops engine trouble and is detached for Takao.

22 February 1944:
Kaibokan MIYAKE joins the convoy.

23 February 1944:
TAMATSU MARU is detached from the convoy and heads for Manila. SHIOKAZE rejoins as an escort.

27 February 1944:
At 1645, arrives at Singapore.

11 March 1944:
At 0730, convoy HI-48 departs Singapore consisting of tankers SEIYO, ITSUKUSHIMA, OMUROSAN, OTOWASAN, TATEKAWA, ITSUKUSHIMA, NICHIEI and KUROSHIO MARUs, transport/cargo liners AWA, SANUKI, TEIA and HOKUROKU MARUs and two unidentified ships escorted by kaibokan MIYAKE, SHIMUSHU, IKI and ETOROFU and later arrives at Van Phong Bay, French Indochina (also known as Port Dayot, now Vietnam).

15 March 1944:
Departs Van Phong Bay.

17 March 1944:
Her engine fails twice.

19 March 1944:
At 1600, arrives at Takao.

20 March 1944:
At 1300, departs Takao. Released to her owners. Requisitioned again that same day by the IJN and registered in the Yokosuka Naval District as an auxiliary transport (oil supply) under order No. 465. Assigned to the Combined Fleet as an auxiliary transport Otsu category. [2]

Navy (Resv) unknown rank, Kawano Masami is apppointed Commanding Officer.

At 1300, departs Takao.

25 March 1944:
At 0500, arrives at Moji.

6 April 1944:
Departs Yokosuka. Later that day, arrives at Tateyama.

7 April 1944:
At 0330, SEIYO MARU departs Tateyama in convoy Higashi-Matsu No. 5 (outbound) consisting of transports ASOSAN, NOTO, TOSAN and MIIKE MARUs escorted by destroyer SATSUKI and kaibokan MANJU and KASADO and CD-4.

10 April 1944:
Arrives at Futami, Chichijima.

18 April 1944:
Departs Futami.

24 April 1944:
Arrives at Palau.

30 April 1944:
Departs Palau in convoy also consisting of SHINROKU and SHINSEI MARUs escorted by destroyer YUZUKI and kaibokan MANJU.

2 May 1944:
MANJU attacks an enemy submarine and claims a kill. Later the same day SHINROKU and SHINSEI MARUs arrive at Davao.

4 May 1944:
Arrives at Balikpapan, Borneo, Netherlands East Indies (Now Kalimantan, Indonesia).

5 May 1944:
Attached to the Combined Fleet First Mobile Fleet under wireless instruction No. 75.

9 May 1944:
Rerated as an auxiliary transport ship Ko category. [2]

12 May 1944:
Departs Balikpapan.

14 May 1944:
Arrives at Tawi Tawi, Philippines.

16 May 1944:
At 1300 lies next to starboard side of fleet oiler TSURUMI and begins transfering 3,450-ton of heavy oil to TSURUMI. At 1620 completes transfering heavy oil to TSURUMI.

17 May 1944:
At 0430 Departs from side of TSURUMI. Departs Tawi Tawi. Later that day, arrives at Tarakan, Borneo, Netherlands East Indies (now Kalimantan, Indonesia).

19 May 1944:
At 1900 departs Tarakan escorted by destroyers of 4 DesDiv.

20 May 1944:
Arrives at Tawi Tawi.

23 May 1944:
At 0640, SEIYO MARU departs Tawi Tawi in a convoy consisting of tankers KOKUYO, TATEKAWA and NICHIEI MARUs escorted by destroyers HIBIKI, AKISHIMO and HAMAKAZE.

24 May 1944:
Off Mindanao. At 1517, LtCdr Charles H. Andrews' USS GURNARD torpedoes and sinks TATEKAWA MARU at 05-42N, 125-43E.

25 May 1944:
At 0200, arrives at Davao.

13 June 1944: Operation “A-GO” - The Defense of the Marianas:
Tokyo. The CINC, Combined Fleet, Admiral Toyoda Soemu, (former CO of HYUGA), activates A-GO.

Davao. That same day, battleship FUSO transfers most of her fuel oil to the 1st Supply Force's oilers SEIYO, KOKUYO and NICHIEI MARUs and HAYASUI. Rated as an Operation A-GO First Supply Unit.

14 June 1944:
Departs Davao towards the Philippine Sea refueling point with the 1st Supply Force and destroyers HATSUSHIMO, SHIRATSUYU and second-class destroyer TSUGA.

15 June 1944:
90 mile SE of Surigao Strait. SEIYO MARU collides with destroyer SHIRATSUYU and shears off her stern. As she sinks, SHIRATSUYU’s depth-charges explode among survivors in the water. 104 crewmen are killed.

16 June 1944:
At about 1000, the 1st Supply Force's oilers HAYUSUI and NICHIEI, KOKUYO and SEIYO MARUs rendezvous at 11-00N, 130-00E with Vice Admiral Ugaki Matome's (former CO of HYUGA) aborted Operation "Kon" Task Force's Bat Div 1's YAMATO, and MUSASHI, Cru Div 5's HAGURO and MYOKO, DesRon 2's light cruiser NOSHIRO and Des Div 4's OKINAMI, SHIMAKAZE, ASAGUMO, MAIKAZE and MICHISHIO and DesRon 10's YAMAGUMO and NOWAKI.

Ugaki's force is refueled promptly, then his force and the 1st Supply Force head north to join Vice Admiral Ozawa Jisaburo's (former CO of HARUNA) First Mobile Fleet's Main Body. At 1650, they rendezvous with Ozawa. The 1st Supply Force begins to refuel the Mobile Fleet.

17 June 1944:
At 2000, the refueling is completed. At this time, the First Mobile Fleet is at 12-15N, 132-45E. SEIYO MARU refuels destroyers of 27 DesDiv amongst others. The 1st Supply Force stands by to rendezvous with the 2nd Supply Force's oilers GENYO and AZUSA MARUs enroute from Guimaras. All six oilers then depart the area for a designated standby point at 14-40N, 134-20E.

20 June 1944: - The Battle of the Philippine Sea:
The Supply Forces are attacked by LtCdr J. D. Blitch's seven Grumman "Avenger" TBF torpedo-bombers, 12 Curtiss "Helldiver" SB2C dive-bombers and 16 "Hellcat" F-6F strafers from Task Force 58's USS WASP (CV-18). SEIYO MARU is hit by 2 bombs in the third oil tank and set afire. Three crewmen are killed. HAYASUI is hit by a bomb and set afire. The 2nd Supply Force's oiler GENYO MARU is damaged by bombs and later at 1930 scuttled by destroyer UZUKI.

Later at 1830, destroyer YUKIKAZE removes SEIYO MARU's crew and scuttles her with a torpedo.

10 August 1944:
Removed from the Navy List.


Authors' Notes:
[1] NRT is a ship's cargo volume capacity expressed in "register tons", one of which equals to a volume of 100 cubic feet (2.83 m3). It is calculated by subtracting non-revenue-earning spaces i.e. spaces not available for carrying cargo, for example engine rooms, fuel tanks and crew quarters, from the ship's gross register tonnage (GRT). Net register tonnage (NRT) is not a measure of the weight of the ship or its cargo, and should not be confused with terms such as deadweight tonnage or displacement.

[2] There were two categories of Yusosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

Thanks for assistance goes to Allan Alsleben of Oregon, USA, Mr. Berend van der Wal of Netherlands and Mr. Gilbert Casse of France. Thanks go to Gengoro S. Toda of Japan.

- Bob Hackett and Peter Cundall.


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