ZATSUYOSEN!

(SHOAN MARUU prewar)

IJN SHOAN MARU:
Tabular Record of Movement


© 2011 Gilbert Casse, Bob Hackett and Peter Cundall

10 July 1937:
Tama. Laid down by Tama K.K. Zosensho shipyard as a 5,624-ton cargo ship for Matsuoka Kisen K.K., Seido.

21 October 1937:
Launched and named SHOAN MARU.

30 November 1937:
Completed. Her registered port is Seido, near Osaka. Her GRT and net registered tonnage are 5,619-tons and 3,336-tons respectively.

E 1938:
Her GRT and net registered tonnage are changed to 5,624-tons and 3,331-tons respectively.

E 1941:
Her home port is changed to Ashiya, near Osaka.

5 September 1941:
Starts conversion to her military duty.

12 September 1941:
Requisitioned by the IJN as a transport (Ippan Choyosen). [1]

20 September 1941:
Registered in the IJN as an auxiliary transport under internal order No. 1093 and attached to the Kure Naval District as an auxiliary transport, (Otsu) category. Her home port is Kure. [2]

14 October 1941:
The conversion is completed.

10 April 1942:
Removed from the Navy List under internal order No. 662. SHOAN MARU is requisitioned as a Navy transport (Ippan Choyosen). [1]

24 April 1942:
Arrives at Kirun, Formosa (now Keelung, Taiwan).

25 April 1942:
Departs Kirun.

05 May 1942:
Arrives at Tsukumi, Oita Prefecture, Kyushu.

11 May 1942:
Departs Tsukumi.

6 July 1942:
Arrives at Yokohama.

E July 1942:
Arrives at Yokosuka.

15 July 1942:
Departs Yokosuka.

24 July 1942:
Transits the Bungo Suido (Straits) with tanker TOHO MARU. Later that same day, arrives at Tsukumi.

25 July 1942:
Departs Tsukumi.

26 November 1942:
Arrives at Yokosuka.

2 December 1942:
Departs Yokosuka and arrives that same day at Tokyo. Transfers later to Shibaura, Tokyo.

3 December 1942:
Arrives at Shibaura.

10 December 1942:
At 1000, departs Shibaura for Kwajalein, Marshalls with auxiliary transport SHOHEI MARU carrying between them 1700 men of the 1st Pioneer Corps, escorted by auxiliary minesweepers SHONAN MARU No. 3 and TAMA MARU No. 3.

19 December 1942:
At 1200, the convoy meets up with destroyer ASANAGI near Jaluit, Marshalls.

20 December 1942:
Arrives at Kwajalein. Departs later still with SHOHEI MARU, for Tarawa, Gilberts.

23 December 1942:
Arrives at Tarawa. Disembarks all troops and related supplies and equipment. Both ships depart later to Kwajalein.

26 December 1942:
At 0500, both SHOAN MARU and SHOHEI MARU arrive back at Kwajalein. Later they make further trips to Tarawa.

2 January 1943:
Departs Tarawa.

16 January 1943:
Arrives at Ponape, Carolines.

25 January 1943:
Departs Ponape for Japan.

26 January 1943:
About 500 nms E of Saipan, Marianas, evening time. LtCdr John B. Azer’s (USNA ’28) USS WHALE (SS-239) sights the smoke of a steamer about 16 nms on her starboard bow. Azer closes the range and launchs one torpedo. A dull thud is heard throughout the boat, but no explosion occurs. WHALE keeps tracking SHOAN MARU during the night.

27 January 1943:
About 400 nms E of Saipan, in the morning. Azer fires three more torpedos but fails to score any hits. A fourth torpedo also fails to explode and SHOAN MARU turns away from the submarine, presenting only her stern to view. Azer attacks again with a fifth and sixth torpedoes, the latter passes directly below the transport’s stern and must have run under its full length without detonating. SHOAN MARU then begins dropping depth charges without conclusive results.

At 1400, Azer fires the seventh and last remaining torpedo which hits SHOAN MARU at 14-24N, 153-30E, just abaft her stack, causing her to lose power. SHOAN MARU settles but does not sink. Later, she is towed at a mere six knots speed to Saipan for repairs.

30 January 1943:
Auxiliary gunboat EDO MARU meets up with damaged SHOAN MARU. Later that day they both arrive at Saipan. SHOAN MARU undergoes emergency repairs and water drainage to keep her afloat.

E 1943:
Extensive repairs are carried out to her hull, bridge and crew accommodation, albeit slowly due to materials shortage. The ship remains anchored off Garapan.

14 January 1944:
Bombed and damaged in an air attack. One crewman is killed.

23 February 1944:
SHOAN MARU sustains an airstrike from USS ESSEX (CV-9)’s and USS YORKTOWN (CV-10)’s aircraft and is further damaged beyond repairs. The ship is either sunk at this point or later during the Jun ‘44 invasion of Saipan.

30 May 1944:
Removed from the transport (Ippan Choyosen) list.

Postwar:
SHOAN MARU's wreck becomes a recognized recreational dive site.

Authors Notes:
[1] See Zatsuyosen home page for full explanation.
[2] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

Thanks go to Gengoro S. Toda of Japan.

-Gilbert Casse, Bob Hackett and Peter Cundall

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