ZATSUYOSEN!

(SEIKYO MARU prewar)

IJN SEIKYO MARU:
Tabular Record of Movement


© 2011-2020 Gilbert Casse, Bob Hackett and Peter Cundall

Revision 1

5 May 1934:
Uraga. Laid down by Uraga Senkyo K.K. Kojo shipyard as a 2,606-ton cargo ship for Chosen Yusen K.K., Jinsen.

20 September 1934:
Launched and named SEIKYO MARU. [1]

15 December 1934:
Completed. Her registered port is Jinsen, Chosen (now Incheon, South Korea). Her gross registered tonnage (GRT) and net registered tonnage (NRT) are 2,606-tons and 1,527-tons respectively. Her call sign is JESG. [2]

July 1937: The Marco Polo Bridge (The"First China Incident") Incident:
Hun River. Japanese troops fire blank cartridges during night maneuvers at the Marco Polo Bridge. Chinese troops across the river fire back, but do not cause injuries. At morning roll call, the Japanese discover a soldier missing and assume the Chinese have captured him. The Japanese demand entry to the Beijing suburb of Wanping to look for the soldier, but the Chinese refuse. The Japanese shell the city and an undeclared war on China begins.

E 1937:
SEIKYO MARU is requisitioned by the Imperial Army. Her gross registered tonnage and net registered tonnage are changed to 2,608-tons and 1,532-tons respectively. Her registered port is changed to Rashin, Chosen (formerly Rajin, also known as Rason, now Najin, North Korea). [2]

E 1938:
Released to her owners. Calls at Tokyo ~ Yokohama ~ Busan, Chosen (now Pusan, South Korea) ~ various N Korea east coast’s ports ~ Yuki, Chosen (also known as Unggi, now Sonbong, North Korea). Her registered port changes again to Jinsen.

26 March 1939:
Arrives at Humen, Pearl River estuary, southern China, near Canton.

29 March 1939:
Departs Humen and returns later this day.

9 April 1939:
Departs Humen, southern China, near Canton.

18 October 1940:
Requisitioned by the IJN as a transport (Ippan Choyosen). [3]

1 November 1940:
Registered in the IJN under internal order No. 770 and attached to the Sasebo Naval District as an auxiliary gunboat and minelayer. Her home port is Sasebo. LtCdr Morimoto Shinichi is appointed Commanding Officer.

5 November 1940:
Navy (Resv) LtCdr Yagi Katsuji is appointed Commanding Officer.

7 November 1940:
Tama. The conversion to an auxiliary gunboat is completed at Tama Zosensho K.K. shipyard.

15 November 1940:
Rerated an auxiliary gunboat under internal order No. 830. Attached to the 1st Gunboat Division under Ordinance No. 837.

27 December 1940:
Attached as 13th Gunboat under Navy secret instruction No. 47.

15 January 1941:
Assigned to minelaying operations as an auxiliary gunboat engaged in minelaying under internal order No. 56.

23 March 1941:
Departs Tokuyama, Yamaguchi Prefecture.

E March-April 1941:
Operates in Korea waters.

4 April 1941:
Arrives at Karatsu, Saga Prefecture, Kyushu.

10 June 1941:
Departs Sasebo.

E June-July 1941:
Operates in southern China waters.

8 July 1941:
Arrives at Mako, Pescadores (now Magong, Penghu Islands, Taiwan).

17 July 1941:
Departs Mako.

E July-August 1941:
Operates in southern China waters.

10 September 1941:
Arrives at Sasebo.

1 October 1941:
Capt. Tomita Kenshiro is appointed Commanding Officer.

15 October 1941:
Detached from the 1st Gunboat Division under internal order No. 1250. Attached to Chinkai Guard District, Rashin Base Force.

29 October 1941:
Departs Yushin, Chosen’s east coast (now Sokcho, South Korea).

20 November 1941:
Attached to Chinkai District in Vice Admiral Sukigara Tamazo’s (37)(former CO of BB KONGO) Rashin Base Force also consisting of auxiliary gunboat HAKKAI MARU.

7 December 1941:
Remains attached to Chinkai District, Rashin Base Force under Navy secret instruction No. 12.

19 December 1941:
Remains attached to Chinkai District, Rashin Base Force under Navy secret instruction No. 22.

31 December 1941:
Remains attached to Chinkai District, Rashin Base Force under Navy secret instruction No. 28.

13 January 1942:
Fitting of an external degaussing coil is started.

15 January 1942:
Remains attached to Chinkai District, Rashin Base Force under Navy secret instruction No. 32.

19 January 1942:
The fitting is completed.

30 January 1942:
Chinkai. Docks Chosen Heavy Industries K.K shipyard.

4 February 1942:
Undocked.

10 February 1942:
Remains attached to Chinkai District, Rashin Base Force under Navy secret instruction No. 41. Departs Chinkai.

E February 1942:
Calls at Sasebo. Departs later for Chinkai.

16 February 1942:
Arrives at Chinkai.

20 February 1942:
An improved version of external degaussing coil with magnetic field measuring equipment is completed.

E February 1942:
Departs Chinkai.

28 February 1942:
Arrives at Rashin.

20 May 1942:
Remains attached to Chinkai District, Rashin Base Force.

20 June 1942:
Departs Chinkai.

E July-August 1942:
Calls at Gensan Chosen (now Wonsan, North Korea)and Rashin (Chosen).

14 August 1942:
Arrives at Chinkai.

E 14-15 August 1942:
Loads 6-tons of ammunition and embarks 91 Navy personnel.

15 August 1942:
Departs Chinkai.

E 17 August 1942:
Arrives at Sasebo and lands troops and ammunition. Probably loads ammunition and embarks troops. Departs later for Chinkai.

19 August 1942:
Arrives at Chinkai.

E 20-23 August 1942:
Unloads 119-tons of ammunition and disembarks 248 troops.

24 August 1942:
Departs Chinkai.

25 August 1942:
Removed from the auxiliary gunboat list under internal order No. 1581. That same day, re-registered in the IJN under internal order No. 1582 and attached to the Sasebo Naval District as an auxiliary transport (Otsu category). Her home port is Sasebo. Capt. Tomita Kenshiro is attached to the Sasebo Naval district. [4]

E August-September 1942:
Calls at Gensan and Rashin.

2 September 1942:
Receives transfer order.

7 September 1942:
Together with auxiliary gunboat RYOTOKU MARU scheduled to undergo conversion to a miscellaneous auxiliary transport (Otsu) category at the Sasebo Naval Yard under Navy’s secret instruction No. 11261. [4]

8 September 1942:
Arrives at Sasebo. Begins scheduled conversion at the Sasebo Naval Yard.

11 September 1942:
Transferred by changing the type [category]. Navy (Resv) LtCdr. Shimao Junichi is appointed Commanding Officer.

6 October 1942:
The conversion is completed. Departs Sasebo for Chinkai.

8 October 1942:
Arrives at Chinkai.

10 October 1942:
Departs Chinkai for Chinnampo, Chosen (now North Korea).

13 October 1942:
Arrives at Chinnampo.

18 October 1942:
Departs Chinnampo.

23 October 1942:
South entrance of Kii Straits. LtCdr (later Vice Admiral) Vernon L. Lowrance’s (USNA’30) USS KINGFISH (SS-234) sights a transport. At 1500, Lowrance torpedoes and hits SEIKYO MARU at 33-12N, 135-14E. Her deck awash, SEIKYO MARU sinks rapidly taking down 43 men.

30 November 1942:
Removed from the Navy List under internal order No. 2198.

Authors Notes:
[1] Not to be confused with Toa Kaiun K.K. (2565 GRT, ’21)

[2] 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.

[3] See Zatsuyosen home page for full explanation.

[4] 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 and Berend van der Wal of Netherlands.

Photo credit goes to Erich Muehlthaler of Germany.

-Gilbert Casse, Bob Hackett and Peter Cundall

Back to IJN Transports Page