KYURYOSEN!

(UNYO MARU No. 3, sistership of UNKAI MARU No. 3, prewar)

IJN UNKAI MARU No. 3:
Tabular Record of Movement


© 2017 Gilbert Casse, Berend van der Wal and Peter Cundall


9 August 1918:
Yokohama. Laid down by Yokohama Dock K.K shipyard for Hashimoto Kisen K.K. as a cargo ship.

25 December 1918:
Launched and named KAZAN MARU.

31 January 1919:
Completed and registered at Yokohama with a Gross Registered Tonnage (GRT) and Net Registered Tonnage (NRT) respectively of 2,969-tons and 1,841-tons. [1]

1921:
Her GRT and NRT are respectively changed to 2,989-tons and 1,855-tons. [1]

1922:
Her ownership is changed to Nakamura Seishichiro and registered port to Tarumi, Hyogo prefecture.

19 December 1930:
Her ownership is changed to Nakamura Gumi K.K. and registered port to Hiroshima.

11 February 1931:
Renamed UNKAI MARU No. 3.

2 June ~ 9 September 1931:
Chartered by Nichiro Gyogyo K.K.

17 May ~ 12 September 1932:
Chartered by Nichiro Gyogyo K.K.

1933:
Her GRT and NRT are respectively changed to 3,014-tons and 1,884-tons. [1]

5 March 1933:
Arrives at Manila, Philippines.

6 March 1933:
Departs Manila.

27 June ~ 28 September 1933:
Chartered by Nichiro Gyogyo K.K.

28 May ~ 17 September 1935:
Chartered by Nichiro Gyogyo K.K.

1 October 1935:
Her ownership is changed to Nakamura Kisen K.K.

21 May ~ 29 September 1936:
Chartered by Nichiro Gyogyo K.K.

27 May ~ 30 September 1937:
Chartered by Nichiro Gyogyo K.K.

7 June ~ 27 September 1938:
Chartered by Nichiro Gyogyo K.K.

4 May ~ 19 September 1939:
Chartered by Nichiro Gyogyo K.K.

1939:
Her GRT and NRT are respectively changed to 3,023-tons and 1,870-tons. [1]

1941:
Her registered port is changed to Kobe.

15 April 1942:
Registered as an auxiliary stores ship attached to the Yokosuka Naval District under instruction No. 701.

16 April 1942:
Scheduled to enter the Yokosuka Naval yard for conversion to military duty under Navy’s secret instruction No. 4575.

18 April 1942:
Formerly requisitioned by the IJN.

April 1942:
Registered as an auxiliary stores ship (Otsu) category attached to the Yokosuka Naval District. [2]

1 May 1942:
Graduated as a supply unit under Yokosuka Naval District instruction No. 78.

15 May 1942:
The conversion is completed. Assigned to food transport missions under instruction No. 177. Departs Yokosuka that same day on her first mission with cargo-passenger ship SHIBAZONO MARU escorted part way by auxiliary minelayer TAKACHIHO MARU.

20 May 1942:
Arrives at Minami Tori Jima (Marcus Island), Ogasawara Gunto (Bonins) and departs later this day.

24 May 1942:
Arrives at Ootori Jima (Wake Island) and departs later that day.

27 May 1942:
Arrives at Eniwetok, Marshalls and departs later in the day.

29 May 1942:
Arrives at Kwajalein, Marshalls. Comes alongside auxiliary gunboat IKUTA MARU and replenishes her with food.

31 May 1942:
Departs Kwajalein.

1 June 1942:
Arrives at Roi, Marshalls.

2 June 1942:
Departs Roi.

3 June 1942:
Arrives at Wotje, Marshalls.

4 June 1942:
Departs Wotje and arrives at Taroa, Maloelap, Marshalls later that day.

5 June 1942:
Departs Taroa.

6 June 1942:
Arrives at Majuro, Marshalls and departs later this day.

7 June 1942:
Arrives at Mille, Marshalls and departs later that same day.

8 June 1942:
Arrives at Imieji, Jaluit, Marshalls.

9 June 1942:
Departs Imieji and arrives at Jaluit later this day.

10 June 1942:
Departs Jaluit.

11 June 1942:
Arrives at Makin, Gilberts and departs later that day.

13 June 1942:
Arrives at Jaluit.

14 June 1942:
Departs Jaluit.

15 June 1942:
Graduated as a supply unit under Yokosuka Naval District instruction No. 99.

19 June 1942:
Arrives at Truk, Central Carolines.

29 June 1942:
Departs Truk.

5 July 1942:
Arrives at Yokosuka.

17 July 1942:
Departs Yokosuka on her second mission with transport IWASHIRO MARU, apparently without escort.

24 July 1942:
Arrives at Minami Tori Jima and departs later this day.

28 July 1942:
Arrives at Ootori Jima.

29 July 1942:
Departs Ootori Jima.

1 August 1942:
Arrives at Eniwetok.

2 August 1942:
Departs Eniwetok.

4 August 1942:
Arrives at Kwajalein.

7 August 1942:
Departs Kwajalein and anchors off Roi. Departs there and arrives at Roi later that day.

9 August 1942:
Departs Roi.

10 August 1942:
Arrives at Wotje.

11 August 1942:
Departs Wotje.

12 August 1942:
Arrives at Taroa.

13 August 1942:
Departs Taroa.

14 August 1942:
Arrives at Majuro and departs later this day.

15 August 1942:
Arrives at Mille.

16 August 1942:
Departs Mille.

17 August 1942:
Arrives at Imieji.

18 August 1942:
Departs Imieji and arrives at Jaluit later that day.

22 August 1942:
Departs Jaluit.

23 August 1942:
Arrives at Kwajalein and departs for Japan later this day.

3 September 1942:
Arrives at Yokosuka.

10 September 1942:
Scheduled to a third mission under secret instruction No. 42.

14 September 1942:
Departs Yokosuka on her third mission.

20 September 1942:
Arrives at Minami Tori Jima and departs later that day.

25 September 1942:
Arrives at Ootori Jima. Assigned that same day to troops supply mission under Yokosuka Naval District instruction No. 126.

26 September 1942:
Departs Ootori Jima.

30 September 1942:
Arrives at Kwajalein.

2 October 1942:
Departs Kwajalein and arrives at Roi later this day.

3 October 1942:
Departs Roi and arrives at Kwajalein later that day.

6 October 1942:
Departs Kwajalein.

7 October 1942:
Arrives at Wotje and departs later this day.

8 October 1942:
Arrives at Taroa.

9 October 1942:
Departs Taroa.

10 October 1942:
Arrives at Mille.

11 October 1942:
Departs Mille.

12 October 1942:
Arrives at Imieji. Departs there and arrives at Jaluit later that same day.

14 October 1942:
Departs Jaluit.

15 October 1942:
Arrives at Makin.

16 October 1942:
Departs Makin.

17 October 1942:
Arrives at Taroa.

20 October 1942:
Departs Taroa.

22 October 1942:
Arrives at Ocean (now Banaba) Island and departs later this day.

23 October 1942:
Arrives at Nauru Island and departs later that day for Japan.

6 November 1942:
Arrives at Yokosuka.

29 November 1942:
Transfers from Yokosuka to Yokohama.

30 November 1942:
At Yokohama quay No. 7. Also occupying the quay is the German auxiliary cruiser THOR berthed alongside the German supply tanker UCKERMARK with the prize ship LEUTHEN (ex-NANKIN) berthed nearby. THOR is being refurbished for another raider cruise (her planned third) and UCKERMARK is undergoing tank cleaning by Chinese laborers. Shortly before 1400, an enormous explosion rocks UCKERMARK and soon after, a bigger explosion wrecks the tanker and throws part of her bridge onto THOR and onto the wharf. The resulting fire and explosions destroy THOR, UCKERMARK, LEUTHEN and UNKAI MARU No. 3 as well as some harbor craft. Flaming oil spreads across the harbor. 13 crewmen on THOR, 53 on UCKERMARK, one crewman on UNKAI MARU No. 3 and an unknown number of Japanese and Chinese are killed. The exact cause is unknown but presumed to be a tank explosion on UCKERMARK.

1 July 1943:
Removed from the Navy list under instruction No. 1321.


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 Kyuryosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.

Thanks go to Gengoro S. Toda of Japan.

- Berend van der Wal, Gilbert Casse and Peter Cundall.


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