Japanese Transports

ZATSUYOSEN!

(HIROTAMA MARU, prewar)

IJN HIROTAMA MARU:
Tabular Record of Movement

© 2012-2023 Gilbert Casse, Bob Hackett and Peter Cundall
Revision 1

E 1939:
Koyagijima. Laid down by Kawaminami Kogyo K.K. Zosensho shipyard for Tamai Shosen K.K. as a 1,911-ton cargo ship, part of the Peacetime Standard Ship (D) Type Program.
18 July 1939:
Launched and named HIROTAMA MARU.
26 December 1939:
Completed and registered in Tokyo. Her gross registered tonnage and net registered tonnage are 1.911-tons and 1,057-tons respectively. Her call sign is JPYN. [1]
3 December 1940:
Requisitioned by the IJN.
16 December 1940:
Uraga Dock K.K. shipyard. Begins conversion to military duty.
25 December 1940:
Registered in the IJN as an auxiliary gunboat and attached to the Yokosuka Naval District with Yokosuka as homeport under internal order No. 1020. Capt. Aoki Setsuji is appointed Commanding Officer.
6 January 1941:
Lt. Kawada Yoshio is appointed Commanding Officer.
14 January 1941:
Conversion is completed.
15 January 1941:
Attached to the Combined Fleet Fourth Fleet Fifth Base Force
8 February 1941:
Departs Yokosuka for the South Sea area.
E February-July 1941:
Operates in South Seas District (Japanese mandated islands).
2 August 1941:
Arrives at Futami harbor, Chichi-Jima, Ogasawara Gunto (Bonins).
12 August 1941:
Departs Futami for the South Sea area.
E August-October 1941:
Operates in South Seas District.
2 September 1941:
Remains attached to the Fifth Base Force under Fourth Fleet wireless instruction No. 228.
15 October 1941:
Attached to the Seventh Gunboat Division under instruction No. 1250. Tactically attached to the Combined Fleet Fourth Fleet Fifth Base Force Seventh Gunboat Division.
20 November 1941:
Rated as an operation Ga [G or Guam] invasion unit under South Sea Unit command No. 1.
21 November 1941:
Rated as the First Patrol Unit under operation G Invasion Unit command No. 1.
23 November 1941:
Departs Saipan, Marianas and arrives later that day at Rota, Marianas.
30 November 1941:
Transfers back to Saipan.
1 December 1941:
Assigned to Guam (G) Invasion Group.
4 December 1941:
Transfers to Rota.
9 December 1941:
Departs Rota.
10 December 1941:
At 0526 shells Cape Shirai on Guam. Fires 18 shots. Transports the 18th Artillery Battery from Cape Shirai to Guam. At 1200 departs on a Guam East Coast patrol.
11 December 1941:
At 1856 heads towards Saipan
12 December 1941:
Calls at Rota and arrives at Saipan later this day.
13 December 1941:
The GA Invasion Unit is dissolved under South Sea Unit command No. 18.
14 December 1941:
Detached from Guam Invasion Group and assigned to South Seas Forces under instruction No. 18.
15 December 1941:
Classified as gunboat No. 72.
25 December 1941:
Departs Saipan.
26 December 1941:
Arrives at Guam (renamed Omiya-Jima after its capture).
5 January 1942:
Assigned to provide support to Marianas based troops for the scheduled “R” Operation.
9 January 1942:
Departs Guam.
10 January 1942:
Arrives at Saipan.
11 January 1942:
Departs Saipan.
11-13 January 1942:
Patrols waters before the “R” Operation Invasion Group.
13 January 1942:
Arrives at Saipan.
31 January 1942:
Departs Saipan.
1 February 1942:
Arrives at Guam.
17 February 1942:
Departs Guam.
18 February 1942:
Arrives at Saipan.
21 February 1942:
Departs Saipan.
21-24 February 1942:
On patrol mission.
24 February 1942:
Arrives back at Saipan.
26 February 1942:
Departs Saipan. Performs gunnery practice and returns to Saipan later in the day.
10 March 1942:
Departs Saipan for another gunnery drill and returns back to Saipan that same day.
13 March 1942:
Departs Saipan.
13-17 March 1942:
On a patrol mission.
17 March 1942:
Arrives at Saipan.
20 March 1942:
Departs Saipan.
20-21 March 1942:
On gunnery practice exercise.
27 March 1942:
Arrives at Saipan.
10 April 1942:
The 7th Gunboat Division is dissolved under Instruction No. 652. Attached that same day to the 4th Fleet, 5th Special Base Force.
30 April 1942:
Departs Saipan.
1 May 1942:
Arrives at Guam.
5 May 1942:
Departs Guam.
6 May 1942:
Arrives at Saipan.
14 May 1942:
Departs Saipan.
15 May 1942:
Arrives at Saipan. Departs later that day for Japan.
22 May 1942:
Arrives at Yokosuka.
16 June 1942:
Departs Yokosuka.
18 June 1942:
Arrives at Futami harbor, Chichi-Jima.
19 June 1942:
Departs Futami.
22 June 1942:
At 0500 at 33-20N, 140-00E discovers and engages enemy submarines.
23 June 1942:
Arrives at Yokosuka.
10 July 1942:
Removed from the Navy list under instruction No. 1218. Registered again that same day in the IJN as an auxiliary transport, (Ko) category and attached to the Yokosuka Naval District with Yokosuka as homeport under internal order No. 1219.Commanding Officer Lt. Kawada Yoshio is reassigned to the Yokosuka Naval District. [2]
12 July 1942:
Starts conversion to her new military role at the Yokosuka Naval Yard.
19 July 1942:
Navy (Resv) Hatai Masao is appointed Commanding Officer.
13 August 1942:
Conversion is completed.
14 August 1942:
Departs Yokosuka.
16 August 1942:
Arrives at Ominato, Aomori Prefecture.
20 August 1942:
Departs Ominato.
25 August 1942:
Attached to the Southwest Area Fleet.
13 September 1942:
Arrives at Kawasaki, Kanagawa Prefecture. Departs later.
18 September 1942:
Departs Yokosuka.
20 September 1942:
Arrives at Kure.
25 September 1942:
Departs Kure and arrives at Mutsure later in the day.
26 September 1942:
Departs Mutsure for Mako, Pescadores in convoy No. 167 also consisting of IJA transport HOUN MARU and two unidentified merchant ships escorted by destroyer WAKATAKE.
1 October 1942:
Arrives at Mako. Transfers later that same day to Takao, Formosa (now Kaohsiung, Taiwan).
3 October 1942:
Departs Takao.
22 November 1942:
Departs Surabaya, Java, Netherlands East Indies (now Indonesia) with auxiliary transport TARUSHIMA MARU and auxiliary gunboat MANYO MARU.
23 November 1942:
Auxiliary minesweeper Wa-3 departs Ambon, Maluku Islands, Netherlands East Indies (now Indonesia).
E 24 November 1942:
At unknown location auxiliary minesweeper Wa-3 meets up with auxiliary transports HIROTAMA and TARUSHIMA MARUs and auxiliary gunboat MANYO MARU and starts escorting them.
25 November 1942:
Auxiliary minesweeper Wa-3 arrives at Ambon.
26 November 1942:
Arrives with auxiliary gunboat MANYO MARU and auxiliary transport TARUSHIMA MARU at Ambon.
5 February 1943:
At unknown location auxiliary minesweeper Wa-4 meets up with HIROTAMA MARU and starts escorting her.
8 February 1943:
Arrives at Kendari, Celebes, Netherlands East Indies. (now Sulawesi, Indonesia. Escort of auxiliary minesweeper Wa-4 ends.
14 February 1943:
Makassar Strait. About 73 nautical miles W of Cape Mandal, Celebes (now Mundala, Sulawesi), LtCdr (later Vice Admiral/MOH) Lawson P. Ramage's (USNA ’31) USS TROUT (SS-202) sights what he takes to be a tanker as it emerges from a rain squall. About 0800, Ramage makes a submerged attack and fires two torpedoes. The first torpedo hits and blows off HIROTAMA MARU’s bow, but the second is a dud. As the transport resumes course at eight knots, USS TROUT battle surfaces and opens fire with her deck guns, but soon seven of her men are wounded by the transport’s machine guns. Ramage then swings around and fires a stern torpedo that mortally hits HIROTAMA MARU. She slips under, stern straight up and screws still turning at 03-59S 117-30E taking down 29 crewmen.
1 April 1943:
Removed from the Navy’s list under internal order No. 587.

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

Thanks go to Berend van der Wal of Netherlands and Gengoro S. Toda of Japan.

Gilbert Casse, Bob Hackett and Peter Cundall

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