Auxiliary Submarine Tenders

TOKUSETSU SENSUI-BOKAN!

(Nachi Maru as a prewar OSK liner)

IJN Submarine Tender
NACHI MARU: Tabular Record of Movement
© 1998-2020 Bob Hackett, Berend van der Wal, Sander Kingsepp and Peter Cundall
Revision 3

3 May 1926:
Kobe. Laid down at Mitsubishi Heavy Industries’ shipyard as a 1,605-ton passenger/cargo ship for the Osaka Shosen K.K. (OSK) Line.
9 October 1926:
Launched and named NACHI MARU.
20 December 1926:
Completed. Her Gross Registered tonnage (GRT) and Net Registered Tonnage (NRT) respectively are 1,600-tons and 751 tons. [1]
1 February 1927:
Departs Kobe for Katsuura.
3 February 1927:
Returns to Kobe and departs again for Katsuura on regular run.
12 December 1933:
Departs Kobe for Beppu on new run. Later, reverts to Kobe-Katsuura route.
10 July 1935:
Reverts again to Kobe to Beppu run. Later, again reverts to Kobe-Katsuura run.
1936:
Her GRT is changed to 1,602-tons. [1]
1937:
Her GRT is changed to 1,606-tons. [1 ]
1938:
NACHI MARU's name is re-rendered as NATI MARU. [2]
August 1938:
Reverts again to Kobe-Beppu run.
September 1938:
Transfers to Kochi-Sakaide-Tadotsu service.
February 1939:
Transfers to Imaari-Kochi service. Later that year, transfers to Kobe-Imabari service route.
1941:
Her GRT and NRT are respectively changed to 1,605-tons and 749-tons respectively. [1]
4 May 1942:
Sold to Kansai Kisen, K.K., Osaka. Operates on Osaka-Komatsushima Line's express passenger/cargo service.
8 May 1942:
Departs Manila.
21 January 1943:
Requisitioned by the IJN.
15 February 1943:
Registerd as an auxiliary gunboat under instruction No. 259. Attached to the Osaka Security Force Unit. Navy (Resv) Lt Kinbara Masaji is appointed CO. Completes docking outfitting at Harima Zosen’s yard.
20 February 1943:
13 March 1943:
Rated as Sea Defense Force E unit (16) under Osaka Guard Office instruction No. 23.
21 March 1943:
Aioi. Completes conversion to an auxiliary gunboat at Harima Zosen's yard. Departs Osaka and arrives at Yuranai (Outer Yura), SW Honshu, on the Inland Sea later that day.
23 March 1943:
Departs Yura on regular patrols of the Kii Suido area. [3]
26 March 1943:
Arrives at Yura.
28 March 1943:
Departs Yura.
30 March 1943:
Arrives at Yura.
1 April 1943:
Departs Yura.
4 April 1943:
Arrives at Yura.
6 April 1943:
Departs Yura.
10 April 1943:
Arrives at Yura.
13 April 1943:
Departs Yura.
14 April 1943:
Arrives at Yura.
20 April 1943:
Departs Yura.
24 April 1943:
Arrives at Yura.
28 April 1943:
Departs Yura.
1 May 1943:
Arrives at Yura.
7 May 1943:
Departs Yura.
10 May 1943:
Arrives at Yura.
12 May 1943:
Departs Yura.
13 May 1943:
Arrives at Yura.
15 May 1943:
Departs Yura.
18 May 1943:
Arrives at Yura.
23 May 1943:
Departs Yura.
28 May 1943:
Arrives at Yura.
2 June 1943:
Departs Yura.
8 June 1943:
Arrives at Yura.
10 June 1943:
Departs Yura.
13 June 1943:
Arrives at Yura.
19 June 1943:
Departs Yura.
22 June 1943:
Arrives at Yura.
30 June 1943:
Departs Yura.
8 July 1943:
Arrives at Yura.
11 July 1943:
Departs Yura.
14 July 1943:
Arrives at Yura.
18 July 1943:
Departs Yura.
24 July 1943:
Arrives at Yura.
26 July 1943:
Departs Yura.
27 July 1943:
Direct escort for convoy No. 8727 from offshore Yura to near Mikizaki under Marine Defense wireless instruction No. 13. After the escort mission go to Tanabe on standby under Marine Defense Command instruction No. 14.
28 July 1943:
Standby assignment at Tanabe is cancelled and has to return to Yuranai under Marine Defense Command instruction No. 15. Arrives at Yuranai later this day.
31 July 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
3 August 1943:
Arrives at Yuranai.
5 August 1943:
Departs Yuranai.
7 August 1943:
Arrives at Yuranai.
9 August 1943:
Departs Yuranai.
10 August 1943:
Arrives at Osaka, probably enters dock.
4 September 1943:
Departs Osaka and later that day arrives at Yuranai.
7 September 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
10 September 1943 :
Arrives at Yuranai.
12 September 1943:
Departs Yuranai and arrives at Kobe later that day.
13 September 1943:
Departs Kobe for an anti submarine training and arrives at Yuranai later this day.
14 September 1943:
Departs Yuranai for an anti submarine training and arrives at Yuranai later that day.
15 September 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
18 September 1943:
Arrives at Yuranai.
19 September 1943:
Ordered to depart as soon as ready in cooperation with auxiliary minesweeper No. 32 (Wa-32) under Maritime Defense Telegraph Service instruction No. 6. Departs Yuranai on an anti submarine sweep.
20 September 1943:
Departs Yuranai.
21 September 1943:
Departs Wakaura on an anti submarine sweep.
24 September 1943:
Arrives at Yuranai.
26 September 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
28 September 1943:
Continues on site mission under Marine Defense wireless instruction No. 7.
29 September 1943:
Arrives at Yuranai.
1 October 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
4 October 1943:
Arrives at Yuranai.
8 October 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
11 October 1943:
Arrives at Yuranai.
16 October 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
20 October 1943:
Arrives at Yuranai.
22 October 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
24 October 1943:
Arrives at Yuranai.
29 October 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
1 November 1943:
Arrives at Yuranai.
2 November 1943:
Departs Yuranai and returns later this day.
6 November 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
9 November 1943:
Arrives at Yuranai.
11 November 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
13 November 1943:
Arrives at Yuranai.
16 November 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
19 November 1943:
Arrives at Yuranai.
20 November 1943:
Departs Yuranai on Hanko Ikai land battle excercise.
21 November 1943:
Arrives at Yuranai.
22 November 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
25 November 1943:
Arrives at Yuranai.
29 November 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
2 December 1943:
Arrives at Yuranai.
6 December 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
9 December 1943:
Arrives at Yuranai.
12 December 1943:
Departs Yuranai on a patrol. Later calls at Oshima.
13 December 1943:
At 0300, recovers the pilot from a German ship. At 0700, completes escort to Murotozaki.
14 December 1943:
Arrives at Yuranai.
16 December 1943:
Departs Yuranai on a patrol. Later calls at Oshima, thereafter continues her patrol.
19 December 1943:
Arrives at Yuranai. Departs on an anti submarine training later that day.
20 December 1943:
Departs Yuranai.
21 December 1943:
Arrives at Yuranai.
22 December 1943:
Departs Yuranai on an anti submarine training and returns later this day.
23 December 1943:
Receives wireless message No. 8.: Rush to the distress site of the German passenger/cargo ship HAVELLAND and while under command of the 32nd Minesweeping Command engage in anti submarine sweeping and towing of the HAVELLAND. Accordingly, departs Yuranai.
Instructed to tow the HAVELLAND to Oshima harbor under the 32nd Minesweeper wireless instruction No. 1.
Instructed to carry out an anti submarine sweep west of the I line under Coast Guard message No. 230717.
After ending towing of the HAVELLAND through the Shiono Misaki Passage instructed to escort convoy No. 7222 at 1720 from Off Shingu to Seto Zaki under Sea Defense message No. 231142.
At 1230, arrives at the disaster site. At 1330, starts towing the HAVELLAND to the east of Toshima Zaki on Oshima and is scheduled to anchor near Hakojima at 2000.
Instructed to tow HAVELLAND to Kushimoto under message No. 231455.
Expects to arrive at 1505 because freedom of towing steering is not effective.
Instructed to tow HAVELLAND to Oshima harbor under Osaka Guard message No. 231716. At 1830, has the HAVELLAND anchored at 298 degrees and 2 nautical miles of Kashino Zaki.
24 December 1943:
Receives message No. 241230. Minesweeper no. 32: acting offshore Seto Zaki, exept for convoy escorts, sweeping merchant shipping routes.
At 1430, starts patrol off the coast of Seto Zaki.
Instructed to escort convoys No. 8223 and 8224 from Seto Zaki to Shingu under wirelles No. 53.
At 2200, at Kirime Zaki jons the convoy.
25 December 1943:
At 0235, at 180 degrees and 5 nautical miles of Cape Tide the convoy is attacked with torpedoes by a submarine. At 0240, torpedoed during a depth charge attack but sustains no damage. At 0335, at 165 degrees and 7 nautical miles of Cape Tide drops 12 depth charges.
Instructed to resupply depth charges at Tanabe after completing the escort under Maritime Defense message No. 250453.
At 0740, at 135 degrees and 6,8 nautical miles of the Tide Point lighthouse sets out a buoy with a red flag. Thereafter heads to Tanabe where she arrives later this day. At 1800, loading of 24 depth charges is completed.
Receives message No. 55: Instructed to escort the HAVELLAND to the vicinity of Seto Zaki on 26 December 1943. After this mission is completed head to Yura for resupply and a sweeping mission.
Departs Tanabe later that day. At 2000, strong wind makes patrolling difficult.
26 December 1943:
At 1045, departure from the harbor is cancelled because of strong wind. Instructed to carry out instruction No. 56 on 27 December 1943 under Marine Defense instruction No. 56.
27 December 1943:
At 0700, escorts HAVELLAND. At 1225, at 210 degrees and 2 km of Shiono Mizaki auxiliary transport KIMIKAWA MARU is torpedoed. At 1255, drops 12 depthcharges in the vicinity of the target. At 1410, instructed to return at 1500 to the HAVELLAND and resume escort if situation remains unchanged.
Receives Coast Defense instruction No. 59: End search for enemy submarines apporiately and escort the Havelland.
At 1455, drops 6 depthcharges. At 1505, collaborates the attack with a seaplane and drops 4 depthcharges. At 1530, heads to Shi Ezaki lighthouse to escort the HAVELLAND. At 1815, instructed to return to homeport when the HAVELLAND passes Seto Zaki at 2100. Arrives at Yuranai later this day.
28 December 1943:
Departs Yuranai.
Instructed to escort auxiliary cablelayer HARUSHIMA MARU from Kandori Zaki to Seto Zaki under Sea Defense message No. 82105.
29 December 1943:
At 0545, reports she can’t meet up with auxiliary cablelayer HARUSHIMA MARU.
Instructed to escort convoy No. 7228 from Kandori Zaki to Seto Zaki under Coast Defense instruction No. 960.
At 1430, begins escorting convoy No. 7228 off Nandori Zaki. At 2015, escort of convoy No. 7228 ends. Begins a patrol off Seto Zaki.
Instructed to escort AWASARU MARU from Shiono Mizaki to Seto Zaki under Marine Defense instruction No. 177.
Instructed to escort convoy No. 7229 from Cape Shiono Mizaki to Seto Zaki under Sea Defense instruction No. 269.
30 December 1943:
Arrives at Yuranai.
31 December 1943:
Instructed to carry out an anti submarine sweep at 191 degrees and 2800m off Shiono Mizaki under Coast Defense instruction No. 62.
Instructed to carry out an anti submarine sweep on the convoy route and escort convoys within 10 nautical miles of Cape Shiono Mizaki and line I under 32nd. Minesweeper Command message No. 311135.
Departs Yuranai on an anti submarne sweep later that day.
1 January 1944:
Arrives at Yuranai.
4 January 1944:
Departs Yuranai.
5 January 1944:
Arrives at Yuranai.
8 January 1944:
Arrives at Osaka and enters drydock.
16 February 1944:
Departs Osaka.
17 February 1944:
Arrives at Yuranai. Assigned to an emergency transport to the South Sea under message No. 171935.
20 February 1944:
Departs Yuranai.
22 February 1944:
Transport Message No. 222049: Products for Yokosuka properly loaded and departs to Yokosuka.
26 February 1944:
Arrives at Yokosuka.
1 March 1944:
Departs Yokohama escorting convoy Higashi-Matsu 1B.
6 March 1944:
Arrives at Chichi-Jima with convoy Higashi-Matsu No. 1B.
7 March 1944:
At 1300, NACHI MARU departs Chichi-Jima for Truk with minelayer YURIJIMA and auxiliary minesweeper TORISHIMA MARU escorting convoy Higashi-Matsu 1B consisting of IMIZU, HOKO and SHINFUKU MARUs.
14 March 1944:
Arrives at Truk. Departs Truk for Saipan escorting convoy Higashi-Matsu No. 2.
24 March 1944:
At 0700, departs Saipan in convoy HIGASHI MATSU No. 2 (return) consisting of NACHI, TAKUNAN, AWA (ex-WAWA), DAITEN, MIHO, BINGO, RYUKA (YANAGAWA), TAKAOKA, HIBI, TAMAHOKO, TATSUHARU and SHINFUKU MARUs, fleet supply ship SOYA and an unidentified vessel escorted by destroyers NOWAKI, ASAKAZE, kaibokan MANJU and minelayer KYOSAI and subchasers CH-17, CH-31 and CH-32. At 1730 minelayer KYOSAI discovers something that seems to be a periscope and carries out surveillance pressure for 3 hours.
25 March 1944:
At 0500, minelayer KYOSAI rejoins with the convoy.
26 March 1944:
At 1300, at 20-58N,142-45E one of fleet supply ship SOYA’s boiler fails and is unable to continue. Minelayer KYOSAI escorts SOYA to Chichi-Jima.
28 March 1944:
Arrives at Chichi-Jima with convoy Higashi-Matsu No. 2.
1 April 1944:
Arrives at Tokyo.
2 April 1944:
Receives wireless No. 264: 1 Scheduled with minelayer KYOSAI to escort convoy No. 4324 consisting of supply ship SOYA, auxiliary transports SHIBAZONO and NISSHO MARUs and ASAHI MARU No. 2 from Chichi-Jima on 3 April 1944.
2 The commander of escort force commands subordinate ships as appropiate and on the morning of 3 April 1944 departs Yokosuka, searches south along the archipelago route.
Approximately 30 degrees and 50 minutes noth latitude near the 30th. and 50th. line meets with the previous section of the convoy and receives the command of the Commanding Officer of the SOYA.
4 April 1944:
Departs Chichi Jima escorting convoy No. 4324 consisting of AWA and NISSHO MARUs, fleet supply ship SOYA and auxiliary minesweepers KEINAN MARU and TOSHI MARU No. 8, auxiliary netlayer KOGI MARU and auxiliary submarine chaser FUMI MARU.
5 April 1944:
Departs Chich-Jima to escort convoy No. 4324.
6 April 1944:
At 31N KEINAN MARU is detached and returns to Chichi Jima. The convoy continues on to Yokosuka.
15 April 1944:
Departs Yokosuka.
16 April 1944:
Arrives at Yuranai.
20 April 1944:
Departs Yuranai and later that day arrives at Kushimoto.
23 April 1944:
Departs Kushimoto. Scheduled for antisumbarine sweeping between 0730 and 0845 at Shiono Mizaki.
Assigned to escort convoy No. 8423B from off Iechiezaki and off Shingu under Sea Defense instruction No. 231811.
At 2000, at 180 degrees and 10 nautical miles of Shiono Mizaki carries out an anti submarine sweep. At 2253, at 180 degrees and 15 nautical miles of Shiono Mizaki torpedoed but apparently sustains no damage
24 April 1944:
At 0000, drops 22 depthcharges after wich 8 remain. At 0930 has dropped a total of 28 depthcharges since yesterday. 8 depthcharges remain.
Instructed to resupply depthcharges at Kushimoto under Defense instruction No. 241122.
At 1500, ends escorting convoy No. 8423B and arrives at Kushimoto later this day. At 2100, completes resupply with depthcharges. Departs Kushimoto later that evening.
25 April 1944:
At 0700, at 90 degrees and 12 nautical miles of Kandori Zaki course is 235 degrees and speed is 7 knots. At 1100, at 190 degrees and 8 nautical miles of Shiomisaki the course is 50 degrees and the actual speed is 7 knots. Assigned to standby in Yura. Arrives at Yuranai later that day.
26 April 1944:
Departs Yuranai. Performs first sweep deployment under Marine Defense wireless instruction No. 8.
Assigned to attack enemy submarines at 215 degrees and 4 nautical miles of Ichiezaki under Sea Defense instruction No. 260910.
While performing anti submarine sweeping assigned to stop and instantly escort convoy No. 7424 consisting of SHISEN, KANZAKI, YOZAN and SEIWA MARUs from Off Shingu to Off Setozaki under instruction No. 261358.
At 1445 assigned to sweep after 1800 east from the 200 degree line within 20 nautical miles of Ichiezaki.
Assigned to patrol the homeport patrol area after completing the escort of convoy No. 7424 under Marine Defense instruction No. 4.
Assigned to escort convoy No 8424, No. 8425 and No. 8426 from Setozaki to Shingu-kan under Coast Defense insruction No. 261645.
At 1730 reports that she couldn’t meet up with convoy no. 7424 off Kandorizaki.
Receives message Sea Defense No. 261755 stating that convoy No. 7424 temporary stays at Owase under Marine Defense Ordinance no. 4 and Maritime instruction No. 261645.
At 1940 turns back for deployment at her homeport.
27 April 1944:
After escorting the eastbound convoy assigned to escort convoy No. 7424 from Setozaki to Shingu under Sea Defense instruction No. 271025.
At 1140 all depthcharges have been dropped and is ready for resupplying at Kushimoto. Arrives at Kushimoto later this day.
At 1500 resupplied with 48 depthcharges. Therafter departs Kushimoto.
At 1620 drops 1 depthcharge at 135 degrees and 4 nautical miles of Shionomisaki.
After completing the escort after 1800 the First Sweeping Squadron will deploy at Shionomisaki under Marine Defense instruction No. 6.
Assigned to escort convoy No. 8426B from Kushimoto oki and Shingu oki. Thereafter asigned to escort convoy No. 8427 to Off Shingu and then to escort convoy No. 7423 to Off setozaki under Coast Guard instruction No. 271830.
28 April 1944:
At 0340, at 196 degrees and 2 nautical miles off Shionomisaki torpedoed from the port side. At 60 degrees attacked with more torpedoes but sustains no damage. Performs an anti submarine attack. At 0445 after dropping 21 depthcharges departs to escort convoy No. 8426B. At 0630 returns to Kushimoto. At 0820, returns to Off Shionomisaki for anti submarine sweeping. At 0840, Scheduled to arrive at 205 degrees and 8 nautical miles of Shionomisaki.
Assigned to escort convoy 8426B from Shionomisaki to Shingu oki and then to escort convoy No. 7426 from Shingu oki to Z oki under Sea Defense instruction No. 281825.
30 April 1944:
Assigned to escort convoy 8429B from Shionomisaki to Kandorizaki and then to escort convoy No. 7428 from Kandorizaki to Ichiezaki under Sea Defense instruction No. 301725.
At 1530, reports it can’t meet up with convoy No. 7428 off Shingu.
Assigned to perform the third anti submarine sweep according to the first escort procedure and to stand by Kushimoto under Sea Defense instruction No. 7.
1 May 1944:
Navy (Resv) Cdr. Kanahera Seiji is appointed Commanding Officer.
Assigned to escort NORFOLK MARU from Kandorizaki to Ichiezaki under Coast Defense instruction No. 011815
2 May 1944:
Arrives at Kushimoto.
3 May 1944:
Assigned to escort convoy No. 8503 on 4 May 1944 from Setozaki to Kandorizaki under Coast Defense instruction No. 031600.
4 May 1944:
Departs Kushimoto escorting convoy No. 8503. Returns later that day.
Assigned to escort convoy No. 7502 on 5 May 1944 from Setozaki to Kandorizaki under Coast Defense instruction No. 041620.
5 May 1944:
Departs Kushimoto escorting convoy No. 7502. At 1050, while escorting convoy No. 7502 heads towards distress site at 33-27N, 135-33E.
Assigned to escort convoy No. 8505 on 6 May 1944 from Ichiezaki to Kandorizaki under Coast Defense instruction No. 051600.
At 1700, completes escorting convoy No. 7502. Off Shionomizaki drops 2 depthcharges for deterrence.
The captain of the auxiliary subchaser HAYATOMO MARU is designated as the Commander of the SHIRANE MARU rescue team under instruction No. 050142.
Assigned to carry out an anti submarine sweep within 10 to 20 nautical miles of the coast under Marine Defense instruction No. 051735.
6 May 1944:
Assigned to escort convoy No. 8506 on 7 May 1944 from Ichiezaki to Kandorizaki under Defense instruction No. 061545.
At 1330, assigned to instantly carry out an anti submarine sweep and assist and rescue the crew of the torpedoed German ship Rossbach (ex Norwegian oil tanker MADRONO). From 1700 till 1800 at 180 degrees and 21 nautical miles of Ichiezaki on course 270 degrees and with a speed of 10 knots searches and sweeps for enemy submarines while heading towards the distress site.
Assigned to escort convoy No. 7506 on 8 May 1944 from Kandorizaki to Ichiezaki under Coast Defense instruction No. 071701.
8 May 1944:
Instructed to wait at Kushimoto after completing the convoy escort under Instruction No. 081106.
At 1120, completes the convoy escort.
Assigned to escort convoy No. 7506 on 9 May 1944 in PZ area under Coast Defense instruction No. 081807.
9 May 1944:
Assigned to escort convoy No. 7508 and No. 8509 on 10 May 1944 from Ichiezaki to Kandorizaki under Coast Defense instruction No. 091545.
10 May 1944:
Execute the first escort procedure as alternative during the third sweeping deployment at Kushimoto base and during escorting under Sea Defense instruction No. 101138.
11 May 1944:
Assigned to escort convoy No. 7508 and No. 7509 (in case of simultaneous departure) on 12 May 1944 between Ichiezaki and Shionomisaki. After completing escort wait at Kushimoto under Coast Defense instruction No. 111826.
Arrives at Kushimoto later this day.
12 May 1944:
Assigned to escort the HIGASHI MARU from Shingu oki (Shin Miyaoki) to Ichiezaki on 13 May 1944 under Coast Defense instruction No. 121732.
13 May 1944:
Departs Kushimoto on escorting a convoy and returns later that day.
14 May 1944:
Assigned to escort convoy No. 8514 from Ichiezaki to Kandorizaki on 15 May 1944 under Sea Defense instruction No. 141652.
15 May 1944:
Departs Kushimoto on escorting a convoy and returns later that day.
Assigned to escort convoy No. 7575 and SHUYO MARU from Kandorizaki to Ichiezaki on 16 May 1944 under Sea Defense instruction No. 151903.
16 May 1944:
Departs Kushimoto. Assigned to escort SEIKO MARU No. 2 from Kandorizaki to Ichiezaki on 16 May 1944 under Sea Defense instruction No. 160845.
Assigned to escort convoy No. 8516 from Ichiezaki to Shingu under Defense instruction No. 161634 on 17 May 1944.
Assigned escort as main task with standby place as before under Naval Defense wireless No. 3: Third Patrol Forces Department. 17 May 1944:
Assigned to escort convoy No. 7516 from Shingu to Ichiezaki on 18 May 1944 under Defense instruction No. 171644.
18 May 1944:
Assigned to escort TAIRAI MARU from Ichezaki to Shionomisaki on 19 May. After completing escort go to Yura under Sea Defense instruction No. 181632.
19 May 1944:
Arrives at Yuranai.
20 May 1944:
Assigned to escort a convoy on the west sea above Shionomisaki in cooperation with the Third Maritime Guard under Osaka Security Guard Ordinance No. 46.
21 May 1944:
Assigned to escort SAGAMIGAWA MARU from Shionomisaki to Setozaki on 22 May. After completing the escort to go to Yura under Sea Defense instruction No. 211805.
22 May 1944:
Departs Yuranai escorting a convoy.
23 May 1944:
Arrives at Yuranai. Assigned to escort convoy No. 8523 from Setozaki to Shionomisaki on 24 May 1944. After completing the escort to wait at Kushimoto under Sea Defense instruction No. 231542.
24 May 1944:
Departs Yuranai escorting a convoy and arrives at Kushimoto later this day.
25 May 1944:
Assigned to escort convoy No. 7524 from Somnomisaki to Setozaki on 26 May 1944. After completing the escort wait at Yura under Sea Defense instruction No. 251406.
26 May 1944:
Departs Kushimoto escorting a convoy and arrives at Yuranai later that day.
30 May 1944:
Departs Yuranai. At 1450, completes anti submarine training. At 1730, completes landing at Wakaura. At 1930, scheduled to return to Yuranai. Arrives at yura later this day.
31 May 1944:
Assigned to depart Yura at 0400 on 1 June 1944 for deployment as escort in the Susami Setozaki area for convoy No. 8531, convoy No. 7529, convoy No. 7530 first section, convoy No 7530 second section and SEIKO MARU section under Sea Defense instruction No. 311638.
1 June 1944:
Departs Yuranai. At 1330 while escorting convoy No. 7530 carries out an anti submarine sweep. Drops depthcharges at 145 degrees and 3.5 nautical miles of Ichiezaki. At 1500, a large amount of light oil gushes from the depth charge point. It aligns with the WAZAN MARU sinking point. One drum can made in Japan is collected.
Assigned to escort convoy No. 8601 westbound MARU section from Setozaki to Susami on 2 June 1944 under Sea Defense instruction No. 011545.
At 1730, today’s escort mission of escorting SEIKO MARU passed safely. Ends the escort.
2 June 1944:
Assigned to escort from Susami to Setozaki convoy No. 7601, convoy no. 7602 second section, east bound TAIAN MARU and west bound SHINBU MARU on 3 June 1944 under Sea Defense instruction No. 021652.
Assigned to stay at Tanabe after completing today’s escort assignmenets under Coast Defense instruction No. 022042.
3 June 1944:
Assigned to escort from Setozaki to Shionomisaki TATSUE MARU and convoy No. 7602 on 4 june 1944. After completing escort head to Yuranai under Defense instruction No. 031636.
Arrives at Yuranai later this day.
4 June 1944:
Arrives at Yuranai.
9 June 1944:
Departs Yuranai.
11 June 1944:
Assigned to escort HAWAII MARU to patrol area under Sea Defense instruction No. 111523.
Assigned to escort convoy No. 8611 and convoy No. 7610 from Setozaki to Susami on 12 June under Defense instruction No. 111535.
12 June 1944:
Arrives at Yuranai.
15 June 1944:
Departs Yuranai. Assigned to escort convoy No. 8615, convoy No. 7614, salvage tug NASU MARU, 4 high speed armored motor boats and eastbound SHIMA MARU on 16 June 1944 under Sea Defense instruction No. 151703.
16 June 1944:
Arrives at Yuranai. Departs Yuranai later this day and arrives at Osaka later that day.
19 June 1944:
Departs Osaka and later that day arrives at Yuranai.
21 June 1944:
Assigned to depart at 0800 on 22 June 1944 for deployement to A patrol area under Coast Defense instruction No. 211545.
22 June 1944:
Departs Yuranai.
23 June 1944:
Scheduled to be replaced by auxiliary subchaser HAYATOMO MARU on 24 June 1944 under Defense instruction No. 231530.
24 June 1944:
Arrives at Yuranai.
25 June 1944:
Assigned to depart at 0800 on 26 June 1944 for deployement to A patrol area under Coast Defense instruction No. 251535.
26 June 1944:
Departs Yuranai.
28 June 1944:
Escorts light cruiser OYODO and 2 destroyers between Shionomisaki and Setozaki.
29 June 1944:
At 1225, at 280 degrees and 14000 meters from Setozaki executes an anti submarine sweep. From 1400 till 1430 executes anti submarine sweep. At 1530, arrives Off Setozaki. At 1730, at 250 degrees and 7 nautical miles of Shionomisaki detects several echoes. Drops 4 depth charges.
Assigned to wait at Tanabe if situation doesn’t change under Coast Defense instruction No. 291950.
At 2045, used 10 depth charges. Confirms no abnormalities. Waits in Tanabe Bay. Arrives at Tanabe later this day.
30 June 1944:
Assigned to wait for a return voyage to Tanabe if situation doesn’t change up to 1200 under Sea Defense instruction No. 3021045.
1 July 1944:
Scheduled to be replaced by auxiliary subchaser KOCHI MARU and to depart Tanabe for deployment in area A on 2 July at 0800 under Defense instruction No. 011500
2 July 1944:
Departs Tanabe. Scheduled to be replaced by auxiliary subchaser KIYO MARU on 3 July 1944 at 1200 and deployment in area O intil 5 July 1944 under Defense instruction No. 021630.
4 July 1944:
Assigned to stop current mision and to return swiftly to Yuranai under Defense instruction No. 041025. Arrives at Yuranai later this day.
7 July 1944:
Assigned to depart at 0800 on 8 July 1944. After convoy escort, wait at Tanabe under Defense instruction No. 071645.
8 July 1944:
Departs Yuranai.
10 July 1944:
Arrives at Tanabe.
12 July 1944:
Assigned to depart at a convenient time for deployment during the day under Sea Defense instruction No. 121615.
13 July 1944:
Departs Tanabe. Assigned to escort convoy No. 7711 and thereafter return to Yuranai under Defense instruction No. 131600. Arrives at Yuranai later this day
14 July 1944:
Departs Yuranai.
15 July 1944:
Arrives at Osaka for drydocking.
22 August 1944:
Departs Osaka.
24 August 1944:
Arrives at Yuranai.
25 August 1944:
Assigned to depart at 0730 on 26 August 1944 for deployment in area A under Coast Defense instruction No. 251522
26 August 1944:
Departs Yuranai. Assigned to wait at Tanabe after escort on 27 August 1944 under Defense instruction No. 261533.
27 August 1944:
Departs Tanabe. Assigned to return to Yuranai after escort on 28 August 1944 under Sea Defense instruction No. 271607.
28 August 1944:
Arrives at Yuranai.
30 August 1944:
Assigned to depart at 0730 on 31 August for deployment in patrol area A and to be replaced by auxiliary minesweeper WA-22 under Sea defense instruction No. 301552.
31 August 1944:
Departs Yuranai. At 1430 at 315 degrees and 8.6 nautical miles off Ezaki kaibokan CD-34 detects an enemy submarine. Together with CD-34 executes a depth charge attack. At 1550 CD-34 reports: "I don’t find the enemy submarine. I doubt my previous detection."
The captain of the NACHI MARU detaches from the sweeping squadron under Sea Defense instruction No. 311645.
From 1940 till 2000 sweeps area Roja. Thereafter departs.
1 September 1944:
Assigned to wait at Tanabe after escorting if you get the enemy by 1600 under Defense instruction No. 011215.
Arrives at Tanabe later this day.
Assigned to depart at 0730 on 2 September 1944 for deployment in area A. After 1600 standby at Tanabe under Defense instruction No. 011609.
2 September 1944:
Departs Tanabe for deployment in area A and returns later that day.
Assigned to wait at Tanabe on 3 September 1944 after escort until receiving a special order under Sea Defense instruction No. 021509.
3 September 1944:
Departs Tanabe and returns later this day.
4 September 1944:
Assigned to depart Tanabe at 1000 on 5 September 1944 for deployment in area A under Defense instruction No. 041704.
5 September 1944:
Departs Tanabe. At 20 degrees and 9 nautical miles off Murotozaki enemy submarines are detected.
Assigned to move at high speed to the enemy submarine appearance site under Defense instruction No. 051642.
6 September 1944:
Assigned to escort HAKUTETSU MARU No. 7 and 10 Army Kihan ships on 7 September 1944 . After completing escort return to Yuranai at 1200 under Sea Defense instruction No. 061533.
Voyage to Yuranai on 7 September 1944 is cancelled. In stead deploy in area A with auxiliary subchaser HAYATOMO MARU under Sea Defense instruction No. 062208.
7 September 1944:
Assigned to wait at Tanabe after completing today’s escort under Defense instruction No. 071548.
Arrives at Tanabe.
8 September 1944:
Arrives at Yuranai.
10 September 1944:
Assigned to depart at a convenient time to escort convoy No. 8909 and convoy No. 8910. Therafter deploy in area A under Sea Defense instruction No. 101629.
11 September 1944:
Departs Yuranai.
Assigned to wait at Tanabe after completing today’s escort under Sea Defense instruction No. 111552.
Arrives at Tanabe later that day.
12 September 1944:
Departs Tanabe.
Assigned to return by sunset at 13 September 1944 under Sea Defense instruction No. 121618.
13 September 1944:
Arrives at Yuranai.
20 September 1944:
Navy LtCmdr Shimada Sueji is appointed CO.
22 September 1944:
Scheduled to depart at 0830 on 23 September 1944 under Sea Defense instruction No. 221619.
23 September 1944:
Departs Yuranai.
24 September 1944:
Arrives at Tanabe.
Assigned to escort convoy No. 8924 on 25 September 1944 and return after completing escort under Sea Defense instruction No. 241551.
25 September 1944:
Arrives at Yuranai.
E 26 September 1944:
Departs Yuranai.
27 September 1944:
Arrives at Yuranai.
30 September 1944:
Scheduled to depart at 0600 on 1 October 1944. After completing escort wait at Tanabe under Defense instruction No. 301621.
1 October 1944:
Departs Yuranai.
3 October 1944:
Assigned to carry out an anti submarine sweep at 270 degrees and 3.5 nautical miles off Setozaki under Defense instruction No. 032120.
Assigned to sweep area Lo Ha Ward under Sea Defense instruction No. 032230.
4 October 1944:
Assigned to sweep area Ha Ni Ho Ward at 0400 or later under Defense instruction No. 040130.
Assigned to continue anti submarine sweeping of the Ward tonight under Defense instruction No. 041528.
NACHI MARU sends message No. 041635: After 1800 sweep the Sento Ward north of the 230 line off Setozaki.
5 October 1944:
Arrives at Yuranai.
8 October 1944:
Departs Yuranai.
10 October 1944:
Assigned to return to Yuranai on 11 October 1944 while escorting KINYU MARU No. 2 under Sea Defense instruction No. 101614.
11 October 1944:
Arrives at Yuranai.
13 October 1944:
Scheduled for departure at 0800 on 14 October for deployment in area A under Sea Defense instruction No. 131608.
14 October 1944:
Departs Yuranai.
16 October 1944:
Assigned to escort today west of Esuzaki a passing convoy off Ichiezaki under Defense instruction No. 161035.
Assigned to return to homebase after being replaced by auxiliary minesweeper TAKASHIMA MARU No. 3 at Sho Ward on 17 October 1944 under Defens instruction No. 16108.
Arrives at Yuranai.
17 October 1944:
Arrives at Yuranai.
24 October 1944:
Assigned for deployment in area A on 25 October 1944 under Sea Defense instruction No. 241518.
25 October 1944:
Departs Yuranai.
26 October 1944:
Escorts cablelayer HATSUSHIMA. Assigned to be Night Guard on 27 October 1944 under Sea Defense instruction No. 261503.
29 October 1944:
Arrives at Yuranai.
1 November 1944:
Scheduled to depart at 0800 on 2 November 1944 under Defense instruction No. 011544.
2 November 1944:
Departs Yuranai.
7 November 1944:
Arrives at Yuranai.
10 November 1944:
Scheduled to depart at 0800 on 11 November 1944 under Defense instruction No. 101508.
11 November 1944:
Departs Yuranai.
12 November 1944:
Arrives at Tanabe. Assigned to escort an eastbound convoy on 13 November 1944 under Sea Defense instruction No. 121519.
13 November 1944:
Departs Tanabe and returns later this day.
15 November 1944:
Departs Tanabe.
16 November 1944:
Arrives at Kobe, probably for repairs.
7 December 1944:
Assigned to depart at 0800 on 8 December 1944 for deployment in patrol area A under Letter No. 071451.
8 December 1944:
Departs Kobe.
13 December 1944:
Assigned to return to homebase on 14 December 1944 under Coast Defense instruction No. 131509.
14 December 1944:
Arrives at Yuranai.
18 December 1944:
Assigned to depart at 0800 on 19 December 1944 for deployment in area A under Sea Defense instruction No. 181538.
19 December 1944:
Departs Yuranai for deployment in patrol area A.
20 December 1944:
Assigned night guard on 21 December 1944 under Defense instruction No. 201552.
24 December 1944:
Return to homebase after completing escort of convoy No. 8224 and guarding KAMOI on 25 December 1944 under Sea Defense instruction No. 241630.
25 December 1944:
Arrives at Yuranai.
28 December 1944:
Scheduled to depart at 0800 on 29 December 1944 for deployment in patrol area A under Sea Defense instruction No. 281555.
29 December 1944:
Departs Yuranai for deployment in patrol area A.
1 January 1945:
Assigned to return to homebase after completing escort on 2 January 1944 under Defense instruction No. 011612.
2 January 1945:
Arrives at Yuranai.
7 January 1945:
Assigned to depart at 1000 on 8 January 1945 for deployment in area A under Sea Defense instruction No. 071501.
8 January 1945:
Departs Yuranai for deployment in patrol area A.
14 January 1945:
Arrives at Yuranai.
January 1945:
Undergoes conversion to an auxiliary submarine depot ship.
20 January 1945:
Receives Osaka Guard Office instruction No. 4:
1 Make a round voyage to Otaka when ready.
2 Schedule daily action and report.
Completes conversion. Assigned to Vice Admiral, the Marquis, Daigo Tadashige's (40) (former CO of KINU) Kure SubRon as a depot ship for midget submarines.
21 January 1945:
Departs Osaka and later that day arrives at Yuranai.
24 January 1945:
Departs Yuranai and arrives at Otaka later this day.
25 January 1945:
At 1500 hoists the General flag.
30 January 1945:
Navy Lt Saito Horo is appointed Commanding Officer.
10 February 1945:
The Kure Submarine Squadron Commander and the Kure Navy Transport Director each dispatch a Kihan vessel requiered for the NACHI MARU and leave it at No. 61. Assigned to transport personnel and property from the Matsuyama Air Base Air Corps to the Iwakuni Air Base. The first on 14 February 1945. The second on 17 February 1945. Approximately 500 people and 200 properties will be on board. Finally the dispatched boat will depart as soon as it arrives at Matsuyama in the morning of the day before under Kure Guard Office instruction No. 61.
Assigned to sail at 0700 on 13 and 16 February 1945 from Otaka to Matsuyama each day, depending on Kure Guard Office instruction No. 61.
Engages in the 61st Air Base personnel and property transportation work and returns to Otake after the work is completed under Kure Submarine Squadron instruction No. 33.
12 February 1945:
The flag is to be relocated at 0700 to the submarine corps building on 13 and 16 February 1945 respectively and then on 14 and 17 February 1945 respectively to NACHI MARU in Otaka port under Kure Submarine Squadron instruction No. 34.
13 February 1945:
At 0730 the General flag is moved to the submarine government office. Therafter departs Otake and arrives at Mitsukehama later this day.
15 February 1945:
Arrives at Iwakuni.
16 February 1945:
Departs Iwakuni and later that day arrives back at Otaka. At 1330 the General flag returns.
27 February 1945:
At 1630 the General flag is moved to the submarine government office. Thereafter departs Otaka and arrives at Yanai later this day. At 1900 the General flag returns.
28 February 1945:
Departs Yanai and arrives at Otake later that day.
6 March 1945:
Assigned to return to Otake after participating in the underwater antenna comparison test from Otake on 8 March 1945 under Kure Suibmarine Squadron wireless instruction No. 14.
8 March 1945:
At 0930 the General flag is moved to the submarine government office. Thereafter departs Otake and arrives at Agenosho later this day.
10 March 1945:
Departs Agenosho and arrives at Otake later that day. At 2130 the General flag returns.
16 March 1945:
Navy diving training ship NACHI MARU is now to be equipped with water measuring weapons. One set of 3 types of type 3 detetective. A type 93 sounding device type 2 for small vessels and a type 3 underwater sound device under Ship instruction No. 788.
At 0700 the General flag is moved to the submarine government office Thereafter departs Otaka and arrives at Kure later this day.
20 March 1945:
Kure. Rear Admiral Owada Noboru’s (44)(former CO of YAMASHIRO) Tenth Special Attack Force is formed at Kure and attached directly to HQ, Combined Fleet. The unit, consisting of 13 Koryu midget submarines, is tasked with developing new tactics for future Koryu and Kairyu midget submarine attacks.
23 March 1945:
Departs Kure.
24 March 1945:
Arrives at Harima. Reconstruction work at Harima Shipyard as well as instructional work on water measurement weapons equipment begins based on Ship instruction No. 788. Remains there under repair throughout April.
2 April 1945:
Receives Warship Navigation instruction No. 153: a notification of supply of weapon: Four small sets of magnetic compass should be supplied during the period for student navigation training. The rest of the month the reconstruction work at Harima Shipyard as well as instructional work on water measurement weapons equipment continuous. The main gun is removed and she is equiped with 2 sets of 25 mm machine guns.
25 May 1945:
Departs Otaka.
28 May 1945:
Arrives at Maizuru.
30 May 1945:
Departs Maizuru. Later that day, arrives at Anamizu.
6 June 1945:
Departs Anamizu.
9 June 1945:
Arrives at Ananmizu.
20 June 1945:
Departs Anamizu.
28 June 1945:
Arrives at Anamizu.
12 July 1945:
Departs Anamizu.
14 July 1945:
Arrives at Kogushi.
16 July 1945:
Departs Kogushi. N of Kyushu, off Mutsure Jima, NACHI MARU is damaged severely by a mine, probably laid by USAAF’s 20th AF’s Boeing B-29 “Super Fortress” heavy bombers, at 33-59N, 130-52E. Later that day, arrives at Yoshimi. [4]
September 1945:
Surrendered to the Allied Powers. Later allocated SCAPJAP No. N-063.
1945:
Undergoes repairs at an undetermined location for an unknown period of time.
1946:
Assigned to the Allied Repatriation Service. [5]
3 May 1947:
Removed from the Navy List.
August 1947:
Returned to owners and placed in Kansai Kisen’s service on their Osaka-Beppu route.
October 1951:
In service on Kansai Kisen’s Osaka-Kochi route.
March 1954:
In service on Kansai Kisen’s Osaka-Okinawa route.
April 1960:
Sold to Yasushi Sano Dock service.
1961:
Scrapped.

Authors' Note:
[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] Kanji remains unchanged.
[3] NACHI MARU maintained regular patrols for rest of 1943 with gaps for convoy work throughout 1944.
[4] In 1945, the U. S. Army Air Force launched a five-phased campaign known as “Operation Starvation” to mine Japan’s home waters. The USAAF used 80 to 100 B-29 “Super Fortress” heavy bombers of the 21st Bomber Command based at Tinian in the Marianas. B-29s could carry seven 2,000 lb. or twelve 1,000 lb. mines.
Beginning on 27 March 1945 and continuing until 5 August 1945, B-29s flew 1,529 nighttime radar sorties and laid 4,900 magnetic, 3,500 acoustic, 2,900 pressure and 700 low-frequency mines for a total of more than 12,000 mines laid in Japanese waters. These mines sank 294 ships, damaged 137 beyond repair and damaged another 239 that could be repaired. The total was 1, 250,000 tons sunk or damaged or about 75 percent of Japanese shipping available in March 1945. Only 15 B-29s were lost during the mining campaign.
Postwar, removal of these mines posed a major challenge for the Allied Occupation Forces. They pressed 269 Japanese ships of various types into mine sweeping service to augment their own efforts.
[5] No data were been found indicating NACHI MARU made any repatriation voyages. She probably was still under repair in 1946.
Thanks go to Gilbert Casse of France for general assistance and the photo of NACHI MARU.
- Bob Hackett, Berend van der Wal, Sander Kingsepp and Peter Cundall.

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