Regulus-class Auxiliary Minelayers

These ships were designed as Gouvernementsmarine ships, but similar to the minelayer Rigel, also made suitable for carrying 80 mines, so that they could have an active part in naval warfare in the NEI, which relied for local defence mostly on minefields. According to other documents, they were also planned to act as seaplane tenders. They were in fact enlarged Rigel-class minelayers. By December 1941, these ships were still at the dockyard and were damaged by own forces in March 1942. They were both salvaged, but only one entered service with the Imperial Japanese Navy. The Japanese converted them to gunboats ( Tokusetsu Ho-Kan ), although Nankai retained her minelaying gear on the upper deck.

Nanshin line-drawing

Construction details
Name Nankai (ex-Regulus)
"South Sea"
Nanshin (ex-Ram)
"Advance South"
Dockyard Droogdok Mij Soerabaja Droogdok Mij Tandjong Priok
Laid down 1941 1941
Launched May 21 1943* December 10 1941
Commissioned June 7 1944 in IJN -
Status Damaged March 2 1942 by naval destruction parties, but only lightly damaged to stern. Repaired and commissioned, she was grounded on Sebuco Island on September 21 1944 after being hit by torpedo from Allied submarine**. Salvaged and repaired, but sunk by USS Blenny (SS-324) at 0500 hours 150 miles west of Soerabaja, July 16 1945. Removed from Navy list July 30 1945 Towed to Tjilatjap from December 14 to December 20. Destroyed by own forces March 1942. Towed to Soerabaja in May/June 1943 by Japanese and repaired there. Not completed in August 1945 (she was cannibalized for spare parts for other damaged ships) and scrapped locally. She was to be completed as "Nanshin"
* Also listed as being launched on April 21 1943
** US Navy chronology at Hyperwar indicates that on September 23 1944, she was damaged by a mine laid by USS Bowfin (SS-287) on January 29. It has no record of an attack on this ship on September 21. The position is roughly the same 03° 37' S-116° 25' E, off the southeast tip of Borneo.

Design Nankai Nanshin
Displacement 2400 t 2200
Crew 120
Dimensions 88 x 12,7 x 4,2 m
Armament 2 x 75 mm
2 x 40 mm
4 x 120 mm/45
8 x 25 mm
3 x 80 mm allocated
4 x 25 mm
Mines 80*    
ASW 25 depthcharges    
* I have also found 160 mines

Propulsion details
Machinery 2 Enterprise diesels
Performance 4800 hp
Shafts 2
Max Speed 18 - 20 knots
* Two diesels were under construction at Busch Sulzer in St. Louis, USA in April 1941

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