SENSUI-BOKAN!

Stories and Battle Histories of the IJN's Auxiliary Submarine Depot Ship

20 August 2020

By Bob Hackett, Sander Kingsepp and Peter Cundall

Discussion & Questions


(Chogei by Yuki Takeshi)
In the Fall of 1941, the IJN requistioned five merchant ships from their owners for conversion to submarine depot ships. These were HEIAN, YASUKUNI, NAGOYA, RIO de JANEIRO and SANTOS MARUs. All five were in operation in as submarine tenders in 1942. HIE and TSUKUSHI MARUs were requistioned in 1942 and 1943 respectively.

NAGOYA MARU was rerated a transport in 1942 while HIE and SANTOS MARUs were rerated transports in 1943. TSUKUSHI MARU was rerated a transport in 1945. Later, she was used as a repatriation ship by the Allies.

In 1945, auxiliary gunship NACHI MARU was converted to an auxiliary submarine depot ship for midget submarines. She survived the war.

BOGOTA and QUITO served as tankers and supply vessels for German U-boats operating in the Pacific and Indian Oceans. QUITO was sunk by an American submarine in April 1945. After Germany’s defeat in May 1945, the Japanese seized BOGOTA and interned her crew. She then served the IJN as a supply ship.

Japanese Auxiliary Submarine Depot Ships: Tabular Records of Movement (TROMs)

(Submarine Depot Ship Classes link to specifications summaries)

Heian Maru Class

Heian Maru (revised 10/19/2018)
Hie Maru (revised 9/1/2017)


Yasukuni Maru Class

Yasukuni Maru(revised 5/20/2017)
Nagoya Maru Class

Nagoya Maru (revised 8/6/2016)

Rio de Janeiro Class

Rio de Janeiro (revised 4/19/2015)
Santos Maru Class

Santos Maru (revised 10/19/2018)

Nachi Maru Class

Nachi Maru (revised 8/20/2020)

Tsukushi Maru Class

Tsukushi Maru (revised 6/2/2018)

Bogota Maru Class

Bogota Maru (posted 5/15/2010)

Quito (posted 5/22/2010)

Bibliography of Sources

About the Authors

Bob Hackett is a military historian and researcher. Retired from the United States Air Force and later from the aerospace industry, he resides in the United States.

Sander Kingsepp of Estonia is also a military historian and researcher. A talented linguist, Sander's translations of Japanese source materials have added immeasurably to these TROMs.

Peter Cundall is a maritime historian and researcher who specializes in merchant ships. He works in the marine industry and resides in Australia.

Questions to the authors concerning these TROMs should be posted on the Discussion and Questions board.