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Japanese icebreaker Ōtomari
IJN ice breaker ODOMARI in 1921.jpg
Ōtomari in November 1921 at Kōbe
Career (Japan) Japanese Navy Ensign
Name: Ōtomari
Namesake: Port of Ōtomari
Ordered: 1920 Fiscal year under the Eight-eight fleet plan
Builder: Kawasaki Shipbuilding Corporation
Laid down: 24 June 1921
Launched: 3 October 1921
Completed: 7 November 1921
Decommissioned: 15 September 1945
Fate: Scrapped between October 1949–March 1950.
General characteristics as built
Type: Icebreaker
Displacement: 2,330 long tons (2,367 t) standard
Length: 60.96 m (200.0 ft) pp
Beam: 15.24 m (50 ft 0 in)
Draught: 5.55 m (18 ft 3 in)
Propulsion: 2 × triple expansion reciprocating engines, 5 × scotch boilers
2 shafts, 4,000 shp
Speed: 13 knots (15 mph; 24 km/h)
Range: 4,000 nmi (7,400 km) at 14 knots
Endurance: Fuel: 500 tons coal
Complement: 101
Armament: as built
1 × Armstrong 3 in L/40 gun
In the Pacific War
1 × Armstrong 3 in L/40 gun
2 × Type 96 25 mm AA guns
6 × Type 93 13 mm AA guns
some depth charges

The Ōtomari (大泊?)[1] was an icebraker of the Imperial Japanese Navy (IJN) serving during the 1920s through World War II, the only ship of her class. She was an only icebreaker as warship in the IJN.


Russian icebreaker Dobrynya Nikitich

Ōtomari was planned as one of the Kamoi-class oilers under the Eight-eight fleet plan at first. However, Nikolayevsk Incident changed her future. IJN was not able to dispatch their warship to Nikolayevsk which froze, because they did not have an icebreaker. All Japanese civilians were killed by terrorist in this incident. Japan was afraid that this dire disaster occur once again, because the Russian Civil War continued in this time. Japan built only lead ship about the Kamoi-class oiler. Other 5 vessels, they rearranged a budget and built three oilers (Ondo-class), one food supply ship (Mamiya), and one icebreaker (Ōtomari).
As for Japan, the icebreaker architecture was the first experience. IJN began by observing a sample of neighboring various countries, They decided to make a model of the Russian icebreaker Dobrynya Nikitich. The IJN hurried work of Otomari, because they wanted her until Winter 1921, she was completed from a building start in only four months.
She was assigned to Ōminato Guard District and took northern patrol duties, and continued being active for her life.
In World War II, the IJN planned her succeeding ship Esan (恵山, Project Number J23, 6,800 tons standard) under the Kai-Maru 5 program in 1942, because Ōtomari was old and small, however, Esan was canceled in 1943.


File:HIJMS Otomari-1948.jpg

Ōtomari in Yokosuka, 1948

Ōtomari acted in Sakhalin, Kuril Islands and Sea of Okhotsk between all time except maintenance. In July 1945, she sailed to Yokosuka Naval Arsenal for maintenance. However, she was not able to take maintenance because Japan was surrendered. Japan was going to employ her as repatriation transport, however, it was given up, because her boiler was worn out. She was scrapped in March 1950.


  1. 30 May 1921, Notice No. 104, Named one auxiliary vessel., Minister's Secretariat, Ministry of the Navy.


  • Ships of the World special issue Vol.47 Auxiliary Vessels of the Imperial Japanese Navy, Kaijinsha, (Japan), March 1997
  • The Maru Special, Japanese Naval Vessels No.34, "Japanese Auxiliary vessels", Ushio Shobō (Japan), December 1979
  • The Maru Special, Japanese Naval Operations in WWII No.111, "Imperial Japanese Naval Vessels in postwar", Ushio Shobō (Japan), May 1986
  • Senshi Sōsho Vol.31, Naval armaments and war preparation (1), "Until November 1941", Asagumo Simbun (Japan), November 1969
  • "Rekishi Gunzō".  History of Pacific War Vol.37, "Support vessels of the Imperial Japanese Army and Navy", Gakken (Japan), June 2002, ISBN 4-05-602780-3

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