The Japanese Antarctic research icebreaker makes a voyage in Antarctic severe ice condition every year for the transportation of cargoes and scientists to Japan's Antarctic basin and for the Antarctic expedition. The new icebreaker Shirase took her maiden voyage to the Antarctic from November 2009 to April 2010. She had encountered with extremely severe ice conditions including 4 m or even thicker ice and broke through such an ice field by her expected icebreaking capability with some technologies such as a water flushing system.
Japanese new icebreaker Shirase was completed in May 2009, and took her maiden voyage to support the 51st Japanese Antarctic Research Expedition (JARE51) from November 2009 to April 2010. Syowa station, Japan's stronghold for the Antarctic expedition, is located on the East Ongul island (69o00'S, 39o35'E) in Lutzow-Holm Bay well-known for its very severe ice condition. It is not rare case that the ice thickness of fast ice is over 3 m and it is covered with snow of 1 m thick or more in Lutzow-Holm Bay. An icebreaker should break through that ice field by many times of ramming. Through the voyage experiences of the former icebreakers in Lutzow-Holm Bay, the importance of ramming performance to keep the voyage schedule had been recognized. Several effective technologies were introduced into the Shirase to improve the icebreaking capability. In her maiden voyage, the Shirase encountered with one of most severe ice conditions in the Japanese icebreakers' Antarctic voyages for the last fifty years. The ice thickness of multi-year ice was more than 4 m and it was covered with compacted snow of 1 m thick or more. She broke through the severe ice field by ramming operation, making good use of some technologies such as the water flushing system for improvement of icebreaking capability.
