ふね遺産 南極観測船「宗谷」の氷海航行能力に関する考察

抄録

　In 2023, the Society of Naval Architects and Ocean Engineers awarded the Antarctic research vessel, icebreaker SOYA a ship heritage award. SOYA is renowned for its contribution to the establishment of Syowa Station and the foundation of the Japanese Antarctic Research Expedition. However, its ice navigability from a naval architecture perspective is not well understood. In this paper, The author estimates the ice navigability of SOYA based on current technology, verifying the accuracy of these estimates using contemporary data, such as the SOYA's navigation records. Continuous icebreaking capability is estimated that SOYA can break ice up to 70 cm thick at 3 knots, which is less than half the thickness that the current Antarctic research vessel SHIRASE can break at 3 knots (150 cm). According to the latest ice class rules by the International Association of Classification Societies, hull plating is generally PC5 to PC7 in strength, but in some hull areas it is below PC7. This indicates that the structural strength is much lower than that of SHIRASE (equivalent to PC2). Although no serious navigational accident occurred, significant damage was observed at the joints between the cast steel components and the main hull in the bow and stern areas, as well as in the bulge sections.