瀬戸内海潮流データベースと航海計画立案支援システム

Abstract

There are many inland seas where have international and domestic sailing routes in the world. They have complicated lay of the land and current. We propose Support system for Saving HOurs under Way (SSHOW), that utilizes current at these inland seas. The SSHOW bears the least fuel consumption of ships. The least fuel consumption realizes the preservation of natural environment at these inland seas. In this paper, the objective sea area is the Inland Sea of Japan (ISJ). The width of ISJ is 10 to 30 miles toward North and South, and 240 miles toward East and West. The ISJ has about 3, 000 islands, which are scattered, and the current is complicated. Besides, main sailing routes exist in the ISJ. The estimation of current directions and speeds in the ISJ is generally to carry out by using the Tide Tables of Japan Maritime Safety Agency (JMSA). 13 standard points and 212 calculation points for current are prepared in the ISJ. However, they can not calculate the current velocity of optional points in the ISJ. For supplement these lack, JMSA publishes Current Figures of each water area in the ISJ. Current database was prepared by utilizing the Current Figures. The current database is made from navigational information and geographical information, and they are piled up together in the database. The SSHOW can estimate the current velocity of optional points at optioanl time in the ISJ by using the current database. When sailing route and departure time are input the SSHOW, the hours under way are calculated in accordance with the sailing route. The SSHOW recommends the optional departure time in this day for shortest hours under way. The effective of the SSHOW was confirmed by making comparison between hours under way of actual ships and output of the SSHOW.