Database concept for static navigational information

When ships are under way and before leaving ports, their captains and officers (ship navigators) accumulate all sorts of navigational information necessary for safe and efficient ship handling. The navigational information is divided into two categories. One is `dynamic navigational information´ and the other is `static navigational information´. The former is real-time information about ships and their environment, which changes every moment at sea. The latter are characters, symbols, lines and colors information of hydrographic publications. Although the static navigational information is fundamental to both categories, it is retrieved in the publications, such as nautical charts, distance tables, sailing directions and so on, by manual processing of the ship navigators. For this reason, the authors have been studying an automatic retrieval system implemented on an engineering workstation for the static navigational information restricted to the nautical charts, sailing directions and distance tables. This paper presents a prototype the authors have developed recently. The system has two sets of database that include the attributes of more than one thousand Japanese nautical charts in waters adjacent to Japan, and `Seto Inland Sea´ sailing direction. Seto Inland Sea is a narrow and long area, which has the heaviest sea traffic in Japan and the world. Hence, it was/is an arduous task to fix a course on the next voyage. By introducing the developed system, the job can be changed into a rather easy operation of pointing by a mouse, which inputs the main points of altering course on the next voyage in the general chart presented on the graphic display