Judging Vessel Courses via the Horizontal Distance Between Two Masthead Lights

Abstract

The authors' previous study demonstrated that vessels which had an extremely short horizontal distance between two masthead lights, even in crossing situations, judged their own “Head-on situation” course by observing other vessels at night. In light of the conclusions from the previous research, this paper focuses on an analysis of a questionnaire survey for pilots, ocean-going officers, domestic officers, small boat operators and fishing boat operators. The contents of the questionnaire survey investigate ① “What length of the horizontal distance between two masthead lights are required for reducing the chances of misreading another vessel’s course?” ② “Do you know how to observe an extremely short horizontal distance between two masthead lights of another vessel?” ③ considered feasible measures. The results suggest that ① as the horizontal distance between two masthead lights widens, the number of people who judged another vessel’s course nearly 90 degrees angle of a “Crossing situation” increased; ② many people did not know how to correctly observe the vessel as it has an extremely short horizontal distance between two masthead lights at night, ③ it is important to introduce “how to see vessels with extremely short horizontal distance between two masthead lights (e.g. the Japan Maritime Self-Defense Force ship, the Japan Coast Guard vessel, the marine research vessel and the heavylift vessel) at night” to mariners in Japan and/or abroad. After a background review of this issue, this paper will analyze the data from the questionnaire results, and finally discuss conclusions and offer some suggestions for measures to correct any problems, as well as directions for future research.