Estimating the Heading of Overtaken Vessels by Side Passage Lights

Abstract

Current stern lights can be used during night lookout to gauge the presence of an approaching vessel, but since the light emission range of the stern light is wide at 67.5° on each side, it is difficult to estimate the direction of travel of vessels with these types of stern lights. This study aims to investigate more effective ways to determine if a vessel is approaching, and utilized a questionnaire survey to see if the introduction and expansion of side passage lights, which are currently used on Ultra Large Container Vessels (ULCVs), would solve the problem of the current stern lights. Analysis of the survey results discovered that these side passage lights contribute to a more accurate estimation of the approximate heading in nighttime overtaking conditions, although the accuracy is lower than that in the daytime. Furthermore, based on the results of the questionnaire, if side passage lights are widely adapted, it is unlikely that confusion will arise in the future, even if side passage lights are widely used by other vessels besides container vessels.