Safety First—A Critical Examination of the Lights and Shapes in COLREGs

Abstract

According to The International Regulations for Preventing Collisions at Sea, 1972, ships can only determine their collision avoidance responsibilities in accordance with the rules of “Conduct of Vessels in Sight of One Another” if the dynamic and category of the target ship is identified to be using lights and/or shapes during encounters at sea. Then, appropriate actions can be taken, and the effectiveness of the collision avoidance actions can be checked during the subsequent maneuvering process. In order to analyze and solve the problems related to lights and shapes and to adapt to the development of ship size, speed, and intelligence, this paper firstly reviews the development history and revision process of lights and shapes. Furthermore, it explains the collision avoidance responsibility of ships in sight of one another, analyzes the role of lights and shapes in the collision avoidance process, and summarizes the lights and shapes displayed by different categories of ships. Next, through qualitative and quantitative analysis, the relationship between the visibility distance of lights and shapes and the timing of ship avoidance actions is examined. Finally, the paper points out current problems related to lights and shapes, including: (1) non-uniform visibility distance of lights, (2) insufficient visibility distance of lights, and (3) small size of shapes, and proposes solutions to these problems from theoretical and practical perspectives, including: (1) unifying the visibility distance of masthead light, sidelights, and sternlight to 6 nautical miles, (2) unifying the visibility distance of the sternlight to 3 nautical miles, and (3) unifying the diameter size of shapes and the vertical distance between shapes to 1.8 m.