Quantitative Analysis of Collision Avoidance Actions Timing for Stand-on Vessels

The collision avoidance responsibilities of both vessels in two-vessel encounters are defined in COLREGs. When the give-way vessel and the stand-on vessel are identified, it may happen that the give-way ship does not effectively take substantial actions in time for some reason. This way, if a collision happens, the stand-on vessel is still responsible for not taking any actions according to the rules. Since there are only descriptive requirements for the actions of stand-on vessels, it is difficult for officers to accurately understand the reasonable collision avoidance actions timing. From the perspective of ship navigation safety, this paper analyzes the action timing for stand-on vessels, combining the phases of collision accident development. By defining the ship domain at different phases and the possible actions, the earliest and latest timing for standon vessels to take action are both quantified. Finally, based on the simulation results in crossing situations, the factors affecting the timing are analyzed, and the corresponding suggestions are proposed. The research results provide a theoretical basis to further study the behavior of stand-on vessels in the context of intelligent collision avoidance, and practical references of the collision avoidance actions for stand-on vessels.