ABSTRACT
Collision avoidance is one of the most important operations in ship navigation. A fast and effective assessment of the navigating situation and decision on adequate actions are essential for the safety of the ship itself and all the surrounding ships. The regulations on the role assignment introduced in the International Regulations for Preventing Collisions at Sea (COLREGs) are studied. The paper addresses the possible conflicts between Rules 12 and 15 when information about the ship types is not complete or is assessed differently by the two ships involved in the encounter situation. With respect to the Rule 12, algorithms of determining the wind direction on ships and the ship to windward are introduced, so that the role assignments using Rules 12 and 15 can be established automatically. The results derived from the two rules are compared and the possible conflicts are demonstrated. Possible ways of dealing with such conflicts are also discussed.
