Collision risk considering the international regulations for preventing collisions at sea, 1972

For the safety and cost reduction in the navigation, the automatic and intelligent system has been developedfor the vessel, and the most important factor in the system is to decide the collision risk exactly. In thispaper, we propose an advanced collision risk decision system for collision avoidance of the system. Theconventional researches using DCPA and TCPA for calculating the collision risk have a problem to producea same collision risk regardless of bearings for the ships, if they are located in the same distance from ownship. To solve this problem, in addition to DCPA and TCPA, we introduce the factor of VCD(variation ofcompass degree) and constant, CR which derived from COLREG72(International Regulation for PreventingCollision at Sea, 1972) for evaluating the collision risk including even the burden of own ship navigator dueto the encountering angle of each vessels. We decided the collision risk legally by the rule considering therelative situation of vessels. And therefore, the proposed system has two advantages, of which one is toproduce more detail collision risk and another is to reflect the real underway situation in conformity with therule.Key words : DCPA, TCPA, VCD, CR, Collision risk, Colreg 72