The Research Of Avoidance Effects By Changing Course And The Best Action Time

Actiong time is an important research direction in the field of collision avoidance. It has an important significance to enhance the safety of the ship and improve economic efficiency, at the same time, it can provide theoretical basis for ship collision avoidance expert system and realize the ship automatic collision avoidance. At present, there are many experts and scholars studying on the action time.The research works of this paper can be mainly demonstrated in the following aspects:1) This paper has a more comprehensive summary of research results at home and abroad on the action time. It points out some deficiencies exist in the current study and the direction for this study by conducting research and analysis on these studies.2) By studying on the ship avoidance mechanism, the paper builds the ship motion mathematical model of ships avoidance. The model has four main factors that affect the DCPA changes, that is the distance of two vessels, bearing of the approaching vessel, the speed ratio and the course changes;3) According to the model, the paper draws the curves that DCPA changes with course changes and the curves of the relationship between two ships distances and course changes in different conditions;4) It gets the influences of the various factors on DCPA change and action time through the comprehensive analysis of curves.5) Combining with the International Collision Avoidance Rules at Sea, the encounter situation were divided as four situation as follow:the vessel come from forward of s the starboard abeam, the vessel come from abaft the starboard abeam, the vessel come from forward of the port abeam, the vessel come from abaft of the port abeam;6) In the previous basically, the paper has a comprehensive consideration of various factors on action time. Then, it gets the distance of safety point approach (DSPA), as well as the critical value of the rate of course(Critical CoRat). Build the best action time model for the give-way vessel by using the DSPA, Critical CoRat and the action time curves.The study can provide some reference for the crew to make decisions for collision avoidance at sea and provide some theoretical basis. for collision avoidance decision research.