On an Experiment of Collision Avoiding Behavior by Radar Simulator and a Collision Avoiding Seamanship

Abstract

This paper deals with the experiments on the Collision Avoiding Behaviors by experienced navigators for the target approaching from side in the restricted visibility. The experiments were carried out on the condition that (1) Own ship was proceeding at 15 k't (S/B Full ah'd) in the ocean, (2) Target ship's initial position were at 10 miles of port side, and time to collision were 45 minutes, (3) Own ship could maneuver with no restrictions. The results of the experiments were as follows. (1) The tendency of altering course were not certain for the targets of forward of abeam. (2) Marked tendency of right turn were observed for of abeam and after of abeam. (3) The distance to the targets of taking action was 5.7 miles, and desired CPA was 1.8 miles (mean value). The effect of right turn for the target of near abeam is generally not positive nor remarkable, hence, the author propose a method to clear these encounters. The method is to shift the relative motion line parallel to original course of own ship. The boundary of this method is that the speed is less than the product of own speed and secant of relative bearing.