Graphical Tools to Facilitate the Selection of Manoeuvres to Avoid Collision

Graphical tools have been proposed to facilitate the selection, evaluation, and correction of anti collision actions in situations with moving and stationary obstacles, assuming that such situations are not extreme or ordinary with sailing vessels and that the target movement parameters are constant or their upcoming change is known. The choice of evasive combined Z-manoeuvre (both course and speed change at one point and return to the original values of these parameters at another point) and one combined action (both course and speed alteration at the selected point) were considered. The graphical tools developed contain diagrams, showing eight zones of actions, and special marks of targets at the moment of their closest approach to the own ship. In view of the COLREG and good seamanship, these zones were arranged in order of application priority. The results of the enumeration of a representative discrete set of possible manoeuvre variants were used to construct the diagrams.