Properties of virtual safe regions

In the straitened waters in case origin of situation of dangerous rapprochement of courts at the choice of maneuver of divergence surrounding ships and navigation dangers must be taken into account also, that presently possible by an analytical way and is arrived at by bulky and ineffective methods. Therefore, the necessity of development of operative and evident methods of warning of collisions of vessels at sailing in the straitened waters based on application of modern computer technologies is an actual and perspective subject. In the article is specified, that the sign of dangerous rapprochement of ship with a target behaves to basic properties of virtual region, in obedience to which distance of the shortest rapprochement of ship with the target of less set maximum – possible distance of rapprochement, there is the hit of current area of programmatic trajectory of motion of ship in the virtual region of target. It is also marked that distance of the shortest rapprochement of ship with a dangerous target will be equal to the set maximum-possible distance of rapprochement, if direction of current area of programmatic trajectory of motion of ship is tangent to the border of virtual region. It is shown in the article, that to the factors influencing on sizes and orientation of virtual regions, belong, bearing and distance between a ship and target, relation of speeds of ship and target, and also time domain from the initial situation of rapprochement at the following of vessels unchanging by the parameters of motion. In instance where attitude of speed of ship toward speed of target diminishes other things being equal a virtual region changes the form and position, here safe rapprochement can be transformed in dangerous. There is the increase of sector of dangerous relative directions at diminishment of initial distance, that in general case conduces to diminishment of great number of safe courses of ship. It is shown that the change of orientation, form and sizes of virtual region takes place at the change of bearing on a target in the case of unchanging distance and the other parameters of situation of rapprochement. The sizes of virtual region depend on the course angle of ship from a target, thus with growth of course corner is multiplied a virtual region. Thus the sizes of virtual region do not depend on that, whether there is the course angle of side right or port.