The goal of this paper is to discuss the problem of avoiding collisions at sea from the perspective of an evolutionary process and representation in this problem the risk of collision. In an evolutionary method (EP/N Evolutionary Planer Navigator System) of generating paths of the ship in partially-known environments is presented. The evolutionary process which searches for a near-optimum trajectory in a collision situation takes into account a time parameter and the dynamic constraints, which treat to the risk of collision with meeting strange ships. The ship domain as a risk of the collision - shapes and dimensions of dynamic constrains depend on assumed safety conditions.