The aim of the work is to determine the conditions of optimality in the task of plotting the course of the vessel and the operation of divergence of vessels in conditions of intensive navigation. The need for such work is dictated, firstly, by an increase in the intensity of shipping and, secondly, by the emergence of autonomous ships and transport systems, the traffic control algorithms of which obviously require an optimal approach. The criterion of optimality in problems of this class is the expected risk, one of the components of which is the risk of collision of ships. Based on the analysis of methods for constructing ship divergence algorithms, the task is to find a control algorithm that delivers the best results for all participants in the operation. This formulation of the task greatly facilitates the forecast of the actions of all participants in the discrepancy and is especially expedient in the case of participation in the operation of an autonomous system or a ship with which no contact has been established. Theoretically, the task belongs to the most difficult class of control problems -optimal control of a distributed dynamic system with a vector -a goal functional [3,5,8,[13][14][15]. The ability to obtain a general solution to the task of optimal ship control makes this study expedient.