The round-the-world transition of m/v Katherine ship is considered. The aim of this work is to minimize the Energy Efficiency Operational Indicator (EEOI) of the vessel, and, accordingly, to minimize the ship's fuel consumption and carbon dioxide emission depending on the parameters of sea transition: Vs, mass of transported cargo, and the distance of the passage. For specifically selected ship power plant (SPP), the parametric dependence of Vs and fuel consumption on the share of used power is determined by calculation method. The Energy Efficiency Design Index (EEDI) is determined by the model given in Resolution MEPC.212(63). The EEOI is determined depending on the ship fuel consumption, the carbon concentration in the ship’s fuel with the main parameters accepted for transition Vs, transported cargo mass , the sea passage distance . Calculation studies are conducted in a wide range of sea transition parameters – transition distance within 200 to 2,800 nm, the Vs from 0.01 to 24.0 knots, cargo mass ranging within 4,000 to 70,000 tons.