For the analyzed LNG carrier with Rankine regenerative feed water cycle, energy analysis is presented. The intention was to determine auxiliary flow streams from the useful ones. Auxiliary energy flow supports plant operation on the one side, but reduces overall efficiency on the other. Steam generators energy streams are divided into two major groups, for the main and auxiliary stream consumers. The steam system test was performed by varying main propulsion shaft revolutions. The required thermodynamic data are collected at various steam system locations. For considered plant energy flow streams components are explained and analyzed. In this paper the recommendations for possible energy savings for the mentioned propulsion plant are proposed.