Exergy flow motion insight and analysis of plant requirements for a typical conventional LNG carrier with Rankine regenerative feed water heating steam cycle is given in this paper to clarify and distinguish auxiliary flow streams from the useful ones. Auxiliary flow supports the plant operation, but reduces exergy efficiency by certain amounts. Main boilers exergy flow streams are divided into two major groups: superheated and de-superheated flow stream consumers. A plant run test was carried out by varying main shaft revolutions to collect required thermodynamic data at various plant locations. In the presented marine steam plant is explained exergy flow streams for considering components and flow streams ratios of particular plant components. It is detected and explained the points of excessive auxiliary stream flows consumption and recommendations for possible reduction in saving auxiliary power or steam consumption are given.