The book gives a clear idea about the concept of gas turbines, thermodynamic basics of the turbine theory. It includes classification of gas turbines, working principle, structure feather, application and designing approaches of gas turbines. The readers will understand easily the power system for ships since there are a lot illustrations and instruction for each of equipment. It also introduces the thermal calculation of gas turbine unit, different structure feather of compressor, combustion chamber and turbine. It gives the way to increases the efficiency of the unit, design and operation of the gas turbine parts. The combined marine power plant with gas turbine is discussed and advantages and disadvantages for each type unit is discussed too.