The screw propeller of a ship generates thrust to make it moving. As a propeller rotates, it draws fluid into itself from the surrounding area (slipstream). The propeller produces two types of flow behind it, accelerated and circulated flows. Some of the energy from the ship engine is lost in the accelerated flow behind ship as a jet wash. The kinetic energy losses in the slipstream propeller captured by a turbine called the propellerturbine system. This composed screw propeller of a vessel (the main propeller) and a vane turbine that is the area of vanes located inside the wake of the main propeller. It recovers the energy generated by the main propeller pushing water back out (which would be otherwise wasted behind the main propeller) and hopefully enhancing the efficiency of the main propeller. The influence of vane turbine on the performance breakdown of single screw ships were analyzed by using 5 (five) ships. Ship powering was calculated by using DESP Code 10 software. Thrust and power of vane turbine were calculated by applying actuator disc theory. Although the vane turbine affected speed loss of the ship, the power efficiency gained to be found always positive. Vane turbine is suitable as an energy saving device of the single screw ship.