The main engine of the ship is a complex technical object, which provides propulsion of the screw and ensures the safety of a ship at sea. It consists of a number of control systems such as lube oil temperature control, temperature control of the cooling water, fuel viscosity control or adjustable speed control of the main engine. Each of the main propulsion control system affects the safety of the ship. Continuous automation systems are built with standard transducer of measured quantity, the controller and actuator. The actuator is responsible for the direct setting of the size of the control object. The actuator is connected to the control valve and the actuator position change translates into a change in the flow rate of the working medium. Thus, the operating element is required to operate in the linear characteristics of the standard signal range. From the other hand, the control valve provides flow characteristics linear or of equal percentage. This control principle of medium flow is used in various control systems. The actuator of the control valve is always equipped with a positioner, which corrects errors in the position of the valve relative to the input signal. The presented design of the motorized valve is an analog system. Using the technique of converting multiple digital signal causes the system complexity and predisposition to damage. Eliminating the intermediate elements can improve the quality control and system safety. Then it is beneficial to have a design of the operating element based on the direct digital processing unit. The aim of paper has been to present design of the valve actuator, which completely abandons the digital-to-analogue convertor. The new design should increase the level of security of the system and quality control. The design layout is presented in the article. The new actuator is on-off valves, which control, directly from the digital bits, the form of the output signal. The control signal may use the control algorithms to be used or developed individually to the actuator design.