In this graduate thesis the main engine propulsion design variants are analyzed for patrol ship of autonomy of 3000 nm and minimal cruise speed of 20 kn. The task of the graduate thesis and the basic characteristics of a similar ship have been described in the introduction. In the second section different types of propulsion system have been considered alongside their basic characteristics (CODLAD, CODAG, CODAG propulsion system). In the third section the most economical propulsion system has been chosen (CODLAD). Furthermore, the braking power of the machine and the achieved speed of all system has been calculated. All calculations were made according to „SKLAD“ series of semi-displacement form. In the fourth section there is calculation of a feature of the chosen variant of the project, CODLAD system. The calculation of the entire machinery and it´s equipment has been described in details. The fifth section presents the model of a ship that was modeled in „Rhinoceros“ program. Moreover, in this section all of weights on a ship, material and armament selections have been defined. In the sixth section the stability computation in the „Maxsurf Stability“ program is introduced. The calculation is made for easy, standard and full deplasman as well as damaged and undamaged space. Unsinkability for two and three neighbouring spaces has been calculated. Seventh section is the computation of seaworthiness in the „Maxsurf Motions“ program. In this section the speed decline on wavy sea, strikes of the bow and green water on deck has been analyzed. The eighth section displays the examination of the strength of the chosen project´s variant by finite element method. Examination is conduced in „Femap“ program. Section of the ship around it´s main rib is analyzed, and the structural solution is being made. Effect of hydrostatic pressure on ship plating is observed. At the end of the thesis the conclusion is made.