The application of computers in ship design and hydrodynamics is playing an increasing role today. The development of computers has created the possibility to use their power for complex calculations of computational fluid dynamics (CFD - Computational Fluid Dynamics) such as solving a large number of partial differential equations. Using CFD methods in design can provide more information about a particular problem and can greatly reduce costs. In this thesis, the hydrodynamic performance of a RoPax ship with installed water jet propulsors is analyzed. The first part of the thesis describes the problem and presents the possibilities of solving different approaches, analytical, empirical and numerical methods. An appropriate CFD procedure was defined and the validation of the simulations was performed by comparing the numerical results with the known experimental results. CFD simulations were made for several different geometries of the ship's shape, both for the geometry of the bare hull of the ship and for the shape of the hull with appendices and openings in the places of possible placement of selected water jet propulsors. Next, the several flow simulations with installed water jet propulsors are made, and the characteristics of propulsors in the field of fluid flow are presented. The influence of their installation on the hydrodynamic performance of a given ship is analyzed. In conclusion, a form change proposal is given for the purpose of more efficient fluid flow to the inlets of water jet propulsors.