The purpose of the paper is to investigate and to evaluate the tools and information that are available and can be used during the preliminary design stages in order to determine the propeller induced pressures which have an important impact on ship vibrations and, in the end, on the comfort onboard. The designer is often sandwiched within the process of creating a reliable and performant design and the milestones of the building process. Starting from a practical situation, the necessity of further clarifications leads to more detailed evaluations, which could be useful for the preliminary design perspective. The application has been carried out for a double ended passenger car-ferry. The importance of the influence exerted by the wake field on the level of propeller induced pressures and, as a consequence, on the level of vibrations is evaluated and discussed.