The aims to develop innovative technological solutions, which intend to reduce greenhouse gas emissions and contribute to overall energy savings on ships, are continuously under consideration by shipowners and shipbuilders around the world. In order to reduce the energy consumption of the largest energy consumer on board, Energy Saving Devices (ESD) have been developed, and thus represent a promising option for achieving this goal. ESD devices improve propulsion efficiency based on their hydrodynamic shape that affects the operation of the propeller. In this thesis, the dynamic characteristics of such a device i.e. a Pre-Swirl Stator (PSS) have been analyzed. On the example of an asymmetric pre-swirl stator for a cargo ship currently being developed by the South Korean shipyard Hyundai Heavy Industries Co., Ltd, the suitability of installing such device from the viewpoint of vibrations has been shown. The provided dynamic analysis has been done by comparing the vibration frequencies caused by the operation of the propeller and Vortex Induced Vibrations (VIV) with the natural frequencies of the pre-swirl stator. The analysis of the natural frequencies were calculated by using two different approaches: First, by using approximative analytical equations and second, by using the finite element method on a commercial software NASTRAN. The finite elements model was provided directly by the shipyard. The effect of the fluid added mass is shown by comparing the first few natural frequencies separately for the pre-swirl stator in air and water.