ModernNavy and CoastGuard Vessels usually have combined propulsion systems using gas turbines@ diesel engines and electric motors as main propulsors. Desired operating profiles demand for individual optimization of the gear propulsion system with respect to efficiency@ noise@ operational flexibility and capital cost. Combined systems are complex and therefore sensitive to dynamic excitation and resonance. To avoid unfavorable dynamic effects@ it is necessary to validate candidate arrangements usingmodern tools like multi body simulation. The paper describes the evaluation process for optimized combined marine propulsion systems and system validation by dynamic simulation.