In this work, a multidomain simulation model for a complex marine hybrid powertrain was developed and a control strategy was implemented to optimize the powerflow. The increasing demand for sustainable marine transportation has led to a growing interest in hybridization of marine systems. The combination of traditional fossil sources together with renewable ones has a great potential impact in improving the overall system efficiency, reducing emissions and fuel consumption. Owing to the availability of a reversible energy storage system (usually a combination of batteries and super-capacitors) and one or more electrical motors that can support the thermal engine, hybrids can operate with greater flexibility.