Fuel efficiency improvements and integration of low or zero emission sources into shipboard power systems have recently become a global trend in the maritime industry. In this context, hybrid ship power system architectures with diesel-electric generators and battery energy storage systems have drawn attention as an attractive solution to increase fuel efficiency and thereby reduce emissions. In this arrangement, the battery energy storage system is used as a buffer to decouple the load dynamics and thereby allow the engine to operate at its optimal operating range. The aim of this study is to assess the fuel saving that can be achieved with this arrangement in an electric ferry. Load profile of an actual ferry, operating between two terminals, is used to estimate the fuel-saving. Results of this study showed that 4.65 L of fuel can be saved in a round-trip by avoiding low efficiency operating regions of the diesel engine.