The increase in global trade is driving growth in both the size and number of ships. However, this increased demand is leading to greater contributions from shipping to air pollution. This is leading designers and operators to propose and adopt novel powering and propulsion systems. However, there is a challenge with assessing the actual benefit from using a certain retrofit technology or changing the operating conditions of their ships, this may be addressed using numerical simulations. This paper presents a time-domain one-degree of freedom ship simulator implemented in MATLAB/Simulink to enable designers to predict the performance of ship propulsion system during voyages. The proposed simulator is used to assess the effectiveness of three different EEDI and SEEMP measures suggested by IMO to increase ship’s propulsion system efficiency which are: voyage execution, slow steaming, and hybrid electric power and propulsion concepts using fuel cells. The developed simulator can be used for further studies and more elements are planned to be added to the ship simulators to make it more generic and capable of testing more propulsion configurations options.