The Monaco Energy Boat Challenge (MEBC) is an international competition promoting innovation in sustainable marine propulsion. In the endurance race, one of its main events, teams aim to complete as many laps as possible under a strict energy budget. This work presents a control strategy based on the Equivalent Consumption Minimization Strategy (ECMS) for a hybrid catamaran powered by a lithium-ion battery and a PEM fuel cell. A quasi-static powertrain model is used to simulate the system’s behavior and calibrate optimal equivalence factor (lambda) values via a bisection algorithm, accounting for varying speed profiles and hydrodynamic drag conditions. This calibration process results in a lookup table-based controller, enabling real-time implementation of ECMS.