Smaller vessels normally have only one engine and need to run it continuously. Larger vessels typically have two engines.
With a Corvus ESS on board, a vessel can use battery only during fishing and other operations that have low power requirements. For operations requiring more power, the vessel can run the diesel electric. During diesel-electric operation the batteries are charged by the generators, making the vessel ready for all-electric operations later.
Installing batteries to optimize the energy consumption on fishing vessels typically reduce fuel consumption by 25% and emissions by 25-40% . Other benefits are silent and smooth operations and increased safety as the battery serves as UPS in case of emergency.