The original concept of the energy test during continuous fishing of a Baltic cutter lasting 100 working days at the fishery has been presented in the paper. The test will enable the calculation of the fuel consumption and the operating efficiency of the energy system. The calculation models which are made in the paper take into account the actual realizations of energy and trawling systems, operating conditions of ships and parameter values characterizing the operation of all devices under consideration. The test may be used to evaluate the design solutions of ships at the design stage as well as the ones already in use.