A method in a corrosion protection system for protecting a first and a second metal part of a marine construction is provided. The method includes controlling electrical currents through electrical circuits, including respective anodes, the respective metal parts and an electrolyte, at least partly based on measured electrical potentials of the respective metal parts with an reference electrode as a ground reference. The method further includes repetitively performing the steps of controlling the electrical currents so as to be reduced or eliminated, measuring the electrical potentials while the electrical currents are maintained reduced or eliminated, and, after measuring the first and second electrical potentials, controlling the electrical currents so as to be increased or reestablished.