Efficient methodology for optimizing degaussing coil currents in ships utilizing magnetomotive force sensitivity information

This paper presents an efficient methodology for optimizing degaussing coil currents in ships to minimize the anomaly of underwater magnetic fields due to the hull magnetization induced under the Earth's magnetic field. To achieve this, first, the shielding effect of the hull on the underwater fields is thoroughly examined. Then, for a fast search of optimum degaussing currents, a sensitivity formula of an objective function with respect to the magnetomotive force is adopted. The feature of the proposed method is that it does not require any numerical field analyses to assess an objective function during optimization process providing experimental field data for each coil are given. The validity and effectiveness of the method has been tested with a model ship.