Process for compensating local magnetic perturbations on ferromagnetic surfaces

This paper addresses a practical application for the compensation of a local magnetic perturbation in a ship in the near field region. The process will avoid expensive deperming techniques usually applied to ships to treat magnetic anoma- lies. The technique includes a new system to construct magnetic maps on flat ferromagnetic surfaces. Once the mag- netic maps are obtained, a new system is proposed to evaluate and locate local magnetic perturbations. Once the local perturbations are located, they are compensated by local degaussing coils. The new technique has been applied to the detection of local magnetic perturbations in four naval platforms. Two of them presented important magnetic anomalies, and were successfully detected and corrected by applying the new technique, thus showing its practical value