This paper presents an experimental technique to accurately separate a permanent magnetic field and an
induced one from the total magnetic fields generated by a steel ship, through compensating for the Earth’s
magnetic field. To achieve this, an Earth’s magnetic field simulator was constructed at a non-magnetic
laboratory, and the field separation technique was developed, which consisted of five stages. The proposed method was tested with a scaled model ship, and its permanent and induced magnetic fields were successfully extracted from the magnetic field created by the ship. Finally, based on the separated permanent magnetic field data, the permanent magnetization distribution on the hull was predicted by solving an inverse problem. Accordingly, the permanent magnetic fields generated by the ship can easily be calculated at any depth of water.