Ship’s de-perming process using coils lying on seabed

A ship built from ferromagnetic steel disturbs the uniformity of the Earth's magnetic field.Changes of ship's signature are due to the magneto-mechanical interaction of the hull with the Earth's magnetic field.The ship's magnetic field can be detected by a magnetic naval mine.For this reason, the vessel has to be demagnetized.There are several methods of ship's de-perming.The results of experimental and computer simulations of the ship's de-perming process using coils lying on the seabed are presented in this paper.The simulation of the de-perming process with a hysteresis model of ship's steel was carried out in Opera-3d 18R2.The laboratory experiments were carried out using a physical ship's model, several Helmholtz coils, magneto-resistive sensors, etc.The experiments and computer simulations have shown that ship's de-perming with coils lying on the seabed is possible.The values of coil currents are over dozen times greater than those used in the standard method.