Optimization of degaussing coil currents for magnetic silencing of a ship taking the ferromagnetic hull effect into account

This paper presents an efficient methodology for optimizing degaussing coil currents in a ship with ferromagnetic hull to minimize magnetic field anomaly underwater. For fast search for an optimum, a magnetomotive force sensitivity formula is adopted. The feature of the method does not require any numerical field analyses to assess an objective function during optimization process providing experimental field data on each coil with respect to the reference magnetomotive force are given. Especially, the shielding effect of the hull on degaussing fields is thoroughly investigated. The validity of the proposed method has been tested with a model ship.