Modification of the Shaft-Rate Magnetic Field Model Based on Random Sea Surface

The frequency of the ship's shaft-rate magnetic field is between 1 and 7 Hz, exhibiting clear line spectral characteristics, which represent an important signal characteristic of the ship. In order to study the propagation and distribution characteristics of the ship's shaft-rate magnetic field and to create a more accurate model for analysis, this paper employs the finite element method to construct a ship's shaft-rate magnetic field model based on finite elements. This model simulates the random sea surface and analyses the vertical spatial distribution of the shaft-rate magnetic field as well as the attenuation characteristics. Finally, a comparative analysis is conducted using the actual measured data at sea. The findings demonstrate that the finite element model is capable of calculating the spatial distribution and attenuation characteristics of the various components of the shaft-rate magnetic field. When compared to the measured data, the model incorporating a random sea surface can more accurately simulate the shaft-rate magnetic field signal in an actual marine environment than the model with a flat sea surface. This results in an improvement in simulation accuracy from 73.95% to 82.98%.