Study on Underwater Electric Fields of a Dipole Moment in Shallow Water

We studied a method for estimating electric conductivity of the seabed which was necessary for the calculation of electric dipole moment of a boat from underwater electric field. Taking a model of a single electric dipole in a conducting medium with two boundary planes of the sea surface and the seabed, we calculated electric conductivity of the seabed using the measured underwater electric field of a direct current electric dipole. The measurement was conducted with three-axis electric field sensors set on the seabed at a depth of 16.7 m. The underwater electric fields of a tugboat were measured in the same manner as that for a direct current electric dipole. The conductivity of the seabed was calculated using the underwater electric field signature of the tugboat and the result agreed with that obtained from the direct current electric dipole.