ABSTRACT
Naval ship magnetic deperming is a method to keep ship’s safety against weapons equipped with magnetic sensors, such as sea-mines, and has been operated by several navies. Boats were built with wood when people tried for the first time to go over water in any place in the world. Silencing of ship magnetization is implemented by degaussing and by deperming treatment. Deperming is a treatment to reduce remnant magnetization of ship by cable temporally set outside of ship during the treatment. Deperming is to reduce remnant magnetization of ship, which is expressed by permanent magnetization of ship. Deperming has been conducted by navies around the world and magnetic field to impose on ship is decided by each navy from the data obtained on their ships and is kept confidential. HTS deperming of ship by seabed coil needs power supply in the levels of tens of kW class and some extra power for refrigeration by liquid nitrogen and liquid hydrogen.
