What do you call the process by which an electrical current is used to neutralize the magnetic field around a ship's hull in order to avoid detection by magnetic sensors?

The ship’s hull which is made of steel acts like a large floating magnet surrounded by an even larger magnetic field. This result to a distortion on the Earth’s magnetic field and the ship can therefore act as a trigger device for magnetic sensitive devices which are designed to detect these distortions. So to reduce the effect of the ship on the Earth’s magnetic field, a degaussing system is installed aboard.

The application of degaussing system began during the World War II to avert the naval ships from magnetic bombs and torpedoes. The magnetic field of the ship used to trigger the firing mechanism and makes the mine or torpedo explodes.

Answer: degaussing