The classic application of marine magnetics is a magnetometer being towed close to the water surface by a data and power cable behind the ship. The distance to the ship must be several hundred meters in order to avoid the ship's own magnetic field. In the modern design, we combine several magnetometer probes in a line in order to measure the gradient of the earth's magnetic field and its components in three spatial directions (vector magnetometer).
At BGR, we use a towed gradient magnetometer based on a refined principle of proton magnetometers (Overhauser magnetometer) to measure the Earth's magnetic field at the water surface, which can suppress the disturbing temporal variations of the Earth's magnetic field. In addition, BGR uses towed magnetometer and those installed on the research vessel to measure vector components of the magnetic field.
As it is not always possible to use magnetometers towed behind the ship, magnetometer probes are also installed directly on the ship, usually high up in the mast. Although the measured data are considerably influenced by the ship's own magnetic field, this effect can be eliminated by post-processing.
BGR also owns various magnetometer types for use at great water depths. These can be mounted on our deep sea platforms (e.g. Homeside, ULLA, Golden Eye, SPOCK) and are primarily used for local-scale investigations of mineral resource deposits on the seabed.
For use in the deep sea at water depths of about 2000 m to 4000 m, the magnetometer sensors are installed in pressure tubes and modularly mounted on various devices that operate close to the seabed.
