Many marine service companies are acquiring boat-towed metal detectors and magnetometers to assist in salvage operations and geophysical surveys. These devices can locate a variety of targets including sunken vessels, ship anchors and propellers, pipelines, cables and metal debris which must be removed from an area before dredging. The two primary pieces of equipment used in these operations are a magnetometer and the pulse induction (PI) metal detector. Magnetometers are super sensitive instruments that can detect iron and steel objects at hundreds of feet away.