Magnetic survey instrument and composite type magnetic survey instrument having a plurality of it

摘要

PURPOSE:To survey a subaqueous cable easily with high accuracy through a simple constitution by securing the horizontal holding part to the side part in the longitudinal direction of a sensor container. CONSTITUTION:The sensor container 2 for a magnetic survey unit 1a is made of a nonmagnetic material into a long tube. A magnetic sensor is loaded therein and a horizontal holding part 6 made of a nonmagnetic material, e.g. a wood plate or a synthetic resin plate, into a hollow disc is secured 7 to the side part in the longitudinal direction of the container 2. The survey unit 1a is sustained at a predetermined depth from the sea bottom by means of a weight 11 suspended from a rope 13 when a survey vessel is towed through the tow rope of a hauling member 8. Since the survey unit 1a is imparted with buoyancy by the holding part 6 at the time of towing and the weight 11 is pulled, the survey unit 1a is towed constantly in parallel with the sea bottom and the advancing direction while keeping a constant height from the sea bottom. Consequently, a pipe line embedded in the sea bottom can be magnetically surveyed easily with high accuracy.