High-resolution magnetic mapping as a component of multi-parameter surveys

The 1992 survey of CSS Matthew represents a new approach to ocean mapping in terms of precision and resolution of survey parameters. Advances in navigation using satellites have been refined with the Differential Global Positioning System (DGPS) so that the position of the ship can be fixed continuously (at intervals of 1 to 2 s) with an accuracy of 5 m. The multibeam sounding method requires a spacing of survey lines no greater than twice the water depth for 100% coverage of the seafloor. To achieve full resolution, geophysical parameters (magnetics and gravity) are measured at 20 m along track (i.e., every 4 s). A survey over the shipwreck of the tanker "British Freedom" off Chebucto Head illustrates recent advances in our survey methodology.