13.—Sea-floor Sediment Mapping by Sonar Methods

Synopsis A system is described which produces true-to-scale sonar maps of the sediment patterns on the seabed of the Continental Shelf waters. Correction is made for the speed of the ship over ground, and the 'drift angle' of the sonar beam during passage from one station to another. Work at sea has been extended to water depths of 250 metres, and the technique has been widely used for cable route surveys.