A study of many collisions at sea in which the misuse of radar may have been a contributory cause leads to the conclusion that much difficulty might be overcome if a less ambiguous method of displaying radar information were provided. To this end an entirely new type of radar presentation has been embodied in the latest equipment produced by Decca Radar Limited. Type TM 46 displays the radar picture so that the true movements of all vessels, including own ship, can be assessed by inspection of the display. This continuous presentation on the radar screen of the true course and speed of all targets is an entirely new feature in radar equipments. Unlike former systems, where own ship appears continuously at the centre of the display and the movement of other echoes is relative, ‘true-motion’ presentation shows own ship moving across the display at the correct course and speed, and the true movement of other echoes. Stationary objects such as buoys or anchored ships do not move on the PPI and can be readily identified.