Anyone who has read articles by the present writer about automatic radar plotters but has not handled at sea one of those systems in which the vector lengths are time-correlated and have a fine (minute-by-minute) adjustment, might think that they tend to exaggerate its importance as an aid to realistic and rapid appraisal. I hope that the pictorial presentation which follows may serve to reverse such opinions even though, with still pictures, it is difficult to create the sense of a continuous and rapid series of brief manual movements and mental assessments.

Far from needing elimination, as suggested by Riggs (Journal, 28, 143), the rapidly extensible vectors lend apparent acceleration to the radar picture, which always changes so slowly on the PPI, and thus convey with verisimilitude a sense of the predicted movement of the entire complement of echoes in their proper mutual relationship. Further, in situations demanding particular care or perhaps a change of course or speed, they can be used to give a rapid forecast of the probable duration of the emergency.