Even as recently as 1954, although informed opinion ashore was otherwise, at sea, and here one can only broadly generalize, the principles of plotting were neither universally accepted nor practised, and it may be that this was due largely to the fact that there still remained disagreement as to the practicability of plotting. Indeed, even now, there must be a limit on the number of targets that can conveniently be manually plotted.

The Safety of Life at Sea Convention, 1960 amended the Collision Regulations to take cognizance of radar, and to give guidance on the use of radar in fog. The Admiralty Court has indicated that if a vessel is fitted with radar she is obliged to use it and, even more important, that there is an obligation upon the observer to use the radar properly. The phrase ‘using the radar properly’ has in Case Law been judged to necessitate some form of plotting, and it is of passing interest to note that the vast majority of collisions involving vessels fitted with radar can be attributed to immoderate speed, or a failure to appreciate the information provided by the PPI.