This paper is concerned with a limited part of the marine radar field, namely the equipments intended primarily for the larger ships. In these sets the greatest refinement and versatility is aimed at, to cover the wide variety of circumstances met with by the ocean fliers, the great tankers and the deep-sea tramps seeking port in any corner of the world. The paper is a factual record of radar characteristics as we enter the sixties and the fifteenth year of commercial radar; it seeks to make no invidious comparisons, but it is intended mainly to provide food for thought.

Marine radar has reached a very interesting stage in its progress. From 1947 to 1952 there was a gradual development in the United Kingdom towards a common, rather strict, specification. In the United States there was a similar trend towards a somewhat different standard. Between 1953 and 1959 the American tendency was to move towards the high definition favoured by Britain while British manufacturers began to offer the large diameter displays, 15 or 16 in., which were always popular in the States. Other trends on the whole have been similar, that is towards high definition, operational refinement, general reliability and better control of rain and sea clutter.