In this paper, by the Director of the Radio Advisory Service, a comprehensive survey i s made of all the main trends of development in commercial marine radar since it first went to sea in 1946. The opinions of a representative group of seamen on the value they get from radar is analysed, and finally some views of manufacturers and seamen on what the future may hold are examined. The paper was presented at the annual meeting of the Ausschuss fur Funkortung held in Kiel on 10, 11, 12 September 1960, and is reproduced with the kind permission of that body.The last fifteen years represent almost exactly the whole life of commercial radar in merchant ships; in the United Kingdom the first commercial types were beginning to go to sea towards the end of 1946. The period has been an intensely interesting one from almost every aspect of the subject and the writer is fortunate in having been associated with merchant ships, and their owners, for thirteen of these fifteen years and with the subject of radar at sea since 1936.