More than 1200 American radar equipments have been fitted to ships and this paper gave same American views on its operation; the views put forward were not necessarily different from those held in this country but certain experiences of inland navigation and blind pilotage which would be new to British operators were described. It was stated that when commercial production of marine radar started in the U.S., opinion was divided on the relative merits of 3 cm. and 10 cm. radar, some manufacturers concentrating on one and some on the other. Although 10 cm. equipment is still manufactured, all manufacturers now have a 3 cm. radar in production.

Certain advantages of radar assisted navigation were mentioned and these included the ability to determine another vessel's course and speed by plotting and the considerable saving in fuel and time that could be achieved by the accurate knowledge of the ship's position in coastal waters no matter what the weather.

Anomalous propagation in the Great Lakes region was described as being so common that shipmasters often regard the increased range of radar in the area as being the normal range of the set.

The use of radar by tugs on the Mississippi and its tributary the Ohio was described. Here up to fifteen barges of 100 ft. are ‘shoved’ by the tugs into narrow locks in weather which sometimes conceals half the tow. The small bump in the trace, representing the lock, is recognized by the pilots. One of the outstanding problems of this form of radar navigation was stated to be that the bridges (of which there are 1700 over the Mississippi) were such good reflectors that discrimination between them was not possible at a mile, at which distance the tow gets into position to pass between the piers.