In the discussion on Blind Estuary Pilotage held by the Institute on 18 June 1948, the writer (see Journal, Vol. 2, No. 1, p. 60) put forward the suggestion that the well-known principle of radar shadowing could be used to provide accurate leading patterns for ships navigating straight channels or harbour entrances. Two possible patterns of this sort are illustrated in Figs. 1 and 2.

The pattern shown in Fig. 1 uses six ‘targets’ and two ‘screens’ and would be suitable for any channel wider than about 200 yards. The channel illustrated is meant to be about 200 yards wide, and the configuration of the pattern—though not the dimensions of the targets and screens—is drawn to the same scale.