The use of leading marks in pilotage is a procedure familiar to all seamen, and wherever leads are sufficiently easy to recognize on the screen the technique can be extended to use with radar, due note of the lowered degree of precision being taken. In this account of a passage through the exit to Singapore Strait, Captain Robb, a shipmaster of the Blue Funnel Line, and author of several works on radar use at sea, describes a less well known method in which off-set marks are used for conning the ship by radar. A similar technique was suggested in the Journal (9, 445) by Mackay.