The equipment fitted in Queen Elizabeth II was supplied by Aerospace through the International Marine Company. It consists of three units: an aerial, a two-channel receiver and a data processor. The receiver and data processor are housed in a single rack, the print-out machine stands beside the rack on its own pedestal. The aerial reposes on the truck; how-ever, as a result of experiments carried out on board, we are convinced that satisfactory reception of signals is obtained with the aerial sited directly on to the wheelhouse top. The rack and pedestal are located in a corner of the chartroom. Since fitting (Dec. 1968) the receiver has operated continuously, though we must own up to an occasional spot of bother with the processor. Nevertheless the vessel has only on one occasion entered port with the equipment out of use.