In discussing certain aspects of the manœuvring of large tankers it is necessary to consider the navigational circumstances, and especially the hydrographic and meteorological conditions that obtain in the Europoort-area which can be divided into three zones (Fig. 1):

(i) the approach route through the English Channel and the southern part of the North Sea to the outer approach channel;

(ii) the approach channels—the outer channel (bearing 82° 30′) and inner channel (bearing 112°)—to the harbour mouth near the Hook of Holland;

(iii) from the harbour moles through the temporary mouth to the Europoort basin, ending in the berthing manœuvres alongside the jetty.