Some 7 years ago the North Sea Hydrographic Commission took up the question of deep draught routes in the North Sea and a basic pattern was selected and examined against existing hydrographic materials by the members of this Commission. In 1966 Shell International Marine produced a publication entitled The Channel and North Sea Routeing Folder. These more detailed routes together with the basic ones proposed by the Hydrographic Commission (although they are in no way official or necessarily accepted) form the basis of our present thinking on routes and planning of surveys in this area.

It was only a few years ago that a draught of 50 ft. was exceptional and it was generally considered that draughts were unlikely ever to exceed 60 ft. In fact draughts have increased rapidly ever since and for this reason, last year, we extended the limit to which we show soundings in fathoms and feet from 11 to 15 fin. in areas where deep-draught vessels could be expected to operate.