Captain Barker's paper was presented at a one-day seminar on The Selection and Display of Navigational Information at Sea, jointly organised by the Royal Institute of Navigation and the Nautical Institute in London on 11 December 1980.

It does not seem so long ago since a shipmaster could not do better than proceed at utmost speed, mindful of sea conditions for heavy weather damage and of fog, for a successful conclusion to a commercial venture. Today the cost of bunkers may exceed the income earned on the freight. Commercial organizations carrying their own cargoes have always had to operate at speeds that relate to freight levels, but owners with their ships on charter, who were never very concerned in conserving bunkers, are now more closely scrutinized on the way they operate their ships, and particular attention is paid to the speed-consumption curve.