Since government and industry have officially accepted the introduction of the International System (S.I.) Units for all forms of measurement it is relevant to examine the implications of this for marine navigation.

The present situation. Marine navigation is no different from many other fields in that a proliferation of units is used to measure the same dimension and, moreover, these units have no systematic relationship to each other. In this respect length is the worst offender: we measure heights in feet, depths of water in fathoms, distances in cables or nautical miles and moreover these nautical miles may be British standard, International standard or those precisely determined by latitude.