The proposal by A. J. Wright (this Journal, vol. 34, no. 1, p. 142) that banded contour charts should be introduced, appears attractive at first sight. It appears to provide immediately recognizable indication of safe areas for the navigation of those ships whose draught is within certain limits. However, I feel that the system as proposed suffers from some major weaknesses

Allowance for height of tide. Tidal ranges of several metres are by no means uncommon. Failure to make proper allowance for this could result in a wrong assessment by the user of where navigationally safe water lies. Such tidal ranges frequently occur in areas of high-density traffic. Here, the pressures on the mariner are such that the temptation to ‘eye-ball the navigation’ is greatest – yet it is in such areas that positional accuracy based on sound chartwork procedures is vital.