Navigation and Seamanship

1.4.5.8. Natural scale

Natural scale is the relationship between the actual length of something on the earth and the length by which that thing is shown on the chart. It does not matter what size the unit is or in what system it is measured for example, a scale of 1/80,000 or 1 : 80,000 means that one unit (inch, foot, meter, mile etc.) on a chart represent 80,000 such unit on the earth.