Nautical Mile/One Minute of Latitude
We know that we measure in degrees (°), minutes (’) and seconds (ʺ) or decimals of a minute.
One minute of latitude is equal to one nautical mile (1,852 metres or 1.852 kilometres).
TIP: You MUST measure distance from the latitude scale adjacent to the area you are working in on a chart, NEVER from the longitude scale. The Mercator projection used in constructing the chart creates a distorting elongation of the longitude scale.
As well as defining our position in latitude and longitude, our location may be given in relation to a known geographical position, for example: “8 nautical miles southeast of Greenwell Point harbour entrance.”
TIP: When relaying a position, it is good practice – and clearer on the radio – to say each number individually, e.g.
151° 21.12’ E
“One-five-one degrees, two-one decimal one-two minutes east.”
Distance on the earth is expressed in nautical miles, and is the spatial separation of two points.
