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Module 6 of 17

Position, Course & Speed

True bearings, courses, latitude, longitude, and the knot.

True bearings and coursesStandard navigational termsLatitude and longitudeThe knot

Lesson summaries

Use this module hub to choose the right lesson, then open the dedicated lesson page for the complete explanation, worked examples, FAQs, and practice questions.

Latitude and Longitude

Position on the Earth's surface is defined using latitude and longitude. Latitude measures north or south of the Equator (0° to 90°N or S). Longitude measures east or west of the Prime Me...

  • Latitude = N/S of Equator (0°–90°)
  • Longitude = E/W of Greenwich (0°–180°)
Read the full latitude and longitude lesson

True Bearings and Courses

A true bearing is measured clockwise from True North (0°/360°) through East (090°), South (180°), and West (270°). All chart work is done in true bearings initially — compass corrections...

  • True bearings: measured clockwise from True North
  • Always written as three figures (e.g., 005°, 090°, 180°)
Read the full true bearings and courses lesson

Speed, Distance, and Time

Speed at sea is measured in knots — one knot equals one nautical mile per hour. Distance is measured in nautical miles (M or nm). One nautical mile = 1,852 metres = 1 minute of latitude.

  • 1 knot = 1 nautical mile per hour
  • 1 nautical mile = 1,852 metres = 1 minute of latitude
Read the full speed, distance, and time lesson

Measuring Bearings on the Chart

To measure a bearing on the chart, use a parallel ruler (or Breton plotter). Align the ruler along the line whose bearing you want to measure, then 'walk' it across to the nearest compass...

  • Use parallel rulers or plotters to transfer bearings
  • Read from the outer (True) ring of the compass rose
Read the full measuring bearings on the chart lesson

Measuring Distance on the Chart

Distance on a nautical chart is measured with dividers and the latitude scale at the side of the chart. One minute of latitude equals one nautical mile, so the latitude scale is the only...

  • ALWAYS use the LATITUDE scale (side of chart) for distance
  • 1 minute of latitude = 1 nautical mile
Read the full measuring distance on the chart lesson

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