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Module 6 — Position, Course & Speed

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 rose. Read the bearing from the True (outer) ring of the compass rose.

When plotting a bearing of a charted object taken from the boat, plot it from the object on the chart (the reciprocal direction). If you took a bearing of 045°T to a lighthouse, you plot 225°T from the lighthouse.

Key Points

  • Use parallel rulers or plotters to transfer bearings
  • Read from the outer (True) ring of the compass rose
  • Bearings taken FROM the boat are plotted FROM the object on the chart
  • Reciprocal bearing = bearing ± 180°

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