Distance on a nautical chart should be measured using which scale?

Distance on a nautical chart should be measured using which scale?

• A. Parallel Latitude Scale
• B. Meridian Scale
• C. Longitude Scale
• D. Vertical Scale

Answer: (A)

Distance on a nautical chart is measured using the parallel latitude scale. This scale is calibrated to show nautical miles for distances measured across the chart in the east–west direction (between longitudes) at the chart’s latitude. Since the actual ground distance represented by a degree of longitude changes with latitude, the parallel (latitude) scale provides the correct conversion to nautical miles for those horizontal measurements. The vertical (meridian) scale would be used for north–south movements along a meridian, while the vertical scale isn’t used for general distance between two points.

Distance on a nautical chart is measured using the parallel latitude scale. This scale is calibrated to show nautical miles for distances measured across the chart in the east–west direction (between longitudes) at the chart’s latitude. Since the actual ground distance represented by a degree of longitude changes with latitude, the parallel (latitude) scale provides the correct conversion to nautical miles for those horizontal measurements. The vertical (meridian) scale would be used for north–south movements along a meridian, while the vertical scale isn’t used for general distance between two points.