Which tool is used in conjunction with the compass rose when plotting a magnetic direction on a chart?

Which tool is used in conjunction with the compass rose when plotting a magnetic direction on a chart?

• A. Parallel rule
• B. Sextant
• C. Chronometer
• D. Dividers

Answer: (A)

Transferring a magnetic bearing onto a chart requires keeping the angle fixed as you move across the map. The parallel rule is the tool designed for this job: two rulers linked so they stay parallel. You align one edge with the reference direction on the chart (the magnetic bearing shown on the compass rose) and the other edge with the starting point, then slide to draw a line that stays at the same bearing. This lets you plot the course accurately without altering the angle. Other tools serve different tasks: a sextant measures angles to celestial objects for determining position, a chronometer provides precise time for speed and longitude calculations, and dividers help measure or transfer distances on the chart. But for plotting a magnetic direction from the compass rose, the parallel rule is the right choice.

Transferring a magnetic bearing onto a chart requires keeping the angle fixed as you move across the map. The parallel rule is the tool designed for this job: two rulers linked so they stay parallel. You align one edge with the reference direction on the chart (the magnetic bearing shown on the compass rose) and the other edge with the starting point, then slide to draw a line that stays at the same bearing. This lets you plot the course accurately without altering the angle.

Other tools serve different tasks: a sextant measures angles to celestial objects for determining position, a chronometer provides precise time for speed and longitude calculations, and dividers help measure or transfer distances on the chart. But for plotting a magnetic direction from the compass rose, the parallel rule is the right choice.