Chart Navigation & Plotting · Plotting Tools
Parallel rulers are used on a chart primarily to:
- ATransfer a course or bearing direction to or from the compass rose✓ Correct
- BMeasure distance along a course line
- CPlot a position by latitude only
- DMeasure the height of tide
Explanation
Parallel rulers 'walk' a line across the chart while keeping its direction constant, letting you read a course or bearing off the compass rose or lay one down. Distance is measured separately with dividers against the latitude scale.
Authority: Bowditch, Pub. No. 9 (plotting)
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