This sturdy 12-inch (30.48cm) parallel ruler with brushed aluminum
arms is enscribed with a protractor scale. It is used to plot direction
on a nautical chart from any convenient meridian or compass rose. The
two straight-edged rulers are connected to maintain the same angle. By
walking the rules across the chart and securely holding down the
non-moving ruler, you can effectively plot a course.
Tags: Weems Parallel Rule 12" Aluminum, WAP000140, Navigation