DAVIS Charting Kit - Manual (Page 3)

#064 COURSE PLOTTER
TO MEASURE COURSE ANGLE:
1) Place either long edge or any of the parallel lines of the plotter along the course
line.
2) Slide the plotter along the course line until the center point is at a meridian of lon-
gitude or a parallel of latitude.
3) If the center point is at a meridian, read the bearing at the meridian using the
large outer scale. Use the outer numbers of this scale if you are traveling in an
easterly direction and the inner numbers if you are traveling in a westerly direction.
4) If the center point is at a parallel, read the bearing at the parallel using the
small inner or auxiliary scale. Use the outer numbers of this scale if you are travel-
ing in a southerly direction, and the inner numbers if you are traveling in a norther-
ly direction.
5) To find magnetic course, add or subtract the local variation given for your area in
the center of the compass rose on your chart.
TO DRAW A COURSE OR BEARING FROM A POINT:
1) Place the center of the plotter on a meridian or a parallel. Rotate the plotter until
the desired bearing is read at the meridian or parallel. Use the large outer scale if
you are reading at a meridian and the small inner or auxiliary scale if you are
reading at a parallel. (Note: When drawing magnetic course, be sure to adjust your
bearing for variation as in step #5 above).
2) Keeping the center point and the desired bearing on the meridian or parallel, slide
the plotter along the meridian or parallel until the outer edge of the plotter touches
the point.
3) Draw the course line along the straight edge of the plotter.
OTHER USES OF COURSE PLOTTER:
1) Extend a line by sliding plotter against a triangle or the two tips of a divider.
2) Advance a line of position by using parallel lines on plotter.
3) Measure distance using chart scale on either long edge of plotter. Be sure to use
the scale (1:80000 or 1:40000) indicated on your chart.