This section discusses the equipment and techniques used in plotting.
The dividers (Figure 4.2-13) are used primarily for measuring distances. A secondary use
(when combined with the plotter) is to measure courses.
Figure 4.2-13 Dividers
The plotter (Figure 4.2-14) is a combination protractor and straightedge. It is used to aid in
drawing course lines and measuring direction. The parts of the plotter include the
straightedge itself, the grommet (center hole of the protractor section), and the scales on
the protractor outer edge. The scales run from 0º to 180º on the top of the outer scale, and
from 180º to 360º on the bottom of the outer scale. The number line on the plotter is
reversed (i.e. the numbers increase to the left and decrease to the right). There is also an
inner scale (called the north/south scale) which will be helpful in measuring course lines
that run close to the north-south axis of the chart. Do not use the distance scales on the
straightedge, as they are not accurate. The dividers will be used to measure distances.