To convert from seconds to tenths of
minutes, divide the number of seconds by
60. For example, 30 seconds is equivalent
to 30/60 minutes, or 0.5 minute. (Example:
L 42° 34´ 30´´ N, Lo 072° 36´ 48´´ W is the
same location as the example in the previous
paragraph.)
Section 17: Introduction to Navigation 197
If you are using charts in a region with
mixed scales, you must select one for your
GPS. You will need to convert from one
to the other in order to enter waypoints.
Generally, the use of degrees, minutes, and
tenths of minutes is preferred since you can
use the latitude scale as a convenient distance
scale.
Skill—Measuring the Latitude
and Longitude of a Point on the
Chart
This skill is required in order to enter waypoint
locations into your GPS for navigation.
Follow along on the figures as you
read the step-by-step instructions below.
This will be followed by an exercise. For the
exercise, you will need just your dividers
and the blank chart sample in back of this
manual.
You can follow along on the plotting
exercise at the back of the book while you
execute the following steps:
1. Identify the point you want to measure.
In this exercise, you will start with measuring
latitude (Figure 17-15 a,b).
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56
57
58
59
Figure 17-14. Latitude and longitude scales
Figure 17-15 a, b. Measuring latitude