Introduction
As most
people have already experienced, technology can fail and should not be relied
upon. The ability to navigate with a map and compass is an essential skill for
anyone hiking or backpacking through the wilderness. In this activity groups
will be using two navigation maps created in the previous week`s lab and a
compass to try to navigate to five points in Universal Transverse Mercator
(UTM) coordinates located in the wooded area surrounding UWEC`s Priory. Both navigation
maps contain two meter contour lines and a grid. One of the maps includes the geographic
coordinate system with a decimal degrees grid and the other map is in a UTM projection
with a 50-meter interval grid.
Study Area
The Priory is a residence hall and children`s
nature academy just over 3 miles south of UWEC`s main campus set on a 120 acre
wooded lot containing a lot of relief. The navigation took place on a warm,
fall day and the sky remained clear for the majority of the activity. Temperatures
during the navigation remained at about 16o Celsius.
Methods
The class met at the Priory and
upon arrival each group received; copies of their previously submitted maps, a course
to navigate, a map compass, and a GPS unit. After a brief map compass (figures 1 and 2) tutorial, each group member marked the five
UTM coordinates on their map and compared points for accuracy. To assist in the
approximation of distance traveled, the two group members who would assume the
pace counter role took a pace count for a 100-yard stretch in the parking lot
(the third group member had an injury which prevented hiking through some of
the terrain). Before embarking on this adventure three different roles were
defined; the pace counter, azimuth control, and pace count recorder. The azimuth
control would use the compass to determine the correct direction of travel and
choose a landmark for the pace counter to travel to, then the pace counter
travel to the specified landmark while counting the paces it took to reach the
landmark and yell out the number of paces taken for the recorder to document
and keep a running total. The 100 meter pace count could be used to produce a
rough estimate of the number of steps needed to reach the points based on the
map`s scale and measured distance from point to point. It was now time to choose a starting point and
determine azimuth from the starting point to the first point of the course. From
a point easily locatable on the map; the map itself was laid on a flat surface,
the compass was set on it and orientated true north by matching up the red
arrow and the red outline below it, the map was then rotated properly so that
is was also orientated true north. The edge of compass was then aligned with
the anchor arrow at the starting point and the direction arrow aimed at the
first destination, then the compass housing had to be rotated until the
orienting lines were lined up with the lines of longitude on the map, thus
facing north. The directional arrow now marked the bearing needed to travel to
reach the first point. After the pace counter reached
each landmark, the azimuth control would walk to that location and reassess the
bearing by holding the compass so that it was facing due north. A new landmark
could then be determined based on where the directional arrow was now pointing.
The recorder would keep a running total of steps taken, adding a roughly
estimated distance to account for relief as it was traversed, and alerting
group members when the point, marked by a pink ribbon (figure 3), should be nearby. The group member not responsible for pace counting
would then conduct a brief reconnaissance to see if it could be located before
sending the pace counter further. For
each point the approximate bearing was recalculated and the process repeated. However,
after successfully locating the first point, the second point was elusive and a
pink ribbon was found on the ground some distance away from where it was
thought the point should be. In an attempt to move on, the bearing for point
three was determined based on the assumed approximate location of point two.
After searching a broad area around the assumed location of point three without
success, the GPS was consulted to approximate bearing and distance between
actual location and marked location for point three. It was again assumed that
another ribbon had been removed from the tree and point four was approximated
from the current location according to the GPS. After yet again failing to find
an actual marked tree, class was almost over and a hasty attempt to locate
point five was made based on current location according to the GPS. These
efforts were to no avail and it was time to use the recently practiced map and
compass navigation skills to return to the Priory where the lone Dr. Hupy
awaited our arrival.
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| Figure 1. Compass similar to the one used |
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| Figure 2. Compass with parts labeled |
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| Figure 3. A point marked by a pink ribbon |
Results/Discussion
The GPS track log mapped out
with along with the plotted points reveal how accurately the course was
navigated. Point one is the point furthest south, point two being the next one
closest to that, and points three, four, and five are in a counter-clockwise
order (figure 4). Oddly enough, it appears point
one was missed and perhaps the point located was part of a different course. It
also seems point two would have been successfully located and it was correctly
assumed to have been removed. Navigation from point two to point three appears
to be where things went wrong. The general direction of navigation is accurate,
but the distances traveled were not at all sufficient to reach points three or
four. There are two likely explanations for this error; first the approximation
for point two`s location may have been off and the approximated addition of
steps necessary based on relief was most likely off. Point five appears to have
been in relatively close proximity; however hasty searching that had extended
beyond the class’s meeting time may have caused the group to miss the last and
final point.As
for the navigation as a whole, another source of error could have been the
overlooking of declination. A post lab calculation for the day the activity
took place found it to be 1.14°
W ± 0.39° changing by 0.06° W per year. This seems
to be quite negligible and should not have altered the results too greatly, as
omission of declination should still have resulted in close vicinity to the
target.
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| Figure 4. The course points mapped with the navigation track log |
Conclusion
Of the two maps created, the UTM
map was most helpful. The feature of greatest assistance was the grid; the grid
lines were left subtly visible on the map making it easier to assess location. The
points were plotted on this map and the 50-meter intervals helped in assessing distance.
After the GPS track log had been changed to this projection it also gave UTM
coordinates, so the UTM map was also used in orienteering when a point seemed
to elude the pace count method. After point one was located all other points
were within areas of great relief and the contour lines were somewhat helpful
when a point was thought to be nearby. They were used to decide if said point
should be at the base, summit, or side of a ravine. If given an opportunity to
repeat the activity, subtle three meter contour lines with a slightly more
visible 25 meter grid might be of more use. Previous experience is also a very
helpful asset in this sort of activity and the knowledge to take the concept of
distance change in relation to relief into account will be taken away from this
lab. This lab was a fun, educational challenge that taught a valuable life skill
to someone who can frequently be found in hiking in the wilderness.
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