Pages

Sunday, March 10, 2013

Field Activity #6: Navigation with a Map and Compass

Introduction

This week’s field activity was a continuation from last week’s activity of creating a navigational map (images 1 and 2). The purpose of this week’s activity was to learn how to navigate using a map and compass. To do this, our professor provided us a series of points to plot on our map (image 3).

Image 1: Navigational map of landscape terrain created in previous week’s lab
 
Image 2: Reference side of the navigation map created in previous week’s lab

Image 3: Sheet provided to us by our professor with the points coordinate location

Then we had to establish a distance and azimuth from point to point in the direction we would be navigating. We established our azimuth using a compass. Azimuth is the angular distance along the horizon to the location of the object. It is measured from north towards the east along the horizon (image 4).
Image 4: How azimuth is determined
 
 
As mentioned in Field Activity #4: Distance and Azimuth Survey, before one can use a compass they need to check the magnetic declination of the place they are using it at. Magnetic declination is the angle between compass north and true north. Compass north is the direction the north end of a compass needle points, while true north is the direction along the earth's surface towards the geographic North Pole. Magnetic declination varies both from place to place and with time. In Field Activity #4 we established that the magnetic declination of Eau Claire, WI was 0ᵒ 59’ W. Since 0ᵒ is such a small declination no adjustments to the compass is necessary.

To establish our distance on the map we used the 50x50 meter grid. In the field we used the 100 meter pace count we establish the previous week.
After all of this was established we headed outside to one of the three established courses to locate our waypoints. Our team traversed course 3.

Methods
To begin this activity we plotted the points (image 5) provided to us by our professor, which correlated with the course our team would be traversing. We plotted our points using the UTM X and Y coordinates (image 6). We used these points because our map’s coordinate grid was established in a UTM projection.  

Image 5: Plotting our points
 
Image 6: Sheet provided for us by our professor with UTM X and Y locations of our waypoints
 
 
After plotting our points individually our team went through and compared out points to one another to make sure we had them plotted correctly.

Next, we had to establish a distance and azimuth from one point to another. Since there was a total of 6 teams and only 3 courses, 2 teams had to traverse the same course at the same time. So, one team worked from point 1 to point 6, and the other team worked backward from point 1 back to point 2. Our team worked backwards, so we went from point 1 to 6, then 5, 4, 3, 2 then back to 1 to finish. We established our azimuth using a compass (image 7).
Image 7: Compass used to establish azimuth
 


1. First, I drew a line from point to point in the order we were going to be traveling.

2. Next, I laid my compass on my map with the center of the turnable housing unit (screw that holds needle in place) over the point I was starting at. For example, if I was working from point 1 to point 6, I laid it over point 1.

3. Then, I made sure north, on the turnable housing unit, was in the direction of north on my map (image 8).

Image 8: Turnable housing unit’s north in same direction as north on map
 
4. Next, I made sure the heading arrow was lined up with the line I drew from point 1 to point 6

5. Then, I read the number that correlated with the heading arrow; which is the azimuth; and wrote it on my map next to the line connecting the 2 points.

6. Lastly, all the team members compared their azimuth to each other’s to make sure we were all within a small range from one another (about 7◦ or less).
Next, we had to establish our distance from one point to the other in the order we were traversing. To do this we used the back side of the sheet of paper that had our point locations on it, and the ruler on the compass.

1. First, we lined the sheet of paper next to the grid on the map and made tick marks on it at every 50 meter increment.

2. Then, we labeled the tick marks with the corresponding distance from the map’s grid.

3. Next, we laid the paper on the map with a distance of 0 at the point we starting at to the point we were traversing to (image 9). For example, if we were measuring distance from point 1 to point 6 we place 0 at point 1 and measure the distance to point 6.

Image 9: Measuring distance from point we were traversing from to the point we were traversing to using a piece of paper with 50 meter increments measured  on it
 
4. If the point laid in a position where a 50 meter increment reading wasn’t accurate enough we used the ruler on the compass to get a more accurate reading.

5. Again, we compared our distances to one another to make sure we were all in an appropriate measurement from each other.
Once all distances and azimuths were established we created a chart that corresponded the distance and azimuth to appropriate point (image 10).

Image 10: Chart containing distance and azimuth with corresponding point
 
The last thing we did before going outside was poke a hole through the map from the navigation side to the reference side at each point (Image 11). We did this in so that if we needed to use the reference side of the map in the field we would know exactly where it was, without having to flip the map over several times. This would allow us to be more accurate and save time in the field if the reference side of the map was needed.

Image 11: Poking holes through the map from the navigation side to the reference side at each point
 
Finally, we were ready to go outside and execute the physical part of the navigation activity. For this we only took one of the 3 maps. This was because it is easier to have less to worry about and carry when hiking in the field.

To start, we shown where to start for the particular course we were navigating. For course 3 a tree was the starting point (image 12), also known as point 1.
Image 12: Starting point for course 1, also point 1 for that course
 
 

To get from point 1 to point 6 we referred to the distance and azimuth chart, we created for our course, and read the distance and azimuth for point 1 to point 6. Using the compass in the field for azimuth differed slightly from how we used it inside to establish azimuth on our maps.
1. First, we made sure the red N for north on the compass’s turnable housing unit was lined up the heading north arrow (image 13)

Image 13: North indicator on the turnable housing unit lined up the heading north arrow
 
2. Then, we held the compass with both hands on the beveled end of the base plate with the heading north arrow pointed directly perpendicular from our bodies. While doing this it is important to hold is slightly away from your body and also not close to any metal (i.e. rings on your fingers, button on your coat, etc.). This is because metal off-sets the compass needle slightly.

3. Next, we turned our entire bodies with the compass until we got the needle lined up directly with the red arrow inside the turnable housing unit (image 14).
Image 14: Needle lined up directly with the red arrow inside the turnable housing unit
 
 
4. Then, we found to the azimuth number on the turnable housing unit that corresponded with the azimuth on our chart and found a land marker in that vicinity to walk towards.

After the direction (azimuth) we needed to go was established we were ready to walk. This is where the pace count from last week came into play. Knowing how many paces we took in 100 meters made it easy to pace out since the distance we measured on our maps, using the grid, was in 50 meter increments. Being accurate with our pace counts was very important because we had 3 courses that were all overlapping one another. It was important to know how far you were so you didn’t see a point marker that intersected the marker you were going from to the marker you were going to and automatically assume it was the point you were looking for. If this happened, the next azimuth would be inaccurate with the direction you needed to go to get to your next point; and you would basically be lost for the rest of the navigation.
1. To be accurate with our pace counts we had one person walk first and stop when they got to 100 meters (image 15 and 16).

Image 15: First person walking 100 meters
 
Image 16: First person at their 100 meter pace count
 
 

2. Next, another group member walked and see how far their 100 meter pace compared to the first person.
3. If the two were accurate with one another one of the two would continue to walk.

4. The third person stayed back at the point we started from to make sure the two pacers stayed in line with the direction they were supposed to be heading.

5. After one of the walkers continued to walk a second increment the last person (the direction monitor) would walk to the pacer who stayed at the 100 meter mark.

6. We continued this trend until the marker was spotted (image 17 and 18)
Image 17: Looking for the marker upon approach
 
 

Image 18: Markers that marked the point we were navigating to
 
7. Finally, we punched a hole in our navigation sheet (image 19), with the provided hole puncher at the marker, to show that we had found our point.

Image 19: Holes punched in navigation sheet to show we had found our point
 
We continued this method until all 6 points were found.

Discussion
Overall, we found that our distances and azimuths were very accurate. We found that we barely needed to use our map at all. The one time we did use our map we found it very helpful because we thought we were a little off on our azimuth. This happened because it is hard to walk in a straight line when walking up and down steep ridges with trees and brush in your way. When you have to walk around things such as these it’s difficult to get back on the right path, while still maintaining accurate pace counts. Our map designed for the situation proved very appropriate for depicting the terrain of the landscape. We were easily able to locate, from both sets of contour lines, the top of the ridge we were standing on. From this we were able to see we needed to head more to the left or more to the right while walking down from the ridge to get to the point we were navigating to. We also found that we never needed to refer to the reference side of the map, which had the aerial photo on it, to try to figure out where we were.

From this we learned that generally, we were all pretty accurate with one another’s pace counts. Again, this was much easier on flat ground where trees and brush were minimal. One thing I learned is that you need to be consciences of your pace lengths when walking through snow and brush. Typically, I find that I’m a fast walker and walk take longer strides than most people my height. However, in these snowy, brushy, and hilly conditions I found that my strides were much smaller. I almost needed to count 2 paces as 1 at some points.
Conclusion

I can definitely say that I learned a lot from this activity. I am very happy that I had the opportunity to learn these skills. I definitely think that having us create our own maps made us much more aware of the importance of appropriate map styles for certain activities. I don’t think there is anything I would change about my map. The thing I found most useful about the map was the 2 foot and 5 meter contour lines. The 2 foot contour lines depicted the terrain very well. The 5 meter contour lines came in very handy because those were labeled with their elevation, so we were able to compare them to the 2 foot contours to know if the 2 foot contours were depicting a valley or ridge feature of the landscape.  Having the 2 foot contours labeled with their elevation would’ve made the map way too busy and confusing. From this, I also learned the importance of having accurate and detailed data for a map. I don’t think the 5 meter contours alone would’ve been as good at depicting the landscape terrain.
Last but not least, we can’t end this discussion without talking about how important it is to come prepared for the weather. All of the other outdoor field activities we’ve done this semester haven’t involved too much movement; more just standing around. So I dressed really, really warm knowing we would be knee deep in snow for parts of the day. What I found is that I dressed way to warm for the type of terrain we were traversing. I got hot immediately and needed to start unlayering. Although I was much more comfortable after taking off one my sweatshirts, I found it very annoying having to carry it the whole time (image 20). It was also difficult because it kept getting caught on brush and twigs.

Image 20: Carrying a sweatshirt through the entire course was very annoying and difficult
 

No comments:

Post a Comment