Navigation With Map and Compass

Introduction:

The purpose of this lab was to use simple distance / azimuth measurements to navigate UW-Eau Claire's land at the Priory. This involves simply using a compass, pace measurements, and the navigation maps we created earlier in the semester. For more information on the navigation map's creation refer to this post.

Before going out into the field, it was vital that to do some background research on the basic principles of orienteering. The professor and a classmate compiled some resources to facilitate this. They also printed the navigation maps referenced above for each group, and provided us with compasses.

The object of this lab was to navigate to a number of different points given to us by the instructor using just our distance / azimuth tools and pace counts in groups of three. For more information on distance / azimuth surveying, refer to this post.

This is a compass similar to the one used in this exercise. The general idea is that first, the compass is lined up from the starting point, to the desired point. The red circle can be spun in order to line up with North on the navigation map, then the whole compass is spun so that the actual North arrow is within the red outline pointing north. Finally, the arrow at the top of the image is followed as the direction of travel.

Methods: 

Upon arriving at the priory, each group convened to plot coordinates given to us by the instructor. There were 5 points total given to us in a UTM coordinate system. The first step was to plot these on each map. Next, our compasses were used to calculate the azimuths that would be needed to follow to go from one point to the next. The instructor and a classmate also gave the class important advice on proper methodology to follow to maintain a valid course.

Groups planning for the navigation exercise

To find the proper bearing, the compass must be laid on the map on a flat surface. It must then be lined up from the starting point (the location in the Priory parking lot) to the first point marked by the instructor. Then, North must be lined up with North on the map. This is done by spinning the red circle (see above image for details). Next, the whole compass can be picked up and spun so that the actual North arrow falls exactly within the outline. This is commonly called "putting red in the shed." Being sure to maintain red in the shed, the arrow at the other end of the compass is followed. This is the direction of travel.

Another important step before heading out, is calculating the approximate number of paces to expect before reaching the desired point. The navigation map that was used had a pace count for a group member, so the scale bar had to be used to calculate approximate number of his paces between each point. Note: we calculated this along with the bearings for each point before heading out into the field. This ensured that we had a flat space to calculate them on, and was ultimately less trouble than attempting to figure it out in the field.

A snapshot of the field navigation map that was used. Note the measurements taken on the map. This was done before surveying. 

Groups of three are ideal for this type of surveying. One person is in control of the compass, and directs another group member to a landmark that falls within the proper bearing, then the pace counter can walk to that person. Only after this is done can the compass-holder follow. This ensures that if there is some error, that reference point can always be returned to, and measurements can be retaken from that spot.

There were a total of five points to find using this methodology, and each group had a different order assigned. 

Results:

The first point that this group was assigned to. This particular point was the hardest one to find, as it was down in a ravine 10 to 20ft, and because we hadn't solidified our methodology yet. See the discussion section for more information on this.

The second point assigned to this group.

The third point

The fourth point assigned

The fifth and final point

Discussion:

There was some difficulty in finding the first point. Our azimuth measurement must have been a little bit off, because we ended up considerably East of the desired point. This was exacerbated by the fact that this was the farthest distance between points in the entire study. There came a point, that having little success with our three person survey method (described above), that we all grouped together looking around the nearby area for the point. This is a natural human response to being lost, but it only makes the problem worse. This means that we lost our points of reference, and no longer had any way of knowing where our bearing was. Luckily, we stumbled upon the point, and were able to continue the activity, being sure to be more careful in following our azimuth. The rest of the points were found relatively easily. To find the third point assigned, (point 1) it was advised that we first make a bee line towards the parking area in which we started, then following an azimuth a short distance to the point. This allowed for easy measurements, and less difficulty traversing difficult (sometimes impassable terrain). 

Conclusion:

Knowing how to navigate using simple tools is essential for field work, because as is well known: technology can and will fail. It is very plausible that a GPS wouldn't have reception under the heavy tree-cover and in the ravines of the Priory, so using a compass and navigation map was very possibly the only way to navigate the land there.