Staying on Course
Sixth article in a seven-part seriesBackcountry activities seldom involve simply going from point A to point B. Planning a trip, especially in unfamiliar country, requires selecting several locations along a route and noting essential information for each:
- Point location (waypoint)
- Compass bearing to the next point
- Distance between points
Here's a short trip planning exercise to show how effectively map, compass, and GPS work together.
There are lots of trails and access roads on Peach Mountain (as shown in this enlarged section of the 7.5-minute topographic map). I've laid out a short route using part of the road and several sections of trail. I've noted each one of the intersections along the way and given them a number. To start my route-planning exercise I'll measure each of the points using the UTM system.
The coordinates for the seven points are:
- E (02) 58.200 N (46) 97.100
- E (02) 58.450 N (46) 97.800
- E (02) 58.500 N (46) 97.550
- E (02) 58.850 N (46) 97.600
- E (02) 59.100 N( 46) 97.650
- E (02) 59.000 N (46) 98.000
- E (02) 58.600 N (46) 97.850
I enter the coordinates into my GPS, saving each one as a waypoint. Usually I'll give waypoints distinctive names but, for the sake of this exercise, numbering each one is enough.
I open a new route page in my GPS and assemble the waypoints in order, finishing with waypoints #2 and #1 to complete the route and bring me back to the starting point. Notice how the GPS has calculated the compass bearing and distance from each waypoint to the next. Just to be sure of my measurements, I use a plotter on the map to check some of the compass bearings and dividers to verify distances. Happily, everything checked this time, though that's not always the case. This is the best way to find errors in measurements or typos you made when entering data into the GPS.
If you want to use it, your GPS probably has an active route function that will provide GOTO steering all the way around the route and a track-back utility that will reverse a route if, for some reason, you want to bail out and retrace your steps back to where you started.
A couple of important things to remember here: All compass bearings and distances are "as the crow flies," meaning the shortest distance between two points. Actual compass directions will vary around the route as will distance traveled. A short distance on a map or as calculated in a GPS will get a lot longer when there are significant slopes in the terrain as indicated by the tight contour lines around Peach Mountain. This is good to remember if you want to finish a route at a specific timesuch as before dark.
Details mentioned in this article were accurate at the time of publication