There are many obstacles that can prevent you from following the direct route to your destination – lakes, rivers, bluffs, steep-sided gullies and patches of bush lawyer or ongaonga. Many are small enough not to severely affect your line of travel, but others require a major change of direction. If you are using the magnetic-bearing method, you will make direction changes using the orientating arrow. There are a number of ways you can detour around obstacles. The following are two of the most common methods.
Back-bearing method
Figure 102 Navigating around an obstacle using the back-bearing method. Note that the south (white) end of the magnetic needle is being used to set the back bearing to confirm you are directly opposite the identifiable marker. The compass is set with a magnetic bearing of 140°.
You can use this method if you can see back across the obstacle, such as a gully, to identify the point where you changed direction. Check this before you start the detour. 1. Leave your compass set on the bearing you are travelling on. 2. Locate an identifiable marker, such as a large tree or rock, at the point where your course meets the obstacle. 3. Travel around the obstacle until you are on the other side of the obstacle, opposite the marker. You should be back on your original line of travel. 4. Take a bearing to the marker (don’t adjust your compass when doing this). • If you are directly opposite the marker, it will be the back bearing (original bearing minus 180°) for the original bearing that you were travelling on.
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APPENDIX III | ADDITIONAL INFORMATION
DETOURING AROUND OBSTACLES