Navigation around Natural Barriers

 Occasionally, it will be necessary to navigate around unexpected impassible barriers such as lakes, swamps, or nuclear test facilities. Offset navigation is not an easy task and will require some special planning and execution.

Your goal, if conditions allow, is to plan and navigate a rectangular course large enough to circumvent the barrier.  At the optimal site in your course, plot a new leg that lies at a right angle (90⁰) to your present course (Distance 3 on diagram).  Continue on this course until you again have free approach.  At this point you will turn another leg at right angle (90⁰) towards your course direction and continue along this leg (Distance 2) until you can easily rejoin your original route.  To rejoin your route, turn another right angle (90⁰), now heading back to join your original route (Distance 4).  Continue along this route, the same distance you traveled on the first leg (Distance 3) of your detour.  Assuming your plotted course was a straight line through the barrier, you are back on original course. 

If the course through the barrier is not straight then the navigator will have to offset the complex traverse by a convenient amount.  If possible, start the offset at a (90⁰) as shown in the diagram, although it is not essential for you success.

Set your course and traverse along course D-1 for the distance necessary to circumvent the obstacle; when you reach this point then resume the original course.  When you have passed the obstacle, reset the original course by traversing along D-2 at a bearing 180 degrees from D-1, but at the same length.  When you reach the end of this traverse, you can then resume the original course.

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 Our thanks to the Elko County, Nevada Sheriff's Posse Search and Rescue Team for this valuable information
 http://www.ecsposse.org/