Map, Compass & GPS

Map, Compass & GPS
Wild flowers along Fall Creek on the way to the Green Lakes - Oregon

Tuesday, November 8, 2016

Defining Compass Bearing and Heading


Bearing and heading are two commonly used terms and two of the most misunderstood.  This post will define and review both terms. 

A dictionary defines the word bearing as:

“….horizontal direction of one point with respect to another or to the compass.”

Simply stated a bearing is the angular direction to an object.  Bearings are described in degree increments from either true or magnetic north.

A compass bearing and heading is measured from north clockwise in 360° increments. The point from which the bearing originates is from the center of an imaginary circle.  This imaginary point is the operator.




The direction to an object (a tree, mountain top, or lake) could simply be east or 045° (read and stated as zero four five degrees.)
Outdoor Quest/Blake Miller image
 




Outdoor Quest/Blake Miller image

 



GPS receivers display an incredible amount of data that is important to the hiker.  The GPS compass page, above, predominantly displays bearing information to the hiker. 

In land navigation heading refers to the hiker’s direction of travel.  Heading is a compass direction just as a bearing is.

In the example below a hiker is travelling from point A to point B.  The hiker’s course is the planned direction of travel; about 060° degrees.  Because of obstacles along the way the hiker must change the direction of travel and adjust the heading to arrive at point B.

.Outdoor Quest/Blake Miller image


Because the hiker must change the heading the dashed blue line better describes the actual path through the backcountry.  The hiker’s path may be made up of several headings. In the example above the heading from C1 to C2 could be 100°, about forty degrees different than the planned course.






2 comments:

  1. So if you take a bearing using a compass with a declination adjustment would that bearing now be "true". I am trying to understand the difference between a true & magnetic bearing.
    Thanks

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    Replies
    1. You are on the right track. Adjust the compass first, look at www.magnetic-declination.com for the current declination data. Your compass is now adjusted to provide True Bearings (oriented to true north--the north pole) without requiring further adjustment. The correct bearing value will be read at the direction of travel arrow per your compasses instruction manual.

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