Sunday 19 November 2017

convergence - Applying proper conversion from True to Grid bearing


Assume that Grid North is 1.49 deg W of True North.


Also, the magnetic declination is 13.11 deg.


If I wanted to take gyroscopic surveys (measured from True North) and then convert them to Grid North, what values would be needed to do so correctly?


I've been told to add 1.49 deg to the True North measures to convert them to Grid North measures.


But, I've also been told the opposite, to subtract the 1.49 deg from the True North.


I've also been led to believe that since you are going from True to Grid (in a counterclockwise direction) you would therefore add the -1.49 deg.



Perhaps someone can better explain?




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