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Author
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Topic: IN09-0007
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jbido1205
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posted April 28, 2022 10:06 AM
Do I need to convert the given Course Direction from
Magnetic to True before plotting the directions steered?
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David Burch
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posted April 28, 2022 11:56 AM
You can do that if you choose to for any reason, but otherwise the standard procedure would be use the compass rose to get magnetic bearings.
I see your question, because we are using a constant 20.0ºE for the variation, the nearest rose on the printed chart could be off a bit. The one to the north is at 19.75º, but that should be fine for this.
Alternatively, just add 20º to each of the headings and plot true bearings.
A related question comes up if our plotting tool of choice is the weems paralell plotter. That device is in large part intended to be used with true bearings, so with that tool the standard procedure would be to convert to true first. That tool does not work as well as parallel rulers for reference on a compass rose.
From: Starpath, Seattle, WA
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David Burch
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posted April 28, 2022 11:58 AM
Note this seems to be a question about a course quiz, but i just noticed it is in the public forum. I will move a copy to the Student Discussion forum and we can carry on in that one.
From: Starpath, Seattle, WA
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Topic Closed
