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» Online Classroom   » Inland and Coastal Navigation   » Public Discussion of Inland and Coastal Navigation   » OpenCPN Variation, Magnetic & True

Author Topic: OpenCPN Variation, Magnetic & True

 - posted December 07, 2023 01:42 PM      Profile for Debzazzo           Edit/Delete Post 
I’m continually getting confused with the OpenCPN settings on Variation, and whether entering the +20 E entry in settings makes all the Headings on the chart show as True? Or shows Headings as Magnetic and then +20 E needs to be added when charting?
I’ve watched a lot of the training videos and it looks like sometimes the +20E is being manually added during charting, and sometimes it is entered in the OpenCPN as a setting…Thanks for help [Wink]

David Burch

 - posted December 07, 2023 02:43 PM      Profile for David Burch           Edit/Delete Post 
OpenCPN has two ways to accept a mag var. You can use the plugin WMM (World Magnetic Model), which I think is installed and running as default. This is normally, for your own on the water navigation or planning, the logical way to operate. It will create and use the best mag var for any time or place.

For our work in the classroom, however, this is not a good choice, because we are working with an old chart and we are using for all locations on that chart a fixed value of 20E.

Thus for our work, Step 1 is go to options (gear icon) then Plugins tab, and then disable WMM (if it is on).

Then Step 2 go to Options / Display / units.

Step 3. Confirm that you can enter a number into the Set mag var input field. If not, then close the program and reopen. Sometimes disabling the plugin does not open this field as it should.

Step 4) once you can enter a number there, enter 20.0. this positive number means 20.0 E

Step 5. Then you have the choice with a check mark to show true only, magnetic only, or both.

This you have to experiment with for personal preference. Sometimes showing both can lead to a mistake in some displays, but as long as you are aware of what you have asked for, it should be fine.

Please let us know if this resolves your use of that function.


From: Starpath, Seattle, WA
David Burch

 - posted December 07, 2023 05:06 PM      Profile for David Burch           Edit/Delete Post 
Just realized this is posted in the public forum. I will move it to the Student Discussion forum and we can continue there.
From: Starpath, Seattle, WA

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