How does Coastal Explorer get compass variation?
Coastal Explorer uses the World Magnetic Model to calculate magnetic variation based on your location and the date.
Very interesting. Thanks! So I take it CE doesn’t use the variation information imbedded in the charts?
I know the variation is given under the Conditions tab. Is it used in any calculations if I have input from a Heading Sensor?
Correct, the variation indicated in the charts is not used for anything other than to show in the chart properties.
If you have a heading sensor that only provides magnetic headings, then Coastal Explorer will use the calculated variation at your position to convert those headings to true so the boat symbol can be oriented correctly and for heading instruments and other heading-related calculations when you have your “Settings > Measurements > Bearings” option set to “true”.
Similarly, if you have a heading sensor that only provides true headings (such as a GPS compass), then Coastal Explorer will use the calculated variation to convert those headings to magnetic if your Bearings option is set to magnetic.
Thanks. In my case I use an Airmar 220WX as the heading sensor. It sends both true and magnetic headings. Settings>measurements>bearings is set to “true”. On the screen I see both True and Magnetic headings, with magnetic in “gray”. Are both from the heading sensor, or is one calculated?
When a heading sensor provides both magnetic and true, then Coastal Explorer will use those headings directly rather than applying its own variation.