To download charts, open the Main menu > Offline Charts. You will now see an overview map of your current location with several squares covering parts of the chart.
Downloaded areas are shown as green
Areas that are currently downloading are shown as blue
Selected areas are shown in grey
To download new charts
Pan the map to your desired location, and grey areas will appear at the center of the screen
Press on Download to begin downloading the selected areas
The selected areas will turn blue and show a progress indicator
Once the download is complete, the area will turn green
You can download more areas by panning the chart to a new area and pressing Download again. Orca automatically downloads areas around your current location the first time you start the system and when you travel outside your offline chart coverage.
To disable automatic downloading or delete your offline charts, go to Main Menu > Settings > Offline Data. Offline charts can only be deleted in bulk, and there is no way to delete individual offline areas.