Humminbird Side Imaging Forums

General => General Discussion => Topic started by: RGecy on April 06, 2009, 10:47:54 AM

Title: Understanding Map Offset
Post by: RGecy on April 06, 2009, 10:47:54 AM
There was some discussion recently on setting the Map Offset and how this affects waypoints created previously and those created while in the Map Offset.

The Map Offset will only adjust the view of the map visually.  It does not change any GPS coordinates, tracks, or waypoints.  If you created a waypoint at a Stump for example and later changed the Map Offset, the GPS coordinates of the Stump remain the same and you will be able to navigate back to that stump.

GPS coordinates are the real world and the map is only a visual display.  Maps are frequently wrong and I am sure Navionics does everything they can to adjust the errors that are found.

If you would like to test this feature, try this.

While the boat is still (in the driveway would be good), mark a waypoint at your current position and take note of the coordinates.  Now go into the Chart Menu and set the Map Offset.  Move the cursor to the right say 500' or 1000'.  Something rediculous to see the change.  The map will adjust itself.  Your boat has not moved and when you view the map, you are still right next to or on top of the waypoint you created.  Also, look at the coordinates of your current position.  The GPS numbers do not change.  (They may fluctuate a little depending on which GPS reciever you have and how well its seeing the satelites.)  Now create a new waypoint right next to the other one and take note of the coordinates.  Go back and reset the Map Offset and look at the position of the two waypoints.  They will remain in the same position.

I hope this is a clear explanation.  Please let me know if you guys have any problems or questions.

Thanks,

RGecy

   
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