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    Re: Gps
    From: Dan Allen
    Date: 2003 Feb 10, 18:32 -0800

    On Sunday, February 9, 2003, at 08:00 PM, Gary Harkins wrote:
    
    > Did it show both the rhumb line and Great Circle or did it show the
    > rhumb line but follow a Great Circle?  I was just playing with a
    > Garmin unit that was still on the shelf of our local Boaters World and
    > it only showed the rhumb line even though it was going to follow a
    > Great Circle.
    
    Nowhere in the Garmin GPS settings and options are the terms rhumb line
    or great circle used.  However, if you create a route with two points,
    Seattle and London for example, the map will show a great circle route,
    and the course given will be the initial great circle course
    (approximately 34 degrees in this example).  This course is curved when
    seen on the map in this example.
    
    The rhumb line is a bit tricky to find.  First make sure that the route
    you just created is made active.  While viewing the main map view press
    menu to see "Setup Map" (this is on my Garmin GPSmap 76), and then find
    the "Line" tab within "Setup Map".  On that page there is an option
    called "Bearing Line".  If you turn this on you will see a rhumb line
    that will be drawn at approximately an 88 degree angle for our
    particular route in this example.  This is the rhumb line bearing from
    your current location to the next waypoint or to the destination.  This
    line appears straight when seen on the map in this example.
    
    Garmin Glossary:
    
    Bearing: the angle from your current location to the next waypoint or
    to the destination
    Course:  the angle from your start to your destination,
              or from your last waypoint to the next waypoint
    Heading: the direction your bow is pointing
              (if no wind or currents this is the same as track)
    Track:   your direction of movement relative to the ground
    
    Dan
    
    
    

       
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