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    Re: Great Circle Sailing Chart
    From: Gary LaPook
    Date: 2016 Jan 15, 01:03 +0000
    I'm confused. The chart you posted is too small for me to read. You say that the diagram is for determining the "great circle bearing of the destination from the point of departure" but that is easily determined by measuring the initial great circle course at the nearest meridian printed on the chart to the departure. If it is determining  the rhumb line bearing then it is apparently a graphical way of determining the "conversion angle," table 1 in Bowditch.


    From: Robin Stuart <NoReply_Stuart@fer3.com>
    To: garylapook@pacbell.net
    Sent: Thursday, January 14, 2016 1:02 PM
    Subject: [NavList] Great Circle Sailing Chart

    The NGA Chart 17 "Great Circle Sailing Chart of the Noth Atlantic Ocean" has a graphical device in its lower right hand corner for determining the great circle bearing of the destination from the point of departure. The instructions call for locating the point on the great circle (a straight line) at 5°, 20° or 30° longitude difference from the point of departure. This point and the point of departure are then located on a pair of curves in the diagram. A line drawn through the points gives the bearing. What are the principles by which this works?
    Robin Stuart

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