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    Re: Great Circle puzzle
    From: Peter Hakel
    Date: 2013 Oct 27, 19:17 -0700

    Using Sean’s numbers I get the following:

    Initial GC course from spreadsheet sailings.xls:
    30.284° (add 180°): 210.284°

    GC distance from spreadsheet:
    4878 nm (subtract from 21600 nm): 16722 nm

    GC north vertex (from spreadsheet):
    N 62° 49.4’
    E 138° 23.7’

    GC south vertex (reverse latitude, subtract 180° from longitude):
    S 62° 49.4’
    W 41° 36.3’

    Waypoints in increments of 15° of longitude (see chart, I just eyeballed the latitudes there) are computed in spreadsheet waypoints.xls.

    Here the total length is computed to be 17131 nm, but that result works with rhumb-line segments between the GC waypoints, which is why it comes out a little larger than the GC value of 16722 nm.

    Peter Hakel

    PS. Some of my numbers could/should be rounded to a smaller number of significant digits, but I decided to show them essentially as computed.

    Depart: Gwadar, Pakistan 25°05'N, 62°18'E; heading ~207°.
    Pass between Madagascar and Mozambique.
    Pass between Nordenskjold Coast, Antarctica and the Hermite Islands, Chile.
    Arrive: Olyutorskiy zaliv, Russia 59°50'N 166°21'E.
    Total Distance: ca. 17,000 nm
    -Sean C.



    File: 125389.waypoints.xls
    File: 125389.sailings.xls

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