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    Re: Is there a doctor........I mean a navlist member on board?
    From: Greg Rudzinski
    Date: 2017 Feb 2, 08:18 -0800

    The approximate great circle plot works ok. Not perfect but does serve to shorten the trip vs. the rhumbline. See attached plot done on a Webster's compact world atlas chart using Nicholl's method as dotted line vs. computed GC as dashed line.

    Useful pilot chart which shows a GC route between  Auckland  and Valparaiso :

    http://matdanweather.com/img/pc/07/SP07_2.jpg

    Greg Rudzinski

    From: David C
    Date: 2017 Feb 1, 23:52 -0800

    A pocket atlas just might be good enough to get you home. A pencil width is about 5' nm.

    Greg Rudzinski

    NZers on this forum will remember the red covered NZ School Atlas. My copy is packed away and I could not find it.  The only atlas I have to hand is a slightly too large for the scanner so in the following example the map image is a little out of focus.

    I want to follow the orthodrome to SCL. After some  hunting around I came across a graphical method of plotting a great circle. It was devised  by Airy. The method is very easy although I did not have a large enough compass so used the waist tie of an apron to draw the GC.

    I have attached two files.

    • A page from Nicholls's Concise Guide which drew my attention to the method.
    • A cut from a 1921 atlas showing the GC between Auckland and Santiago.

    A paper describing  Airy's method  is https://cartography-gis.com/docsbca/iccgis2016/ICCGIS2016-34.pdf  The paper contains the comment  Constructing a corresponding arc of circle would require a large enough compass and a map in a small scale.



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