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    Re: Azimith forumula for Great Circle sailings- having problems
    From: Samuel L
    Date: 2014 Dec 24, 04:18 -0800

    Gary,

    Unless I'm really, really, really wrong the Azimith is 3.917400689 and not -3.917400689. Forget about the places to the right of the decimal for the moment.

    The coordinates of both positions were plotted on a UPS and gave the same result of +3.917d

    Several online great circle sailings calculators gave the same result.

    Peter Hakel's Sailings.xls spreadsheet gave the same result of +3.917d

    I think the error occurs when the LHA (Difference in Longitude) isn't examined for a greater or less than 180d value. If a negative sign is applied to the LHA when using the formula then the answer comes out correctly.

    I've read your lengthy comments but learn only by trail and error. Thus, if the GPS says such and such a figure and Gary says something contrary....for the moment I'm going to work with the GPS figures until study and practice shows otherwise. It's like the "rounding up or down" situation I had a few months ago.

    Would you please show me how in the world you arrived at a negative Azimith?

    Sam L.

     

       
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