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    Re: Trans Atlantic
    From: Brad Morris
    Date: 2012 Oct 24, 13:08 -0400

    Correct Andres!  I believe Kevin indicated that the course is corrected once per hour to the new rhumb line.

    Kevin could check before and after a round of twilight sights, to determine the average course.  I think this to be over working the problem, wouldn't you agree?  There will be a negligible difference in position.  IMHO, frankly too small to be noticed.

    A far more complicated matter would be to advance several sun LOPs, when the course is changed once per hour!  The error term here will be significant compared to a 10 nautical mile positional error window, and worthy of consideration. 

    Since each lop would need to be advanced and rotated from the course at which it was taken to the course of advancement, we have an interesting problem.  Would a linear algebra matrix rotation, with the rotation angle being the delta between the courses work? 

    Best Regards

    On Oct 24, 2012 11:48 AM, "Andres Ruiz" <navigationalalgorithms@gmail.com> wrote:
    No problem, usually a GC route is divided in a number of rhumb line tracks, and used to steer.

    2012/10/24 Brad Morris <bradley.r.morris@gmail.com>

    The deviation between a true, constantly curved great circle course and a straight line approximation will be far less than your measurement uncertainty, especially for a running fix whose total duration is less than one hour.

    In other words, I would not worry about it and just assume a straight line course, instead of a curved course.

    Andrés Ruiz
    Navigational Algorithms
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