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    Re: True vs Magnetic
    From: Paul Dahlgren
    Date: 1999 Jul 23, 9:35 AM

    I do something similar for coastal navigation in areas of constant
    variation with a "string protractor."  This is a plastic protractor, about
    4-inches square, with a piece of string (actually a piece of tarred
    marline) fastened in the center.   Simply place the device over point A,
    and stretch the string to the center of nearest compass rose.   Observe the
    magnetic reading on the rose, and set this same reading on the protractor.
    Then swing the string to point B and read the magnetic heading.  Simple to
    make and simple to use.
    Paul Dahlgren
    Message text written by Navigation Mailing List
    >As a side note, my favorite course-plotting tool is the Pocket Instant
    Navigator.  The PIN consists of two plastic disks and a pointer all riveted
    together so they can independently rotate.  The base disk has a 1/4" square
    grid of N/S and E/W lines imprinted on it as well as a 0-360 degrees marked
    around the periphery.  One drops the PIN over the starting point for a
    course (the axle rivet is even hollow so one can see the point through the
    PIN), aligns the base disk N/S by aligning the grid with the meridians and
    parallels on the chart, spins the pointer to the destination (or along the
    course line) and reads the course.

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