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Subject: Re: True vs Magnetic
From: Paul Dahlgren (Dahlgren@XXX.XXX)
Date: Fri Jul 23 1999 - 11:34:56 EDT
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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