NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: True vs Magnetic
From: Paul Dahlgren
Date: 1999 Jul 23, 9:35 AM
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. <