NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2015 Jun 30, 15:32 -0700
Yes, agreed, but why would an electronic compass be much more susceptible to this than a magnetic one? I’ve taken both to the same spot, at the same time, and the electronic one (with the same declination offset) gives the wrong answer. Further away from the power lines, the more in agreement they get. Yet they are measuring the same local field.
Paul Dolkas
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of David Fleming
Sent: Tuesday, June 30, 2015 2:17 PM
To: paul@dolkas.net
Subject: [NavList] Re: Hand Bearing Compass Deviation
Paul,
The short answer is that is the way of the world.
A light bulb gets dimmer the further you are away from it.
For magnetic fields it depends on the geometry of the source.
For a straight wire, say a power line, fields fall as one over the distance from the wire squared. For a current loop as in an electrical device the fields diminish as one over distance cubed so they get small pretty fast.
Dave F
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