NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Accuracy of backpacking compass
From: Robert Eno
Date: 2012 Nov 5, 15:30 -0500
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From: Robert Eno
Date: 2012 Nov 5, 15:30 -0500
I've been using them for years; mostly Sylva
compasses which are intended for use with maps.
In my experience they are accurate enough if you
use them intelligently. At the risk of coming across as pedantic, if you you are
on a high hill and take a few bearings that put you in a valley, use the map to
identify your real location, which should be very close to your fix, unless you
made a gross error in taking your bearings or were wearing a magnet around your
neck.
The trouble with backpack compasses, at least in my
experience, is that they can be deviated by the local geology. Even at that, I
have never been hopelessly lost using a small compass on land, accompanied by a
good topo map.
Robert
----- Original Message -----From: Apache RunnerTo: NavList@fer3.comSent: Monday, November 05, 2012 8:37 AMSubject: [NavList] Accuracy of backpacking compass
I was wondering if anyone has insight into the accuracy of typical backpacking magnetic compasses. By these I mean the hand-held variety.In working with students (and myself), we got a fairly large number of non-intersecting triangulation fixes when we went to three bearings. In this case we assumed +/- 5 degrees of accuracy, but I think that the actual uncertainties are larger than that. The most difficult part is the physical size of the compasses and the difficulty in lining it up in the direction of a target. If I work with something like +/- 10 degrees, I feel a bit more comfortable in my estimates, but that begins to sound like a ghastly large uncertainty. Perhaps somewhere between 5 and 10 degrees?Obviously this isn't the arc-minute precision one hopes for with well-built sextants, but for a person who brings along one of these compasses on a backpacking trip, it's helpful to know the uncertainty.
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