NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Impressed with the Raft Book
From: John Huth
Date: 2010 Feb 1, 09:29 -0500
I tried to estimate the uncertainty from this method. Refraction is definitely one of them, although there are ways of guesstimating refraction effects that will probably be good to maybe 5 arc-minutes. If you don't correct for refraction, you can be systematically off by 30 arc minutes or more.
From: John Huth
Date: 2010 Feb 1, 09:29 -0500
The rising and setting angle of the sun can also be a nuisance.
Certainly low lying clouds, fog banks etc will be a big issue.
My estimate was that under ideal conditions one could expect an accuracy of about 20 arc-minutes, but you have to put in a refraction correction - ie. know when to start the clock and when to stop the clock.
Doesn't a watch count as an instrument?
On Sun, Jan 31, 2010 at 10:31 PM, Mike Boersma <mike.boersma@gmail.com> wrote:
Frank Reed wrote: "But in the real world, the observed times of sunrise and sunset are variable for a number of reasons and those variations will significantly diminish the accuracy of this approach to finding latitude."
What might these reasons be? Refraction? Clouds?
"It's certainly not a worthless method, but its accuracy is low."
This method does not appear to be more or less accurate than other no instrument or crude instrument methods of determining latitude.
I would be surprised if results by this method were better than 1/2d when attempted under real world conditions.
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