NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Shadow sights for longitude
From: Peter Monta
Date: 2018 Jan 12, 20:43 -0800
From: Peter Monta
Date: 2018 Jan 12, 20:43 -0800
Increaseing shadow length will not improve the accuracy. As has been noted the accuracy is limited by the sun not being a point source of light.
Would "shadow sharpeners", as used by the sundial people, be of any help? A moderately-large pinhole is placed in the shadow near the surface, then moved until the image shows a half-sun. Then you're centered at the halfway-point of the shadow, which would otherwise be difficult to locate by eye.
Cheers,
Peter
