NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Hanno Ix
Date: 2015 Jul 14, 10:10 -0700
On the cot() scale at around 45 deg the marks are the closest, and the distance
between, say, 44 deg and 45 deg may be about 30mm. I am proposing 30 additional
small marks for 2 arc min steps which makes the distance between them 1mm
which should be discernible from nearly 3 m away.
So, if I assume a viewing a distance between eye and Flat Bygrave about 300 mm
the visibility of the proposed marks are not affected by the eye's acuity limits at all.
substantially improved re: readability if you were to add 2 arc min marks.
This improvement would bestow a much greater utility to it, particularly in
emergency situations.
BTW, I don't like calling these "emergency navigation" systems. That implies using a less accurate system for celestial navigation in emergencies whose only advantage is that they are compact so as to fit in a ditch bag. This seems to say that you use the most accurate standard system everyday, carrying the entire set of HO 229 in your small boat, and will use the bastardized system only in an emergency. What we are actually talking about are different methods of clestial navigation, that just happen to be compact, but that should be used every day for normal celestial navigation, leaving the entire set of HO 229 at the dock. Most navigators have apparently shifted to using HO 249 to save the considerable space (and weight) of the ultimate set of tables, HO 229, and find the level of accuracy in HO 249 accptable for practical navigation and the Bygrave and Hav-Doniol (and others) provide the same level of accuracy in very compact forms.
gl
