jdc
Well-Known Member
Plotting sheets for tropical or temperate zones are easily made on normal graph paper as an approximation to a Mercator projection, and up to about 65N (or S) give acceptably small errors. However for a voyage to the arctic last year I made some sheets good to 80N and have put them here http://www.awelina.co.uk/sextant/plotting_sheets/ in case of interest or use to anyone else.
After some thinking about the appropriate projection I chose Transverse Mercator. I'm not sure that this is mathematically ideal but is easy to construct and preserves shape and scale very well so I felt it best for simple sun-run-sun fixes in the normal way where one isn't optimising distance sailed but navigating to a particular place. I found few references in literature to astro-nav in these altitudes so made it up from scratch hence comments are welcome, as always. I did use (some of) them, getting particular delight from taking a midnight-sight.
After some thinking about the appropriate projection I chose Transverse Mercator. I'm not sure that this is mathematically ideal but is easy to construct and preserves shape and scale very well so I felt it best for simple sun-run-sun fixes in the normal way where one isn't optimising distance sailed but navigating to a particular place. I found few references in literature to astro-nav in these altitudes so made it up from scratch hence comments are welcome, as always. I did use (some of) them, getting particular delight from taking a midnight-sight.
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