A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2018 Jul 13, 15:42 -0700
There's an interesting development in sextant education: It used to be a given that nearly anyone could read a sextant scale and, with only a little effort, read the sextant micrometer. But lately I've discovered that many people when first using a sextant a thrown off by something very simple... Suppose the angle measured is 11°56'. Many people are inclined to read this angle as 12°56' because the main index pointer is pointing at 12! Of course this is no different from reading a common analog clock or watch: we don't advance the hour until the "little hand" is fully past the next number and when in doubt we judge that by looking at the minutes. Same with a sextant: when the minutes of arc are approaching the next degree, reading for example in the high 50s, then the degree from the main scale is the one just below the pointer.
Sounds obvious, right?? Even painfully obvious, but times change, and familiarity with reading instruments with scales is becoming rare. It's almost as if we have to teach potential navigators how to read a clock. Just something to be aware of if you try to teach sextant basics.