Thoughts on Astro Navigation
Pemandia
Peter Fabricius
Fri 19 Feb 2016 12:06
In preparation for our trip to the Azores I have been relearning astronavigation. "Why" I hear you ask "are you doing that in the GPS era?" Well, it is true that most of us have at least one GPS, many have a specific back up GPS and lots of us have multiple (probably more than we know about) in phones, tablets etc.
First of all it is fun and second I think it is a sensible back up. I'd be interested in this regard about what the experts think. I seem to remember hearing that the RN had stopped routinely teaching astro and then reintroduced it. Batteries fail, even if satellites are now reliable!
I first learnt about it as a teenager when I taught myself at school and did A level navigation. I learnt it all from the Admiralty Manual of Navigation Volume 2 and the other day I found the hard back notebook I made all my neatly written notes in. I love the style of both book and notes: just as I remember maths and physics classes "consider the triangle PXZ and examine the angle ....". Such a good way to learn! Subsequently I used the wonderful but probably now out of print Mary Blewitt's Celestial Navigation, also a masterpiece. If either of these books goes missing from my shelf I will know a blog reader has pinched it!
So I have dusted off the notes and remember the principles - gosh it is easy to make a mistake when you are tossing around and perhaps a tad seasick! So I have cheated a little and have a brilliant app on my iPad that does the whole thing and more. Yes that still needs a battery so perhaps I will fork out for the full Nautical Almanac and some Air Navigation sight reduction tables. These cover a 5 year 'epoch' and my existing copy was for the late 1980s. I wonder how much changes?