NavList:

Thank you Wolfgang for the book recommendation.  I see it is available on Amazon at a modest cost.  I will look forward to reading it.

A silly coincidence...

A few years ago, like many others as we age, I realised that my short term memory was starting to show signs of weakness.  I decided that I would engage in mental exercises to keep the brain fresh.  My celestial navigation had involved tables and then calculators, and these too had faded away after I had access to satellite-based alternatives.  I was a practical, rather than a theoretical, navigator.

So when looking for a new mental challenge, I decided that I would learn spherical trig. and work sights in the manner of the late 18th century navigators - no sight reduction tables and no calculators.  This was purely as a form of mental exercise, but in a field I enjoyed and was interested in.

And that, after some time, was what brought me to this community.

Did it work? Er... sorry, what was the question again?