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Frank said that he didn't know anyone who liked them (or words to that effect).

Given that the NA tables  system is taught in Power Squadron
navigation classes, I would have thought that the biggest hurdle of
any system - becoming familiar with the method - would have been
overcome and made this method popular.

The NA sight reduction system has the advantage of being angles all
the way, so you are not changing in and out of logs, and once you get
the hang of it, this method seems to be as quick as any.

Any thoughts on why it is not popular?

Lu Abel says that the "Law of Cosines" is what is being taught to the
Power Squadron these days as the principal method of sight reduction.
I went and had a look at the Power Squadron website and sure enough,
in the 'Nautical Tools' section, there is a handy little online sight
reduction program, showing the formulae used - and presumably taught
in Power Squadron classes.

Now, there may be good reasons why the NA sight reduction tables are
not popular, but as was pointed out some years ago by Herbert Prinz,
the formulae given in the NA for sight reduction using a calculator
are the best formulae available for a number of reasons and I am
surprised that the Power Squadron do not teach those instead. The
formulae for Hc is the same, but the Power Squadron formula for Zn
blows up in polar regions, whereas the NA version does not.

Geoffrey

   

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