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Trevor, you wrote:

> I suspect that a navigator
would discard any observation which led him to a position 45 minutes of
longitude away from his DR. At least, he would be very suspicious of it
and would repeat it next day, then adopt the second observation as the
more accurate one. (The chance of getting two lunars in succession, each
of which had a probability of 1-0.997 = 0.003 is of course 0.000009 or
about one in a million. If you are that unlucky, inaccurate lunars may
be the least of your problems!)

:)) J.K.

But let us consider that lunars were recommended for checking GROSS errors of 
D.R. after many days of sailing - they never could be used for verifying the 
position from one day to another. And facing the real possibility of such 
gross errors, how the navigator was to recognize a lunar observation to be at 
the limit of the 99% error and therefore unusable comparing it with his very 
vaguely known D.R. position?

Happy New Year to you and to all the list.


Jan Kalivoda

   

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