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Doug,

That statement: "It's such an appealing idea that many of the best navigation
authorities have been blind-sided by it" IS pretty vague. I really didn't
know what to say about the fact that a majority of navigation authorities signed
on to the idea of using lines of position to get GMT from the moon. Every one
of them knows that the moon being east or west of you doesn't mean you are
west or east of her. The earth is not flat. Nor is it cylindrical. They also know
that the accuracy of altitudes taken at sea from a small boat can be
extremely uncertain.

If you want to use the idea, do it on land with an artificial horizon. And be
sure to catch the moon when her horns are pointing more or less strait up or
down. If you work it with time sights (as the eighteenth and nineteenth
century advocates proposed) you'll save the slippage of accuracy that goes with
plotting. You'll also save work.

Bruce

   

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