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Please Frank - you really are a wonderful upstart, I would really hope
that all of us are well aware that "dead" reckoning is a corruption of
"deduced" reckoning, at least so the story goes.

On Mon, 6 Dec 2004 19:32:39 EST Frank Reed  writes:
> Ken M wrote:
> "I have to do a lot of
> double checking to eliminate errors but I think  that in the days
> when log
> tables were in common use and arithmetic  calculation was heavily
> drilled
> at school, a lunar could easily be done in 30  minutes by an
> experienced
> navigator."
>
> I agree that they could be done with relatively little time. I would
> say 20
> minutes with a little experience, but the idea that this was "common
> math" I
> don't believe at all. The only thing a navigation instructor could
> take for
> granted in his students was knowledge of basic addition and
> subtraction. But
> really, that's all you need. Sometimes a blank slate is easier to
> work  with.
>
> And:
> "Confidence in the result would come from comparing the lunar
> longitude  with
> the ded reckoning."
>
> Ded instead of dead? That might be another interesting topic for
> discussion.
>
> But to your point, the comparison with the DR longitude was the ONLY
> way
> that navigators could get confidence in their results and sometimes
> too much
> confidence. It's easy to subconsciously "adjust" lunars, both in the
> observations and the calculations. How often did navigators work
> back through  their
> calculations and find an error when none was present in order to
> bring  their
> lunar longitude into line with their DR longitude?
>
> Frank R
> [  ] Mystic, Connecticut
> [X] Chicago, Illinois

   

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