NavList:

Bill,

I think Robert's meaning of "external" is
"external to the boat". That he wants to allow only
what you have on the boat + natural (=not man made) objects
and phenomena.  This would prohibit any radio connection
between the boat and man made objects on the shore or in the sky.
So you will probably have to measure some angles.

Actually I remember discussing this question with a friend
(who knew nothing about sextants and navigation, but knew
a lot about modern technology). The friend tried to convince me,
that one can build a device based on modern technology
(that is plastic and electronics, no high precision metal
parts) which will measure altitudes of celestial bodies
more precisely than a good conventional sextant.

I was not convinced by his specific proposals, but he might be
right after all.

Of course, a plastic-electronic device (like a modern computer)
will cost nothing to produce, assuming mass production.

Alex.

On Tue, 4 Jul 2006, Bill wrote:

> > Let's say GPS was never invented,
> > nor any other kind of external electronic
> > system. What would the modern sextant have
> > looked like had it just kept on
> > undergoing improvements?
> >
> > Whatever happened to the "Sextants of Tomorrow" as described in Bruce
> > Bauer's "Sextant Handbook"?
> >
> > Robert
>
> I am embarrassed. I bit on the premise without defining "external."  Given
> the technology necessary for Bauer's sextant and the subsequent blue-sky
> suggestions, what do we exclude?  Earth radio waves (Loran etc.) that don't
> leave the earth and bounce off satellites?
>
> Are man-made satellites external?  If so, would the sun, moon, stars and
> planets not be "external" satellites given the cel nav model where the
> heavens revolve around earth?  A slippery slope?
>
> Bill
>
>
> >


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