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I've always had my doubts about the actual practicality of a lifeboat
sextant (i.e. that they were intended mostly to impress the
passengers) - since CN would also require a cronometer, an almanac,
and a calculator or sight reduction tables.  If the ship's officers
were bringing those to the lifeboat, then why not bring a good sextant
too?

However, with the sextant alone one could still determine latitude.

A few weeks ago, Andrew Nikitin posted some nomograms for altitude
correction, with the suggestion they could be attached to the sextant
itself.  I suggest one additional nomogram, for reduction of a Polaris
sighting.  I envision a star chart of the polar region, surrounded by
a circular scale, with instructions something like this:

  "Rotate the figure to match the sky, then read the correction from
  the scale directly under Polaris."

I also suggest the offset of Polaris from the north pole in the chart
be exaggerated, so the navigator can confirm the sign of the correction
for himself.  I would also include a worked example.

                - Jim Van Zandt

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