The day's work

Morning twilight: a round of three stars, reduced and plotted for a fix. Mid-morning: a Sun sight for a line. Noon: the meridian altitude for latitude, the morning line run up for the running fix; the day's run and the noon position in the log. Afternoon: another Sun line. Evening twilight: stars again. Between them the dead reckoning carried forward from each fix by course and distance, so that every sight is checked against an expectation and a wild one shows itself.

Twelve evenings end here; the sea continues the course.

The fix at twilight comes from what?
What is every new sight checked against?

Show the answers
  1. The fix at twilight comes from what? A round of several stars reduced together Several bodies taken within minutes give crossing lines without a run between them.
  2. What is every new sight checked against? The dead reckoning carried from the last fix An expectation makes a blunder visible.

The twelve evenings

  1. The celestial sphere
  2. The sextant
  3. Time and the almanac
  4. Correcting the altitude
  5. The noon sight
  6. Latitude by Polaris
  7. The navigational stars
  8. The intercept method
  9. Plotting the position line
  10. The running fix
  11. The Moon and the planets
  12. The day's work

A demonstration: the course, its tutor and its loft are invented; the navigation is real. Built by plinth from EDN and Markdown; the quizzes are checked in the page and send nothing, and the only thing kept is your progress, in your own browser.

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