Ebook: Celestial navigation by H.O. 249

Cornell Maritime Press, Centreville, Maryland, 1994. 102 p. — ISBN 0-87033-191-4.

In the summer of 1971 there were two boat arrivals on the east coast of the Island of Oahu that puzzled me. The first was a sailboat from California in the 35-40-foot range that was home-built and crewed by a half dozen or so young people of college age. When interviewed by a local reported and asked how they have found their way, the skipper answered that they have used a ten-dollar transistor radio with some directional qualities, and had started west by a little south sailing until they picked up Honolulu radio stations, and then homed in on them. They had had no other navigational equipment except a compass."Any kind of boating can be fun," the author points out, "racing around the marks, or coastwise cruising where there is almost always at hand visual reference ashore from which bearings can be taken for locating one's position and thus finding one's way home. Severing these ties with land, however, offers a new kind of fun, a new kind of freedom, a freedom from dependence on land."
Here is a basic beginner's book, introducing the tyro to the tools, the vocabulary, and the techniques of celestial navigation. Among the recommended tools are the H. O. 249 Tables, the most widely used among amateur navigators at sea, because of their simplicity.The ability to determine one's position at sea both liberates the sailor from the land and enables him to find his way to his destination. If you can read, add and subtract, understand angles, and use a protractor, you can learn to navigate in your armchair or at sea from Celestial Navigation by H. O. 249.ContentsIntroductory note
Celestial navigation for the beginnerWhat you will need
Time by Radio
Types of Sextants
Nautical Almanac
H.O. 249 Tables
Other MaterialsLanguage
Latitude and Longitude
How Latitude Is Plotted
How Longitude Is Plotted
Declination (Dec.)
Greenwich Hour Angle (GHA)
Local Hour Angle (LHA)
Greenwich Mean Time
Sidereal Hour Angle (SHA)
Altitude (Alt.)
Zenith
Zenith Distance (ZD)
Azimuth (Zn)Taking a sight
The Sextant
Altitude Corrections
Instrument Correction (1С)
Height of Eye (Dip)
Correction (Refraction, etc.)
Additional CorrectionsDetermining latitude
Latitude Formula
Time of Noon
"d" Factor
Standard Times
Taking the SightLine of position (LP)-fix
Step by Step to Line of Position
Work SheetPlotting a line of position (LP)
Plot Sheet
The Problem PlotFix
Plot Sheet
Work Sheet
Plot Sheet
Almanac Page
Almanac Page

Other members of the solar system
Venus Work Sheet
Venus PlotMoon
Work Sheet
Correction Tables
PlotStars
Polaris
Polaris TablesThe three star fix
Star Work Sheet
Three Star Plot
Star Plot Using H.O. 249, Vol. IIA start in star finding

Polishing your skill
The Navigational Triangle
Computing He and Zn by Trigonometry
Other information in Almanac
Refining the Noon Sight
The Direct Plot
H.O. 214
H.O. 229