Celestial Navigation Standard
OBJECTIVE
To be able to demonstrate the celestial navigation theory required to safely navigate a sailing cruiser on an offshore passage. The Standard is applied practically in the Offshore Cruising Standard.
PREREQUISITES
Coastal Navigation Standard.
ASHORE KNOWLEDGE
The candidate must be able to:
- a) Convert longitude into time
b) Convert standard time and zone time to GMT and vice versa
c) Calculate the zone time for a given longitude, and
d) Calculate the chronometer (or watch) error given a previous error and the daily rate - Apply the corrections for index error, dip of the horizon, and total correction to convert sextant altitudes of the sun, stars, planets, and moon to true altitude;
- Calculate the time of meridian passage of the sun and calculate the boat's latitude from the observed meridian altitude of the sun;
- Determine the latitude at twilight by means of the Pole Star;
- Solve the navigational triangle by means of navigation tables (electronic calculators may be used as a supplementary method only);
- Plot celestial lines of position on a Mercator projection or on an appropriate plotting sheet;
- Calculate the times (ship's time and GMT) of sunrise, sunset and twilight;
- Determine the approximate azimuths and altitudes of the navigational stars and planets at twilight;
- Calculate and plot the lines of position obtained from observations of several celestial bodies at twilight and thus find the boat's position;
- Advance the LOP obtained from a sun sight to another LOP obtained from the sun at a later time and find the boat's position by means of a running fix (sun-run-sun);
- Calculate the true bearing of a low altitude celestial body in order to determine the deviation of the ship's compass.
