ASA Celestial Navigation
Standard
Prerequisite:
None
General Description: Able to demonstrate the
Celestial Navigation theory required to safely
navigate a sailboat on an offshore passage. The
practical application is conducted in the Offshore
Passagemaking Standard.
A Certified Sailor has successfully
demonstrated his or her ability to:
 Convert longitude into time.
 Convert standard time and zone time to GMT
and vice versa.
 Calculate the zone time given longitude.
 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 altitudes.
 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 using a
navigation table and show all appropriate work.,
 Plot celestial lines of position on a
Mercator projection or on a universal plotting
sheet
 Calculate the times (ship's 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 using a
running fix (sunrunsun).
 Calculate the true bearing of a low altitude
celestial body in order to determine the error
and deviation of the compass.
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