The concept of the celestial sphere, system of coordinates, projection of the celestial sphere on horizon, meridian and equinoctial planes, apparent diurnal motion of heavenly bodies, annual motion of true sun and how it affects the day and night phenomena, apparent motion of planets and moon, the concept of time phenomena and keeping (saving) time aboard ships, extracting data from nautical almanac tables, theory of marine sextant, correcting of measured altitude, the spherical triangle PZX and its solution knowing HA, Dec and Lat, intercept method for obtaining the astronomical position line, compass error by time method.