The dead-reckoning line on his chart is important to the navigator because it indicates at a glance the theoretical position of the ship, the track the ship should have followed, and the direction in which the ship is traveling. For example, the navigator whose ship is equipped with a radio direction finder can determine the bearings of radio transmitting stations on shore. Special radio beacons for navigation are established at lighthouses , lightships, and prominent points along coasts. Radio bearings may be plotted on a chart to obtain a fix. A variety of other electronic aids to navigation are in use or under development.
Radar is also of value, especially for a ship near the shore.
Consol, by contrast, is designed for operation over relatively long ranges. A ship at sea can obtain a fix on its position from Consol shore stations with the use of an ordinary radio receiver. For centuries sailors have guided their ships across the oceans by celestial navigation, or nautical astronomy. This is the art of finding position by observing the sun, moon, stars, and planets. As they journey for some distance, travelers observe that the celestial bodies appear to change their paths across the sky and to rise and set at new points along the horizon.