Marine astronomy and navigating by the stars | Yacht Club Montenegro

For modern people, who never let go of a phone with the internet and GPS, it is hard to understand how sailors found their way in ancient times. Not cruising near the shore or on a sea trip in Montenegro, but on a journey of many days across the open sea, even in the ocean. Back then there were other methods.

Astronomical navigation and dead reckoning

The first sailors were the people of Egypt and the Phoenicians, and they used astronomical navigation, watching the movement of the Sun across the sky and the stars and working out direction from the heavenly bodies. Sailors of the Minoan civilisation mastered the technique of dead reckoning, working out their route from the distance already covered and their speed. They threw a log into the water ahead of the ship, then made marks as it passed the bow and then the stern, and used that time to work out their speed.

Such measurements were taken every hour with marks on a chart, but frequent errors affected the result, so the Minoans took up astronomical navigation. They sailed by night, guided by the constellation of the Great Bear and the Pole Star, visible in the sky all night long. The star sits above the point of the Earth's axis of rotation, and anyone can use it to tell where north is.

The Antikythera mechanism

This device was invented by the Greeks in the 2nd century BC, a round case with 30 bronze gears on the front and back, with panels of engraved dials and hands. With it sailors calculated the movements of the heavenly bodies. Later the Greeks replaced the mechanism with the astrolabe for measuring angles and calculating the latitude of celestial bodies.

The sunstone

The Vikings found their way at sea by the Sun, but lost their course on stormy days and in northern latitudes. Later they invented the sunstone, a crystal that let them see the Sun even behind the clouds. Holding the crystal up to their eyes, a Viking looked at the line of the horizon, and the closer to the Sun, the brighter the stone glowed. Scientists believe the sunstone may have been a calcite crystal.

Compasses and charts

The first compasses were invented by Chinese scholars in the 7th century, magnetising iron needles by rubbing them with magnetite. By the 11th century sailors were already navigating by compass, watching the 'fish that points south', a wooden fish with a magnetised needle inside. The fish itself floated in a bowl filled with water. Magnetic compasses appeared in the Middle East and Europe by the 13th century. Around the same time sailors realised how important charts were for navigation.

Modern instruments

Today sea trips in Montenegro are completely safe, a well planned route and modern GPS navigation will not let you get lost even on the open sea. At the same time, you can imagine yourself a sailor from the 6th or 13th century, rent a yacht in Montenegro and try the methods described above for yourself.