ANCIENT SEAFARING TECHNIQUES BEFORE THE 12TH CENTURY CE
ANATOMY OF A SEXTANT
Used to help stop glare and make it possible to position the Sun on the horizon through your telescope.
The purpose of this is to capture the Sun or pole star; the angle at which it is located will then be used to establish your position.
This is the measurement readout, showing the angle of the index mirror when the Sun has been positioned correctly.
The viewing point through which you aim at the horizon, before moving the index bar to align the Sun and establish latitude.
Used to move the mirror. The gap is the viewing point for determining the Sun’s altitude relative to your current position.
First invented as a device for divining as early as the Chinese Han Dynasty (around 206 BCE), the compass was adopted for maritime navigation by the early-12th century CE. However, we know that many cultures were sailing well before this — so how exactly did they navigate Earth’s vast oceans?
Exploring by day
During daylight hours, you will be able to make out points of reference on land — such as mountains or large structures — as well as follow the path of the Sun itself. When possible, do as the ancient mariners would and stay within sight of the coast and use these landmarks to guide you. This also means you’re never too far from terra firma for supplies.
Exploring by night
Once the Sun goes down and the coast is no longer visible — and given the general lack of visibility -moving closer to the land is not recommended due to the increased risk of running aground in shallow water and other dangers like reefs. Instead grab your star charts and look upwards to make use of the night sky.
Find the North Star
The most common point of reference in the night sky for sailors has always been the North Star (Polaris), which sits directly above the Earth’s North Pole. It’s relatively easy to find given that it’s one of the brightest stars in the sky. It can also be located by following down from the Big Dipper (Ursa Major) constellation which sits above it.
That is not to say the North Star is the only celestial body to guide you — there are many other stars that move little and don’t ‘set’ that can serve as great guides when you’re out at sea. For example, take advantage of constellations Cassiopeia and the Big Dipper — either side of the North Star -to more accurately gauge your heading.
Sound out your depth
Another good reference for navigators is the ocean’s depth, as this will give you a good idea of how far you are from land. To establish how deep the water beneath you is, you need to drop a sounding weight into the sea, with its attached rope serving as measurement. As well as depth, these devices can also collect samples from the ocean floor.
Let birds lead the way
If for some reason you lose sight of the coastline during the day — and therefore have no stars to refer to — you can turn to the animal kingdom. A clever technique as a final resort is to release birds that are kept on board and then follow them as they fly towards land. This is something the Vikings did, using ravens to take them to new shores.
How not to navigate
Having found fame on his explorations in Asia for the Egyptian ruler,
Ptolemy VIII, the Greek navigator Eudoxus of Cyzicus later became intrigued by the African coastline, when on the return journey of his second voyage to India, he was blown south of the Gulf of Aden.
On this detour he discovered the remains of a ship and, from its appearance and the details gathered from natives, Eudoxus concluded it had originated from Spain and had, albeit unsuccessfully, circumnavigated Africa.
This inspired him to attempt rounding the continent himself. Setting off from the same point in Spain (Gades, which is modern-day Cadiz), his first attempt proved too difficult due to weather and distance, and he was forced to turn back. On his second attempt, Eudoxus vanished and his fate has never been discovered, though it is generally assumed he and his crew foundered during the attempt to complete the ambitious journey.
5 ANCIENT MARINERS
PYTHEAS OF MASSALIA
CIRCA 350-285 BCE
A Greek explorer who became the first person to describe the Midnight Sun in northern Europe.
CIRCA 360-300 BCE
Nearchus provided details for the book Indica, describing India after Alexander the Great’s conquest.
EUDOXUS OF CYZICUS
A Greek navigator, he is the first recorded European to sail using the monsoon winds in Asia.
HANNO THE NAVIGATOR
Most famous for his exploration of the west African coast, he made it farther south than anyone before.
NINTH CENTURY CE
Credited with discovering Iceland, he used three ravens to help him find land — one of which led to Iceland.
THE ANTIKYTHERA MECHANISM
1ST CENTURY BCE
Built with up to 30 gears, this ahead-of-its-time device worked like a modern clock to predict the location and alignment of stars.
This device was used to measure angles — eg the angle between the horizon and the Sun — in order to establish a ship’s latitude.
13TH CENTURY CE
Used by Viking navigators on cloudy days to determine the location of the Sun thanks to the way it polarised/refracted light.
USE THE MOON
If the Moon rises before the Sun sets it is trailing the Sun and so the bright side will point approximately west.