How exactly were the ancient Polynesians, including those who discovered New Zealand, able to navigate across the truly vast expanses of the Pacific Ocean?
How were they able to discover the numerous islands that were mere dots in the vastness of the Pacific?
How were they able to find where they were going, and more importantly, if need be, how were they able to find their way home?
In a previous blog post, “Who Discovered New Zealand?”, I discussed the discovery and colonization of Polynesia including New Zealand. To reiterate, the exploration and colonization of Polynesia didn’t happen by chance or luck. Rather, it was the result of voyages of deliberate exploration over a long period of time.
The great years of Polynesian navigation and exploration, the time during which most of the islands in the Pacific were discovered and colonized, were from around 1000 BC to 1300 AD, after which time, for various reasons, the great age of Polynesian exploration ended.
During these thousands of years in the heyday of Polynesian navigation, both the craft used and the techniques of navigation presumably evolved. The Polynesians didn’t keep any written records of their techniques, and certainly there are no records of all the failures, of all the times ships became lost or foundered at sea, the crews drowning or slowly starving to death. But there is no question that the ancient Polynesians achieved a level of skill in sailing and navigation long before much of the Western World, at a time when European ocean-going voyaging was still in its infancy. Also, it is remarkable that the ancient Polynesians accomplished all this without the benefit of any navigational aids including such simple instruments as the compass or sextant.
Unfortunately, the early Europeans in the Pacific were not very interested in Polynesian navigation, and much of the knowledge of how exactly the ancient Polynesians navigated is lost. What is known is pieced together from various sources: word of mouth from various islanders, reports from Europeans when they first encountered Polynesians and did record things, and from techniques used in relatively recent times by islanders to travel and trade between relatively close islands. Also, in the late 20th Century, an interest in Polynesian navigation was rekindled and a number of experimental voyages were undertaken using re-constructed Polynesian boats and ancient navigation methods. These voyages confirmed that deliberate, long ocean voyages were indeed possible, and validated the Polynesian methods of navigation.
So how did they do it?
Polynesian navigation relied on a working knowledge and observation of stars and other celestial bodies, a knowledge of prevailing winds and their seasonal variations, a knowledge of swells and currents and knowledge of a whole list of more subtle observations—many of which most of us would not be aware of— such as cloud patterns, ocean and sky colors, and the migration patterns and habits of birds and sea life.
The embodiment of all this knowledge was the Polynesian navigator, who had been trained for years in his craft, much of the knowledge imparted to him being held secret by guilds on the islands. None of the knowledge was written down; everything was memorized by the navigator. Indeed, his whole body was one moving, breathing, calculating navigational machine taking in a variety of sensory input and observations to constantly determine course, direction and location.
Direction of Travel
Polynesian voyaging craft were large double-hulled sailing canoes. They could not be paddled any significant distance, hence, much depending on wind direction, and under optimal conditions, they could be sailed 150-250 km (100-150 miles) per day. Journeys of exploration were preferably made in an upwind direction. In this way, after beating into the wind for days or weeks, if no land was found, one could be assured of being able to turn around and relatively easily sail back home downwind.
Sailing across the wind was the next most desirable direction of sail, and finally sailing directly downwind was the most dangerous, since getting back to one’s starting point may prove difficult or impossible.
Islands in the Pacific were generally felt to have been discovered not in order of proximity, but rather in ease of which they could be reached or found by using prevailing winds, according to the above methods.
Similarly, when sailing to a known location, the navigator would purposely sail above his destination—to assure he didn’t miss it—and then make his way downwind until he hit it.
Dividing the Journey Into Segments
For journeys that were repeated over and over such as for trade journeys between islands and for fishing voyages out of sight of land, the journey was often divided into segments. The navigator would sail to one location perhaps using a known star, and then upon sighting an island or atoll, begin the next leg of his journey using a different star and different set of observations. Or, based on prevailing winds, the navigator would know that he (navigators were always men) could sail so many days in one direction until the winds would change. Then the navigator would chose a different direction based on the new prevailing wind.
In this way, the journey would be divided into segments, often using or primarily relying on different navigational aids for different segments of the journey.
Steering by the Stars
Polynesian navigators used the stars to steer by.
In simplest terms, if you remain at the same latitude, a given star will rise (towards the east) at the same exact spot every day, and set (towards the west) at the same exact spot every day. Timewise, each day the star will rise slightly (4 minutes) earlier. For example, if you see a star rising at close to dusk every day, eventually at dusk, you will find your star to be already up in the sky when it becomes dark enough to see stars. Your star will still be rising and setting at the same exact locations but just at different times, and because of its movement, its rising and setting may not be visible, i.e., it will already be up or down, or eventually may not be visible at all because it will up during the daylight hours.
As the seasons progress, different stars will become visible. They will be seen to be rising and setting in the night sky, again if you stay at the same latitude rising and setting at the same spots every day. If you travel north or south, however, your familiar stars will rise and set slightly north or south or where they were before. Eventually some of your stars may disappear entirely and whole new groups of stars will show up. Again, for example, if you cross over the equator from north to south, Polaris, the North Star, will no longer be visible and a whole new group of stars including the Southern Cross will appear to the south.
These are the basic principles involved in navigating by the stars. Ancient Polynesian navigators knew the direction or location of the rising and setting of hundreds of stars, and which new stars would rise and set as the year progress, and how the orientation of the stars would change as one travelled north or south. This formed the basis of what on some islands was called a star compass.
Whereas a magnetic compass has numerical directions, a star compass has a star, or rather a series of stars, in any given direction. Another major difference is that a magnetic compass is a physical object, whereas the star compass was carried entirely in the Polynesian navigator’s head, having memorized hundreds of stars and their patterns of rising and setting.
So, if all went as planned on a voyage, you could simply steer toward the appropriate rising star. When that star became too high in the sky to be useful, you—as the navigator—knew which star would rise behind it and could hence be steered toward. Or if you were sailing in a more westerly direction, you could use the setting of stars in the same manner.
But what if the sky was cloudy in the direction you were travelling. That’s the elegance of the star compass. Again, as the navigator, you would know which stars would be rising and falling in every direction, and you could steer by keeping a certain star directly behind you, or directly abeam.
Essentially, the entire sailing craft could be thought of as a giant compass. If you were sailing in the proper direction, you should see a whole circular array of stars correctly displayed in all directions surrounding the craft.
During daylight hours, the location of the rising and setting of the sun and its predictable arc across the sky could be used for navigation.
The Polynesian navigator would also take into account the effect of currents and swells on the craft’s direction of travel. If a strong swell was pushing the craft sideways, he might have to modify his star compass direction to adjust for this.
The winds in the Pacific are relatively predictable; they vary according to latitude and tend to blow in certain directions during certain times of the year, often for months at a time. Polynesian voyages timed their voyages to take advantage of this. At other times of the year, winds that generally blew in one direction could be predicted to change direction for a period of time.
Similar to the star compass described above, many ancient Polynesian navigators had compasses of wind direction, again, in their minds. Each wind had a name and its direction. They would know which winds from which directions could be expected at different latitudes at different times of the year.
Swells are caused by steady winds acting over long distances. They are long-lasting and persistent. Waves, by comparison, are caused by local conditions and are short-lived. The same prevailing winds discussed above lead to long-lasting swells. A skilled navigator can see and feel the direction the swell is coming from. In the absence of stars, or in conjunction with them, the navigator could keep the craft on course by keeping the canoe at the same angle to the swells. Hence, he could assume he was travelling in the same, consistent direction. On the more recent 20th century voyages described above, the skilled navigators were able to detect changes in direction of the craft based on swell direction even when below decks and out of sight of the ocean.
When swells strike land, they bounce back. A reflection wave, also called a bounce-back wave, can be detected up to 50 km away from small islands, and up to 300 km away from such a large landmass as New Zealand. Also, when swells strike an island, they curve around it, creating a distorted swell pattern that could be read by an experienced navigator.
On some Polynesian islands, stick charts were made to teach both the locations of islands and the expected change in currents and swells caused by the islands.
Knowledge of cloud types and their patterns could also be used by the navigator to determine not only the weather but also proximity to land masses. Certain types of clouds form above islands and can be seen great distances away up to 100 km away. Also, when a cloud is above an island, the underside of the cloud will often be of a different color reflecting the terrain of the island.
In navigation, dead reckoning refers to the process of determining one’s current position by calculating how fast and in what direction(s) one has travelled from a known starting position. It essentially involves attempting to answer the question: “Where are we now?”
Whereas traditional European navigators would keep a chart and record their estimated speeds and directions, Polynesian navigators would keep all this in their heads. They would keep a running total of all the subtle changes in speed and direction, of how the swells would draw the craft one way or the other, and putting all this together would have a sense of where they were.
Many more seabirds existed in past times than do now. It is speculated that huge flocks of seabirds surrounded many islands and could be seen from great distances away.
Many seabirds also fly out to sea in the morning and return at dusk. Some, such as the frigate birds, fly up to 100 km out to sea. By following birds homeward, a navigator could expect to eventually make landfall, or know that land was near.
Migrating birds also follow predictable patterns in the Pacific some travelling many thousands of kilometers. For example, certain species of cuckoo summer in New Zealand and then fly north to Melanesia and Polynesia for the winter. Polynesian navigators cold take advantage or follow these known migration routes.
Similar to birds, some marine animals such as whales, which were far more numerous in past times, also migrate travelling in slow-moving pods. Whales tend to calve along the shores of islands; hence, this could be used as another navigation aid.
Finally, a whole host of other subtler findings could indicate a nearness to land, including driftwood and other debris in the water, and even the smell of land.
Howe, K. (2006). Vaka Moana Voyages of the Ancestors. Auckland, New Zealand: David Bateman Ltd.
Finney, B. (1976). Pacific Navigation and Voyaging. Wellington, New Zealand: The Polynesian Society Incorporated.
Best, E. (1975). Polynesian Voyagers. Wellington, New Zealand: A.R. Shearer.