Tuesday, 16 October 2012

Polynesian Navigators

This book was one of my main resources when I first wrote about Polynesian navigation on the now-defunct Multiply site. The information about the picture of the coconut sextant and description of how it was used came directly from this book. I was, and remain, absolutely fascinated by the navigational and exploration skills of the people we now know as Polynesian, and the tools they used. On Multiply this all became a three part blog plus the book review; what is posted here is severely edited, selected highlights.

In the above book Tom Davis tells of his childhood in Rarotonga, about his education in Aotearoa/New Zealand, and how he became the first Cook Islander to qualify as a doctor; how he then returned as a "Doctor to the Islands" (the title of his first book) in 1945; and how he became the first Cook Islander to attend Harvard University, arriving there in a typically Tom Davis way - by sailing his small yacht from New Zealand to the USA. He headed medical programmes in Alaska and the Himalayas, managed medical research for a US consulting firm, qualified as a space surgeon and had a leading role in developing the US space programme.

In 1971 he returned to the Cook Islands where he became involved in politics and was Prime Minister there from 1978 - 1987. He was awarded the Order of Merit of Germany in 1979 and knighted by the Queen of England in 1980. Sir Tom expresses his views clearly, and admits what he failed to achieve or wished he had done differently. His power of description, as in handling a ship in a storm, is tremendous. In later life he also wrote a couple of books (including the one pictured above, obviously), coached a Cook Islands boxing team, and built an ocean-going canoe/waka.

"A navigator," said Tom Davis (Pa Tuterangi Ariki), "is travelling in an upside-down bowl of the sky sitting on the sea. It is full of clues as to the direction and the maintenance of that direction. The (modern) compass has blinded most of us to their existence and how they may be used."

 Polynesian Navigating Tohunga often would use a a sextant (titiro etu) made from a coconut shell cut across at a slanting angle with a hole at the low end, and a notch at the top end, and a number of holes encircling it. These sat above a wavy line representing the ocean and underneath an arch of ten stars evenly spaced. The coconut shell was filled with seawater to the ring of the holes. Coconut oil was used to preserve the surface tension of the seawater and, (within reason), to prevent leakage from the ring of holes.

Tom Davis spent some time in working out just how one of these was actually used. It turned out that the gourd instrument performed as a "Star Latitude Sailing method to "run down" one's destination, which is the same as a Sun Latitude Sailing method. One did not need a chronometer, nor did one need a declination table because all star declinations are fixed... All one has to know is that a particular altitude of star obtained by the titiro etu put's one's canoe on the same east west track as one's destination. Keep the canoe on that track and one will run into one's destination" (Tom Davis).

So "what we have" (writes Sir Tom), "is an artificial horizon built into the instrument, just like a bubble sextant. Now peek through the eye hole to the object hole or notch higher up and on the other side of the instrument. Wiggle the instrument around until one sees the star in the object hole. Follow it by intermittent sightings as it ascends until it reaches it's highest point...

Now look at the status of the artificial horizon. In this example, both the the destination and the reference star are to the north. If the seawater of the artificial horizon is above that of the ring of holes directly under the object hole, the canoe has not yet reached a point directly east (or west as the case may be) and one must continue one's course. Alternatively, if the star is below the object hole when the sea water is in line with all the holes, we also have not reached the latitude of our destination.

When the star is in the object aperture and the water of the artificial horizon is in line with all the holes of the ring of holes, one has reached that point where the canoe can be aimed directly east (or west...) and the destination can be 'run down

Europeans are used to text and to drawings, such as those that are used in our own maps and navigation charts, thus most people influenced by European symbols and a pen-on-paper written tradition, would probably fail to recognise the object pictured as a navigation chart.

This particular navigation chart is a replica from the Marshall Islands. Cowrie shells represented the relative positions of islands, while curved and diagonal sticks showed swell and wave patterns. Today, these objects are mainly sold as tourist souvenirs, but these ancient navigation aids were once vital for island hopping between the one thousand and more islands that make up the Marshalls group. The charts were not carried on board, but were meant to be memorised. They were also used to record collective knowledge and were useful in training young navigators.

The origins of the peoples of the Pacific can be traced back to the landmass we now know as mainland Asia. The migrations of Polynesian peoples are particularly impressive considering that the islands that were settled by them are spread out over great distances. The Pacific Ocean covers nearly a half of the Earth's surface area. Within a few centuries between about 1500 and 900 BC, the Lapita culture spread 6000km further to the east from the Bismarck Archipelago, until it reached as far as Fiji, Tonga and Samoa. It is in this region that the distinctive Polynesian culture was developed.

Then from about 300 CE, this developing and restlessly moving Polynesian people spread out from Fiji, Tonga and Samoa to the Cook Islands, Tahiti, the Tuamotus and the Marquesas Islands. Sometime between 300 and 1200 CE the Polynesians then discovered and settled on Rapa Nui (Easter Island). This is supported by archaeological evidence as well as the introduction of flora and fauna consistent with the Polynesian culture and characteristic of the tropics to this subtropical island. Around 500 CE Hawai’i was settled by the Polynesians and around 800 - 1000 CE Polynesian people travelled to and settled in Aotearoa/New Zealand.

Polynesian double-hulled Waka: The addition of sails to Polynesian vessels gave more power and allowed them to travel faster and further than with paddles. Two hulls gave stability and seaworthiness. This sketch of a double-hulled vessel was made by Abel Tasman in his journal while at Tongatapu in 1643.

In fact Polynesian sailors could sail rings around the sailing ships of exploring captains, Tasman and Cook. Waka were just so much faster and more efficient. In Anne Salmond's "The Trial of The Cannibal Dog" she describes how waka guiding Cook's vessels had to keep slowing down so that Cook and crew wouldn't get left behind.  Ocean-going waka could be stocked with provisions, laden with cargo, and carry up to one hundred passengers: they were ships in their own right.

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