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[gfish]

On the application of the Polynesian etak navigation system to terrestrial bicycle travel

Abstract
The Polynesian etak, or reference island, is a hard concept for those not raised to it. As a test of his understanding, the author used the principles during the second stage of a 210 mile bike ride. It was found that doing so, while helping him internalize the system, was not a great help navigationally.


Introduction
The only direct measurements available to Polynesian navigators were headings as given by their star compass. Differing slightly for each culture, the horizon was divided into bearings defined by the point where certain stars rose or fell. Since that only happens once a night, each bearing was actually a chain of stars, each rising or setting at the same point in turn.

While it required the navigator to remember large amounts of data, this system can be quite accurate. However, knowing the bearing from every island to every other island isn't enough. Contrary currents and winds mean that it is never enough just to sail in the right direction. You need to know where along the path you are in case something goes wrong. A trained navigator could estimate daily travel fairly accurately, particularly in seas that he knew well. But over a journey of several days or weeks the errors would quickly add up. They needed a way to quantize this very qualitative data. Etak is the system that was developed, which only uses the only direct measurement they had available: star compass bearings.

Instead of focusing on the movement of the vehicle as it moves from island A to island B, a reference island (or etak) C is chosen. C would not be visible, but the bearings to it from A and B would be known. As the journey progresses, the bearing of C as seen from the vehicle will gradually change from the initial value, through the intermediate star positions, to the final bearing from B. The journey is conceptualized as the movement of this reference island, not of the vehicle itself.

The progression of the etak through the points of the star compass naturally divides the journey into discrete segments (also called etak). These are the quantized units needed for thinking about progress along the journey, and they also provide a framework for contingency actions in case of storm drift.

This is a difficult concept for people raised with a western concept of navigation. Etak is not a measurement system, it is a mnemonic for keeping track of current location are based on the estimated distance already traveled. It changes the equation from 'We traveled a normal day's distance the first day, but the second day was kind of slow, and the third day we barely moved at all' to 'The first day we finished one etak. The second day put us a bit over half of the next one, which we just finished on the third day.' It allows one to think about imprecise terms in precise quantities, though of course it is only as good the dead-reckoning skills of the person using it.

Methods
At the beginning of the second day of his journey, the author chose Mt. St. Helens as his etak reference point. This was chosen because it was well positioned between his origin (Centralia) and his destination (Portland), resulting in bearings of south-east to begin with and north-north-east at the finish. It was also hoped that, as a prominent and distinctive mountain, it would regularly be visible from the route to provide feedback. This did not turn out to be the case, but the author does not feel that integrity of the experiment was compromised.

Bearings were expressed using purely western terminology throughout the experiment. This was done because, being a daytime experiment, star positions were not available for reference, and also because the author has little practical astronomical experience.

For convenience, the etak segments were defined by each small town the route passed through. The author would look at the bearing to Mt. St. Helens for the beginning and end of that segment, then try to visualize the movement during the ride.

Results
Overall, the author did find etak to be a useful way to visualize progress along his journey. However, several things greatly reduced its usefulness for bicycle transportation.

Most importantly, it is hard to look more than 90 degree away from straight ahead while riding a bicycle. For something as fuzzy as etak, particularly if it were practiced using real star bearings, this is a major problem. This was a large reason why the experiment received less of the author's attention in the later half of the day, though deep exhaustion might have also been a factor.

Another important difference between a bicycle and a Polynesian voyaging canoe is that the immediate bearing of a bicycle changes frequently as it follows the road. This greatly complicates visualizing the orientation of anything relative to the vehicle. The author attempted to use the angle of the sun, but that is a dead-reckoning skill that he has yet to develop fully. For much of the time he was unsure of the direction of north more precise than 45 degrees. He was unwilling to pull out his magnetic compass and check more than a few times out of embarrassment.

However, the author did find that the experiment greatly increased his understanding of the etak system. He feels that he has made the cognitive leap to being able to view world in those terms, and he recommends similar experiments to anyone interested in the subject.

Conclusion
Etak is not well suited to navigation on county highways while riding a bicycle. Followup experiments in solar direction finding are called for.

References
Lewis, David. 1972, 1994. We, the Navigators: The Ancient Art of Landfinding in the Pacific

Comments

[stolen-tea.livejournal.com]

Ahhh, so it's not a substitute for guessing, but instead a way to systematize the guesses so that you're more likely to be correct?