S

,e tatanga

Pleiades setting

Rigel Antares rising

Figure 11.2. The sky pictured as a giant house, in which the celestial meridian is the ridgepole, the horizon, the "roof-plate," and the diurnal circles, the vertical rafters, oka. Drawing by E.F. Milone.

,e tatanga

Pleiades setting

Rigel Antares rising

Figure 11.2. The sky pictured as a giant house, in which the celestial meridian is the ridgepole, the horizon, the "roof-plate," and the diurnal circles, the vertical rafters, oka. Drawing by E.F. Milone.

compass" (which had been passed down to him across generations since it was last used) and accurately achieved landfall after crossing more than 700 km of open ocean. There is an even longer successful voyage by a traditional navigator.

In the Caroline Islands, as elsewhere, the ancient traditions of navigation in the native manner are rapidly fading as charts and sextants replace the old conceptions. Still, Stephen Thomas (1987) was able to get training in the ancient practices. A teaching device similar to that used in the Gilbert Islands is still found. They lay out a circle of 32 rocks with a model canoe in the center. These mark the rising and setting points of 16 named stars. Their resemblance to some megalithic stone circles elsewhere in the world is striking, despite the difference in scale. These primary navigational stars were also important in giving names to the months, although there were also many months that took their names from other stars.

The process of Polynesian navigation has been described by David Lewis (1972/1975) after he had undertaken successful sailings with crews using traditional methods. He also took part in a navigation experiment involving a native craft piloted by a native navigator from Hawaii to Tahiti, a voyage of 5370 km. The voyage and the events and trials that led up to it have been discussed by Finney (1976b/1977/1979). The two-masted, twin-hulled, sailing craft was called the Hokule'a, and it was one of two ships constructed to test the ocean-faring capability of traditional water craft. With a fully loaded displacement of 11,400 kg, it was large enough to contain provisions for a lengthy voyage and the animals and plants needed to begin a new colony. The experiment demonstrated that such craft had a surprising ability for windward travel, permitting a great deal of control in the face of the predominant easterly trade winds on either side of the equator.4 This is critical for regular eastward travel, such as that from Hawaii, which lies about 5° west of Tahiti, to the island groups to the southeast. It also demonstrated convincingly that traditional navigational methods and craft could have been used to support migrations in the Pacific.5

The navigational techniques involved both astronomical and nonastronomical means. The native navigator, Pius Piailug, known also as Mau, used a combination of astronomical methods to determine latitude, including the observation of the altitude of Polaris north of the equator, and the direction of the risings and settings of key stars, from "pits" on the horizon, both north and south of the equator. The nonastronomical methods included the sighting of direction of islands of known bearing, and a kind of dead reckoning, whereby the rate of motion was gauged from the feel of the wind and waves on the boat and the craft's rocking and rolling motion through the water. In the daytime, use of the Sun could be supplemented by ocean swell angles. Once the navigational methods succeeded in getting a craft within tens of miles from land, the presence of birds signaled the proximity of the shore. The range can be determined to some extent by the type of bird seen:

(1) Black tern: 10-15 miles

(3) Otaha (frigate bird): 30 miles

(4) Eua'ao (brown booby), white booby: 40 miles

Clouds were also used as important markers, and changes in ocean currents were often discernible to a trained navigator at considerable distances from land. Ammarell (1999), writing from personal experience among the Bugis6 in the archipelagos of Indonesia, points out that the chop of colliding winds and local currents, the change in wavelength of the waves as the water depth decreases near shore, and debris from shore all provide additional markers.

The nonastronomical techniques were particularly important for reckoning E-W motion, because time and longitude are inextricably bound, and in the absence of a chronometer or other precise way of marking time, hour angles are not particularly helpful in determining longitude. However intrinsically difficult it may have been to determine the eastern or western progress, the bearing of the craft could have been determined with high precision: The Sun always rises somewhere on the eastern horizon, and the time of year governs the point on the horizon from which it rises at a given latitude on Earth, as we have discussed in earlier chapters (see, especially, §3.2.1). Moreover, stars on the celestial equator will always indicate the direction of true east as they rise. Dodd (1972, pp. 48-55) demonstrates how a sequence of fore-and-aft stars arising from horizon pits could have been used while sailing roughly east-west near the equator. The canoe's direction was aligned to both the rising and the setting pit at the same time rather than to particular stars marking the pits. The position of a pit may be determined

4 Finney (1976b/1977) indicates that Hokule'a's speed was at least 10km/h on a course of 70-75° off true wind, while sailing in moderate-to-strong head winds.

5 A period of optimum voyaging conditions may have prevailed between 450 and ~1200 a.d., when mild trade winds and possibly stronger, more frequent westerlies, may have occurred; strong trade winds and increased storms are hypothesized to have occurred during the Little Ice Age (15th-17th centuries), making long voyages hazardous (see citations in Finney 1977).

6 A people of the island of Sulawesi, and found widely in the region, including the Indonesian archipelago.

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