Closing the Triangle: A Quest for Rapa Nui
Polynesian Voyaging Society
Sailing Strategy / Leg 3. Mangareva to Rapa Nui (Sept.-Oct. 1999)
Hokule'a will leave for Mangareva with the first favorable winds in mid-September. It will have to gain 1533 minutes of longitude, or between about 1200 to 1450 miles to the east, to reach Rapa Nui. Sailing distance may be much greater (four or five times greater) if the canoe has to tack against easterlies. It will sail toward Rapa Nui whenever wind shifts allow it to do so. About 300 miles W of Rapa Nui (based on the navigators' estimate of distance traveled), the crew will begin a zigzag search pattern between 25° S and 29° S, looking for Rapa Nui (27° 09' S). Captain: Nainoa Thompson / Navigation Team.
Islands
Mangareva: 23° 10' S, 135° 00' W
Oeno Atoll (23° 56' S, 130° 44' W), about 230 miles E by S of Mangareva
Pitcairn: 25° 04' S, 130° 06' W; highest point: 1000 feet; 80 miles SE by S of Oeno
Henderson Island: 24° 22' S, l28° l9' W, 103 miles ENE of Pitcairn; highest point: 101 feet.
Ducie Atoll (Island) (24° 40' S., 124° 47' W); 195 miles ESE of Henderson
Rapa Nui: 27° 09' S, 109° 27' W; highest point: Terevaka, 1674 ft.
Sala-y-Gomez: a small reef, 230 feet long at high tide; 260 miles to the northeast of Rapa Nui. Birds nesting on this reef may be a clue that the canoe has gone past Rapa Nui in its search.
Rapa Nui is within a weather zone called the Southern Subtropical Divergence Zone (25° - 30° S): This area of high pressure, which produces the Southeast Trade winds, has light, variable winds and mainly clear skies. In September and October, around Rapa Nui, the wind are easterly (from NE to SE) 60% of the time, averaging 12 knots. Late winter and early spring cold fronts from storms to the south may bring wind shifts and westerlies. Currents in this zone are weak and variable, generally east-flowing at 0.1 to 0.5 knots.
Segment 1-Last Known Landfall
From Mangareva, Hokule'a will sail towards Oeno, Pitcairn, and Henderson, searching for them between 23° S and 27° S, using land-based seabirds as guides. Pitcairn, the highest island (1000 ft.), is 290 miles from Mangareva. These three islands, or Ducie Atoll farther east, will give the navigators a final position and bearing toward Rapa Nui.
Segment 2- Getting East
From the last sighting of land, Hokule'a will continue east into an empty ocean towards Rapa Nui, tacking against the prevailing easterly winds between 23° S and 31° S and taking advantage of any wind shifts to sail directly toward the island.
Segment 3-The Search for Rapa Nui
When Hokule'a is about 300 miles west of Rapa Nui , the navigators will begin a series of close tacks between 25° S and 29° S to search for the island; they will have to pass within about 30 miles of the island in daylight to see it from the canoe.
Totals for the Leg 3
Total Straight-Line Distance from Mangareva to Rapa Nui: 1430
Total Sailing Days: There will be 30-35 days time limit placed on the quest for Rapa Nui. Should the navigators not find the island within that time limit, they will be assisted by students to find the island.