Star Navigation to Aotearoa.

David Lewis was among the first to investigate comprehensively the navigation skills of the Micronesians and Polynesians. During 1965 to 1969 Lewis crisscrossed the Pacific to gather and use solely Pacific methods of navigation. Initially without much experience of that culture, on his catamaran, Rehu Moana, a voyage from Tahiti to Aotearoa via Rarotonga was completed from September 24^th to December 13^th 1965.

On leaving Rarotonga the course that Lewis was followed was:

“in early November sail a little to the left of the setting sun, or, one hand span to the left of the setting sun, two-thirds of a hand span left of Venus. Before Venus set, the Pleiades rose astern, followed as the night wore on by Bellatrix, Procyon, Castor and Pollux in turn. Towards morning the Pointers and the Southern Cross were abeam to Port.”

The Polynesian course was to continue WSW sailing down the star path by night and the sun path in the daytime. The estimation of the direction using the extended arm and hand method was to head 16° left of the setting sun, 10° left of Venus with the Pleiades astern. Towards morning the Southerrn Cross rose 5° forward of the beam and Castor and Pollux were astern.  The rising sun stood 54° to the right of the stern. The sun bearings changes with the date and our latitude while the stars remained unaltered only rising four minutes earlier each night. An angle of 15°  was taken as the span between thumb and middle finger, with the fingers relaxed and the arm extended. The tip of the index finger at arms length measured 1°.

In European navigation terms assuming the voyage begins on November 1 and lasts for 30 days (or a little more), the setting sun bears 254° from Raiatea (17 south) on November 3 and 243° from just south of North Cape, NZ, (35° south) in early December. So the main bearing of the setting sun during the voyage will be 248°.  

The course from Raiatea-Rarotonga-North Cape is 240°, while that from Raiatea-Mangaia-southern South Island is 227 ° ; this is there is a margin of 13° between the northerly and southerly courses thsat would both reach New Zealand. The Bay of Plenty, where most of the migration canoes landed, bears 230 from Raiatea or Rarotonga.  The navigators could comfortably use a course 15 to the left of the setting sun (248° -15° =233°)

Across all the voyaging traditions and recent navigation investigative voyages there is a remarkable consistency of stars and planets to make landfall in Aotearoa from Tahiti:

 Antares, Canopus, Sirius, Orion’s Belt, Venus and the Milky Way.

The voyaging season was generally in late Spring and Summer when the sun is south of the equator. Navigators set a course of 233° by using one and a half hand widths south of the setting sun, and one fist width south of the setting Venus. It is fitting that the advise, reputedly of Kupe, for the Te Arawa canoe for sailing from Rarotonga to Aotearoa was to steer a little to the left of Venus in the month of February.