Pacific navigators relied on the light from celestial bodies to chart courses, sometimes across thousands of miles of open ocean. They created star compasses to aid in orienting themselves while at sea. One such navigator was Pius “Mau” Piailug, from the tiny island of Satawal in Micronesia. In 1976, Mau used the traditional navigation method he had inherited to sail the newly-built voyaging canoe Hōkūle‘a from Hawai‘i to Tahiti and back. This voyage re-awakened pride in indigenous peoples throughout the Pacific because it proved to the world that Polynesians intentionally settled the most isolated island group on the planet, Hawai‘i, through celestial navigation.
Mau taught a young Hawaiian boy by the name of Nainoa Thompson the way of traditional Pacific navigation. Thompson merged traditional knowledge imparted by Mau with modern sciences. Thompson divided his compass evenly into 32 houses, each measuring 11.25 degrees. The navigator is always at the center of the compass; as the navigator and his ship moves, so does the compass.
Using this star compass, Pacific Voyaging Society (PVS) navigators apply the principles taught to them by Piailug and Thompson to find their way underneath any sky in
How It Works
At sea, the navigator mentally divides the horizon surrounding him or her into 32 equidistant sections, known as houses. Traditional Pacific navigators observed that celestial bodies rise and set in specific houses. From our perspective here on earth, stars that rise in a northeast (Ko‘olau) house will always set in their corresponding northwest (Ho‘olua) house; the same is true for stars that rise in the southeast (Malanai) and set in the southwest (Kona). The star Arcturus, which Hawaiians called Hōkūle‘a, always rises in the house of ‘Āina Ko‘olau and sets in the house of ‘Āina Ho‘olua. Stars never cross the East-to-West line that separates the compass into North and South.
Notches carved into the canoe itself, at 11.25 degrees apart as measured from a fixed location acting as the center of the compass, allow a navigator to stand at the center and accurately locate the boundaries of each house. From there, navigators can identify constellations and follow the arc of a rising star across the night sky to determine the direction in which they are sailing.
At a given latitude, only certain stars will pass through the zenith (an imaginary point in the sky directly overhead the navigator). The brightest of these stars is always referred to as the zenith star of that latitude. The zenith star of Hawai‘i’s latitude (19 degrees N) is Hōkūle‘a, hence the name of the canoe. If the navigator knows the zenith stars of different latitudes, he can tell what latitude he is at by observing what star passes directly overhead at night.
If there are no stars visible, skilled navigators can observe the directions of winds and waves to stay on course. Swells and prevailing winds, unlike stars, travel north and south as well, from one house on the horizon to the direct opposite house, passing under the canoe.