Before 1400 many people traveled on open oceans:
Polynesians, Micronesians, Persians, Arabs, inhabitants of Indian
Ocean islands such as the Maldives.
But all traditional ocean sailing relied upon regular winds and
currents or an easy-to-follow continental shelf. |
Winds and Currents
- Before 1400 traditional voyagers on the open ocean relied upon
highly predictable seasonal winds and currents that came to be
called "trade winds" because when they blew, the traders sailed
into or out of harbors. In the Indian
Ocean, for example, north of the equator northeast winds
prevailed in the winter and south of the equator, the northwest
winds. During the rest of the year the winds blew steadily from
the south and west.
- Similar regular patterns occur in the Pacific
Ocean as the Hokulea
has demonstrated the autumn of 1999 by sailing all the way
from Hawaii to Rapa Nui (Easter Island.).
- To supplement these predictable regional and seasonal
patterns, all oceangoing travelers following trade winds and
currents developed elaborate native star
charts for directions, since the stars were their most
dependable "landmarks" on open oceans.
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Continental Shelf
- is the very high ocean floor just near land. Sometimes this
high ocean floor extends for hundreds of miles into the ocean.
Taking the sounding depths of the ocean floor, sailors could
navigate considerable distances, even without absolutely regular
winds and currents. Most of the navigation in Northern
Europe and the South China Sea for
centuries followed the continental shelf. Continental shelf
sailors usually also had a traditional star map--but often these
were very simple--consisting of a few stars and
constellations--and were far less elaborate than those of high
seas navigators such as the Polynesians. The Vikings
had managed to navigate to Greenland by hugging the high
continental shelf. and using the midnight
sun.
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