3.9 Evolution of the Sailing Strategy of Following Fast Warm Currents over Long Distances 57
central Pacific is important for appreciating its place in the Spice Islanders’ adoption
of the strategy of following fast currents. Their evolution of the double-outrigger
ultimately made possible their progression to transoceanic sailing. (We wish to
acknowledge the help given us by the late Ernie Tuck, ship hydrodynamicist,
personal communication, in clarifying the relevant ideas.)
Sixty thousand years ago bamboo rafts may have carried the first peoples of New
Guinea and some of the earliest ancestors of the aboriginal peoples of Australia
from Sundaland to Sahul via Halmahera. Twenty thousand years later bamboo rafts
may have carried the first settlers to the Spice Islands. Bamboo, which grows readily in Island Southeast Asia, is a remarkably useful material for raft construction.
It contributes weight (giving the raft stability), buoyancy (air chambers in its stems
make the raft unsinkable) and constructional flexibility, enabling the raft to ride relatively smoothly through rough ocean waters. Experiments conducted in Indonesia
by Alan Thorne [26] showed that a bamboo raft could be constructed in a few hours,
that it was “surprisingly easy to steer and control” and that it “moved freely along
at four or five knots”. Recent evidence that Homo erectus reached Flores by a series
of sea crossings, the longest of which was at least 20 km, suggests the possibility of
an astonishing antiquity for bamboo rafts in the region. Steve Webb suggests their
antiquity may be as great as 750,000 years [27].
Salt water rafts, sailing rafts (made from wood rather than bamboo) and reed
boats and reed rafts existed in prehistoric Polynesia and down to modern times.
Where little wood was available, as in Easter Island and in the Chatham Islands
east of New Zealand, reed rafts were the only choice. The Chatham Island reed
rafts were beautifully crafted and sophisticated, using the buoyancy of sea-kelp to
improve flotation. They are said to have been able to carry 60 persons between
islands. A long, varied and extensive use of rafts throughout Polynesia suggests a
cultural familiarity and expertise that could perhaps reach back to their ancestors’
arrival in the Spice Islands on rafts 40,000 years before.
In following a fast current, a bamboo sailing raft would have distinct advantages.
With its whole area in contact with the water, the propulsive power of the current
would be optimally transferred to the raft. However, it would require a large area
of sail to be able to make any headway against a contrary current because its drag
coefficient would be so high. In the Indian Ocean where the Equatorial Current
forms a continuous loop with the Indian Counter Current, a straightforward return
journey from the Spice Islands to Africa was possible. A sailing raft would have
been able to handle the Cinnamon Route. In the West Pacific Warm Pool a raft could
have followed the Kuro Shio Current from the Spice Islands through Micronesia to
Japan, but the return journey to the Spice Islands would have been difficult. In order
to return to the Spice Islands the raft would have to sail south just beyond the reach
of the current, perhaps travelling outside its western edge past the islands of Oshima
and Okinawa and down the western coast of the Philippines. It would probably have
to make several stops to wait for favourable wind conditions and all the way the
wind power of the sails would have to fight the drag of the raft.
For a return journey which is only supported one way by a strong current, a
double-masted Halmaherian double-outrigger would be a far better choice. Having
central Pacific is important for appreciating its place in the Spice Islanders’ adoption
of the strategy of following fast currents. Their evolution of the double-outrigger
ultimately made possible their progression to transoceanic sailing. (We wish to
acknowledge the help given us by the late Ernie Tuck, ship hydrodynamicist,
personal communication, in clarifying the relevant ideas.)
Sixty thousand years ago bamboo rafts may have carried the first peoples of New
Guinea and some of the earliest ancestors of the aboriginal peoples of Australia
from Sundaland to Sahul via Halmahera. Twenty thousand years later bamboo rafts
may have carried the first settlers to the Spice Islands. Bamboo, which grows readily in Island Southeast Asia, is a remarkably useful material for raft construction.
It contributes weight (giving the raft stability), buoyancy (air chambers in its stems
make the raft unsinkable) and constructional flexibility, enabling the raft to ride relatively smoothly through rough ocean waters. Experiments conducted in Indonesia
by Alan Thorne [26] showed that a bamboo raft could be constructed in a few hours,
that it was “surprisingly easy to steer and control” and that it “moved freely along
at four or five knots”. Recent evidence that Homo erectus reached Flores by a series
of sea crossings, the longest of which was at least 20 km, suggests the possibility of
an astonishing antiquity for bamboo rafts in the region. Steve Webb suggests their
antiquity may be as great as 750,000 years [27].
Salt water rafts, sailing rafts (made from wood rather than bamboo) and reed
boats and reed rafts existed in prehistoric Polynesia and down to modern times.
Where little wood was available, as in Easter Island and in the Chatham Islands
east of New Zealand, reed rafts were the only choice. The Chatham Island reed
rafts were beautifully crafted and sophisticated, using the buoyancy of sea-kelp to
improve flotation. They are said to have been able to carry 60 persons between
islands. A long, varied and extensive use of rafts throughout Polynesia suggests a
cultural familiarity and expertise that could perhaps reach back to their ancestors’
arrival in the Spice Islands on rafts 40,000 years before.
In following a fast current, a bamboo sailing raft would have distinct advantages.
With its whole area in contact with the water, the propulsive power of the current
would be optimally transferred to the raft. However, it would require a large area
of sail to be able to make any headway against a contrary current because its drag
coefficient would be so high. In the Indian Ocean where the Equatorial Current
forms a continuous loop with the Indian Counter Current, a straightforward return
journey from the Spice Islands to Africa was possible. A sailing raft would have
been able to handle the Cinnamon Route. In the West Pacific Warm Pool a raft could
have followed the Kuro Shio Current from the Spice Islands through Micronesia to
Japan, but the return journey to the Spice Islands would have been difficult. In order
to return to the Spice Islands the raft would have to sail south just beyond the reach
of the current, perhaps travelling outside its western edge past the islands of Oshima
and Okinawa and down the western coast of the Philippines. It would probably have
to make several stops to wait for favourable wind conditions and all the way the
wind power of the sails would have to fight the drag of the raft.
For a return journey which is only supported one way by a strong current, a
double-masted Halmaherian double-outrigger would be a far better choice. Having