Skip to comments.Floating A Big Idea: Ancient Use Of Rafts To Transport Goods Demonstrated
Posted on 03/22/2008 11:08:17 AM PDT by blam
Floating A Big Idea: Ancient Use Of Rafts To Transport Goods Demonstrated
MIT students built a small-scale replica of an ancient oceangoing sailing raft to study its seaworthiness and handling. (Credit: Donna Coveney/MIT)
ScienceDaily (Mar. 22, 2008) Oceangoing sailing rafts plied the waters of the equatorial Pacific long before Europeans arrived in the Americas, and carried tradegoods for thousands of miles all the way from modern-day Chile to western Mexico, according to new findings by MIT researchers in the Department of Materials Science and Engineering.
Details of how the ancient trading system worked more than 1,000 years ago were reconstructed largely through the efforts of former MIT undergraduate student Leslie Dewan, working with Professor of Archeology and Ancient Technology Dorothy Hosler, of the Center for Materials Research in Archaeology and Ethnology (CMRAE).
The new work supports earlier evidence documented by Hosler that the two great centers of pre-European civilization in the Americas-the Andes region and Mesoamerica-had been in contact with each other and had longstanding trading relationships. That conclusion was based on an analysis of very similar metalworking technology used in the two regions for items such as silver and copper tiaras, bands, bells and tweezers, as well as evidence of trade in highly prized spondylus-shell beads.
Early Spanish, Portuguese and Dutch accounts of the Andean civilization include descriptions and even drawings of the large oceangoing rafts, but provided little information about their routes or the nature of the goods they carried.
In order to gain a better understanding of the rafts and their possible uses, Dewan and other students in Hosler's class built a small-scale replica of one of the rafts to study its seaworthiness and handling, and they tested it in the Charles River in 2004. Later, Dewan did a detailed computer analysis of the size, weight and cargo capacity of the rafts to arrive at a better understanding of their use for trade along the Pacific coast.
"It's a nontrivial engineering problem to get one of these to work properly," explained Dewan, who graduated last year with a double major in nuclear engineering and mechanical engineering. Although the early sketches give a general sense of the construction, it took careful study with a computerized engineering design program to work out details of dimensions, materials, sail size and configuration, and the arrangement of centerboards. These boards were used in place of a keel to prevent the craft from being blown to the side, and also provided a steering mechanism by selectively raising and lowering different boards from among two rows of them arranged on each side of the craft.
Although much of the raft design may have seemed familiar to the Europeans, some details were unique, such as masts made from flexible wood so that they could be curved downward to adjust the sails to the strength of the wind, the centerboards used as a steering mechanism, and the use of balsa wood, which is indigenous to Ecuador.
Dewan also analyzed the materials used for the construction, including the lightweight balsa wood used for the hull. Besides having to study the aerodynamics and hydrodynamics of the craft and the properties of the wood, cloth and rope used for the rafts and their rigging, she also ended up delving into some biology. It turns out that one crucial question in determining the longevity of such rafts had to do with shipworms-how quickly and under what conditions would they devour the rafts? And were shipworms always present along that Pacific coast, or were they introduced by the European explorers?
Shipworms are molluscs that can be the width of a quarter and a yard long. "Because balsa wood is so soft, and doesn't have silicates in it like most wood, they are able to just devour it very quickly," Dewan said. "It turns into something like cottage cheese in a short time."
That may be why earlier attempts to replicate the ancient rafts had failed, Dewan said. After construction, those replicas were allowed to sit near shore for weeks before the test voyages. "That's where the shipworms live," Dewan said. "One way to avoid that is to minimize the amount of time spent in harbor."
Dewan and Hosler did a simulation of the amount of time it would take for shipworms to eat one of the rafts and concluded that with proper precautions, it would be possible to make two round-trip voyages from Peru to western Mexico before the raft would need replacing.
The voyages likely took six to eight weeks, and the trade winds only permit the voyages during certain seasons of the year, so the travelers probably stayed at their destination for six months to a year each trip, Dewan and Hosler concluded. That would have been enough time to transfer the detailed knowledge of specific metalworking techniques that Hosler had found in her earlier research.
While Hosler's earlier work had shown a strong likelihood that there had been contact between the Andean and Mexican civilizations, it took the details of this new engineering analysis to establish that maritime trade between the two regions could indeed have taken place using the balsa rafts. "We showed from an engineering standpoint that this trip was feasible," Dewan said. Her analysis showed that the ancient rafts likely had a cargo capacity of 10 to 30 tons-about the same capacity as the barges on the Erie canal that were once a mainstay of trade in the northeastern United States.
Hosler said the analysis is "the first paper of its kind" to use modern engineering analysis to determine design parameters and constraints of an ancient watercraft and thus prove the feasibility of a particular kind of ancient trade in the New World. And for Dewan, it was an exciting departure from her primary academic work. "I just loved working on this project," she said, "being able to apply the mechanical engineering principles I've learned to a project like this, that seems pretty far outside the scope" of her work in nuclear engineering.
The findings are being reported in the Spring 2008 issue of the Journal of Anthropological Research.
Adapted from materials provided by Massachusetts Institute of Technology, via EurekAlert!, a service of AAAS.
Thank you - Title should be
Univesity reinvents wheel.......
You beat me to it....Heyerdahl goes over 4K+ miles on a raft across the Pacific in the late 40’s...MIT goes out for a half hour ride in a river....big deal.
Interesting, although there are some serious anomalies if the two groups of civilizations were in constant contact.
For instance, while corn native to Mexico made it to Peru, I don’t believe potatoes, native to Peru, made it to Mexico.
Also, writing was common in Mexico and unknown in Peru.
In many other ways the two civilizations are as different from each other as any two on earth.
The history channel had a special on big ships that were as big as a football field 1,000’s of years ago.
Who writes this tripe?
· Mirabilis · Texas AM Anthropology News · Yahoo Anthro & Archaeo ·
· History or Science & Nature Podcasts · Excerpt, or Link only? · cgk's list of ping lists ·
How do they trot this crap out, anyway?
Are they going to float the idea that the Earth is not the center of the Solar System next?
So, once again, modern elitists have discovered that people thousands of years ago were actually intelligent and had a talent for engineering.
Sailors sail, archaeologists don’t. End of story.
You beat me to it. MIT students needed computer programs to design their rafts while the originals were probably slapped together in a couple days with what was on hand.
Equatorial waters are fairly calm and storm free, so rafts may have worked.
In my library is the book Kon Tiki that solved these problems years ago. I feel guilty because I borrowed the book from my uncle and never returned it.
Yes, but think of all the self-esteem & "knowledge" that was generated! /sarcasm
LOL! I read Kon-Tiki in hs, and that’s the first thing I thought of when I got the ping.
I read it in HS and OK.
Then, I read ot again as an adult. Thor was a Commando in WWII - as an adult, it was a story of a bunch kick-ass Commndo types taking on the ocean in a lttle raft.
And the ham part? They used an old WWII “Radio Swan” (spy) rig, too cool
I didn’t realize how much education I missed by going to High School...
Hmmmmm....I guess it would be a good idea for me to read it again, too (with all the MO flooding), there are a bunch of books I need to re-read. I thought he was a really good-looking man, at the time, and the story was just fascinating.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.