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Thursday, May 29, 2008

Balsa Rafts in Precolumbian Trade Routes


An article in Science Daily a couple months back reported on the results of a fascinating study conducted at MIT's Department of Materials Science and Engineering into the feasibility of coastwise navigation between the two great civilizations of the precolumbian Americas.

Archaeologists have theorized about trade between societies in mesoamerica and the Andes based on similarities of metalworking technology between the two regions, as well as the presence of beads made from shells indigenous to only one of the areas that showed up in the other. Furthermore, they had descriptions and illustrations by early Spanish, Portuguese and Dutch travelers to the area describing oceangoing sailing rafts. But those two items are a long way from establishing that these rafts were capable of making the multi-thousand mile voyages that would have made such trade possible by means other than overland.

Researchers built a small-scale raft approximating what is known of the local technology and tested it successfully on the Charles River, then used performance data from that test and plugged it into engineering analysis (aero- and hydrodynamics, etc.) to establish whether full-size rafts were capable of making the trip. The study showed that they could. The rafts were steered with two rows of daggerboards, selectively deployed and retracted to alter the rafts' center of lateral resistance fore or aft. (The SD article calls them centerboards, but I think that must be wrong, due probably to the reporter's unfamiliarity with the terminology. Daggerboards, of course, are deployed and retracted vertically; centerboards are hinged at the top.) Unfortunately, the article doesn't describe the sailing rig, but does state that it used a flexible mast to alter the shape of the sail and, presumably, the fore-and-aft position of the center of effort.

The research also looked into the longevity of the Ecuadoran balsa logs. Teredos (shipworms) eat balsa far faster than they eat most other shipbuilding woods, but it was found that, by traveling in the ocean proper and keeping the raft out of shallow water where the worms are most active, rafts could have survived two round trips of six to eight weeks each. Because they relied on seasonal weather patterns (presumably sailing only downwind on seasonal trade winds), only one or two voyages could be made per year by a single raft and its crew. It's not explained how the rafts were kept safe from teredos during the time between voyages.

The paper was published in the Spring 2008 issue of the Journal of Anthropological Research. The photo shows the MIT test raft. Photo Credit: Donna Coveney/MIT.

Wednesday, May 28, 2008

My Swim

I took a canoe day trip last spring that ended in a swim -- not an epic one, but the biggest that I've experienced, and the first for my son.

I manned the stern of my Adirondack St. Regis, a 17-foot Kevlar cruiser; my son Max, then 10, manned the bow. Friend Tim was in the stern of his canoe, an Old Town Penobscot 16, with his son, Paul, also 10, in bow. The previous year, this same team had done a 6-day trip on the St. Croix River, between Maine and New Brunswick. This time, we were on the St. George River in midcoast Maine. It was our first trip of the year -- kind of a warmup for a weeklong trip on the Allagash planned for later in the year.

We put in at Seventrees Pond in Union, and the first nine tenths of the trip was flatwater: first the pond, then the river. Several hundred yards above the planned takeout at Payson Park in Warren, the river goes over a steep shelf, which we portaged. Thereafter, it was a very bony Class II. Lots of pushing against the bottom, half getting out of the boat and scooting along with one leg still in the boat, banging rocks. Although my St. Regis is a nice Kevlar boat, it isn't really made for this kind of work, but I long ago got over the pain of scratches and dings.

At a point where there was more than enough water to float the boat and plenty of current, we got sideways to a rock and in an instant we capsized upstream. I think I could blame Max for leaning the wrong way, but in fact it happened too quickly for me to really know. The boat then swung with the current and freed itself from the rock. Max was gasping and upset; somehow he was downstream of the boat, and I told him to get upstream of it, then reminded him of the "noses and toes" approach to swimming in current (keep the nose and the toes facing up, with feet pointing downstream) and he took the position. (Max and Paul had practiced this on the St. Croix and had much fun doing it.) I grabbed the boat and tried to maneuver it, but soon the current became too strong, too fast, and I had to let go of it and my paddle and just watch out for myself.

This was Max's first capsize; he was scared and shouting frequently but following the drill. Somehow, he quickly ended up on the opposite side of the river and there was no way that I could assist him in any way -- the strong current was dragging me, too, over shallow rocks and through holes down my side of the river. I was terribly scared for Max, but all I could do was keep my eye on him and confirm that he continued to head downriver with the current, apparently OK. If he had somehow gotten into real trouble, I could have done nothing. I did look back and note that Tim and Paul continued to follow us in their boat, which was some comfort.

There were a few painful bumps on the tailbone and several dunkings, but the noses-and-toes approach worked as advertised, and I used my feet to fend myself off the worst of the rocks. Even attempting to move to the bank was out of the question -- the current was just too strong to do anything but flow with it.

Eventually the current slackened, just in front of the planned takeout at Payson Park. Max came to rest on a little sandy island, and TIm and Paul quickly picked him up and deposited him on the bank. I found my footing and managed to walk to the bank. A woman who was with her children at the park took Max in hand, put him in her van and cranked up the heat and got him into dry clothing.

Tim and I grabbed my boat and carried it up the bank -- it was terribly bashed up; gunwales separated from the hull, dents, cracks all the way through the layup, one flotation chamber partially torn out. We found two of the three paddles -- the missing one was a lovely Shaw & Tenney model that I'd used only a couple times.

I was somewhat shaken up, and Max more than somewhat -- not enough, I'm glad to report, to interfere with the Allagash trip later that year. We were both wearing good PFDs (of course), and it's hard to imagine the stupidity of anyone who would put himself into that kind of situation without them -- it would have been immensely more difficult and scarier without flotation. It had been a drizzly day, so we were wearing raingear, which might have provided just a hint of thermal protection -- certainly not much. The water was a bit chilly, and we felt it, but wetsuits probably would have been overkill. Maybe I'm kidding himself here. Had this swim occurred away from civilization and been just a few hundred yards longer, hypothermia might have been a possibility.

It was a revelation how much damage a few hundred yards of shallow Class II could do to a Kevlar boat. I took it to a fiberglass pro whose repair estimate was about the same as the cost of a new boat. I kept looking, however, and found a fiberglass worker who does some work on the side. He did a nice job on the structural matters and added a minimum of additional weight -- I haven't weighed it, but my guess is less than 5 pounds.

The gelcoat is another story. Normally, gelcoat is sprayed into a polished female mold before the layup begins on the inside of the gelcoat, so a nice smooth surface results. In this case, the gelcoat was sprayed with a gun onto the boat's exterior laminate surface, leaving a very slightly pebbled finish. A racer couldn't tolerate it this surface texture, but it's fairly fine-grained and I doubt it will seriously affect the boat's efficiency. I did take the opportunity to change the boat's color, from green to white and it looks very nice if you don't get too close and notice the pebbles. For a total bill of $500, it was a reasonable way to rescue a pretty nice boat. I now realize it's not at all suited to whitewater, however, so I've got my eyes open for a plastic tub.

Sunday, May 18, 2008

Bull Boats


Bull boats were the coracles of the American Indians of the Great Plains, including the Lakota, Mandan and other Sioux, Cherokee, Assiniboine, Blackfoot, and others. Typically round and 8' or 9' in diameter, they were strictly women's craft among most of these people. Like the coracle, they were paddled by sitting (or standing, according to one account!) in the "bow" (i.e.,near the edge of whatever direction you were facing), placing the paddle in the water directly in front of you, and drawing the paddle toward you. Although there are some historical references to how fast they could be paddled, these must have been charitable or ignorant statements, for a boat like these could not possibly go fast by any objective measure, and from a design standpoint they really are about the slowest boats possible.

Named for their bison-hide covering, bull boats did not have the neat and elaborate framework of the coracle of the British isles. Rather, their frames were built with flexible sticks of varying shapes (often willow), and not all of them by any means straight. Not intended for long-time use, but intended to be portaged by women daily, they were lightly built, with "frame spacing" very large -- from photos I've seen, spaces between frames may have been nearly a foot in some instances.

Oddly, the hair was left on the hide, and the hide was attached with the hair side outward. This would have made a slow boat even slower (and heavier, when wet), but the hair probably fell off or wore off before long. The boats were removed from the water daily to dry, as they would have quickly rotted otherwise.

Most had an uppermost "gunwale" (at the top ends of the cross-frames) over which the covering was stretched, but in some (as in the illustration above), the cross-frames extended above the uppermost circumferential frame and the cover was attached to the ends of the cross-frames, giving these models somewhat of an inverted-umbrella look. Some Mandan people apparently used this method. Another charming feature is that the tail of the bison was left on, serving as a painter.

As women's craft, they were used for chores -- hauling firewood and such. With bison hide such a readily available staple of the Plains Indian economy, and with their simple frameworks, they were not considered highly valuable -- more "disposable," in fact -- and were probably abandoned readily and replaced with a new one when needed.

The 1833 illustration by Karl Bodmer shows Mandan bull boats.


Monday, May 12, 2008

Maine Jukung




The jukung is a dual-outrigger sailing canoe of Indonesia. Built dugout-style, most jukungs have a fascinating, decorative bifurcated stem extension that often resembles the wide-gaping mouth of some creature. They sport a variety of rigs, most having two booms set on a very short stub mast and some similarities to a lateen rig. One of their most distinctive features is the massive but graceful outrigger booms (i.e., the sticks that hold the floats), often with a kind of gull-wing curve to them. The curved ends are pegged and lashed to a center section that spans and is itself lashed to the hull.

I've been struggling through Outrigger Canoes of Bali and Madura, Indonesia (Bernice Pauahi Bishop Museum Special Publication) By Adrian Horridge (Bishop Museum Press, Honolulu, 1987), so was vaguely familiar with the type, when I was surprised to see one beside Route 1 in coastal Maine, sitting in front of a teak furniture importer/retailer in Newcastle. I stopped and spoke to the store's owner: he travels regularly to Bali and nearby islands on buying trips, and he picked up this canoe from a fisherman who was replacing it with a new one -- seems there was some rot in the hull which made it less than ideal as a fishing boat, but didn't impair its value as a roadside attraction.
In addition to fishing, jukungs are now used as "dive boats" in the tourist trade, bringing scuba divers out to attractive settings.

The photo was kindly placed in the public domain by a contributor to Wikipedia -- this one's in Indonesia, not Maine.

Oops

In my previous post, I drew a conclusion about the differences between the American Indians of the Northwest and the Northeast, stating that while those of the NW used their canoes in seasonal migrations, those of the NE did not.

I should have read further in the book that I was then citing,
The Canoe: A Living Tradition, for it states that the woodland Indians of the northeast did indeed use their bark canoes in seasonal migration. No details given, but I'll keep my eyes open and report more if I find any discussion.

Saturday, May 10, 2008

American Canoe Culture, East vs. West


In the chapter "Vessels of Life: Northwest Coast Dugouts" of The Canoe: A Living Tradition, Steven C. Brown noted that "the existence of sea-going canoes enabled the Aboriginal Northwest Coast peoples to become the masters of their worlds, living in a seasonal round of camp and village locations that were advantageous for the harvesting of varied and plentiful food resources."

This represented a fundamental difference from the canoe culture of the American northeast, beyond the very distinct craft that predominated in those two areas. For where the Northwest cultures (ranging from present-day Washington state to Alaska) relied upon their large dugouts for seasonal migration, the Northeast cultures did not rely on their smaller dugouts and bark canoes for the same purpose. Both cultures, of course, used their canoes as hunting tools (seeking different game), but the Indians of the northeast did not engage in coastwise migrations. Northeast seasonal migrations were, I believe, primarily movements from the coast to inland and back. Canoes would have been superfluous during the winter months spent inland, when all surface water is frozen.

The Indians of the Northwest, in addition, seem to have maintained a richer material culture, and their large dugouts were well-suited to carrying everything owned by a village. (Indeed, it is said that there were enough canoes in the region to carry every single person living there, plus virtually all of their portable goods.) Northeast Indians had less to carry on their migrations and could do it on their backs.

I suppose this just demonstrates what is a well-known distinction; that the Northwest Indians were a maritime culture, as distinct from the Northweast Indians, who were a woodland culture.

By the way, The Canoe: A Living Tradition is a very pretty book. Its content is uneven -- the level of detail and method of treatment varies from chapter to chapter, each of which was written by a different author -- but there's much interesting information here for a canoe history novice like myself, and lots of nice photos.

The photo above shows a 63' Haida canoe from the Queen Charlotte Islands off British Columbia and was built in 1878. It is from the website of the American Museum of Natural History and is described in detail here.

Tuesday, May 6, 2008

Dragon Boats Are Good for Your Health


Right. Or so says an article on Science Daily, adapted from a press release from McGill University. Dr. Catherine Sabiston of McGill's Department of Kinesiology and Physical Education conducted research on health and survival rates among female cancer survivors who are also dragon boat racers, and found a positive correlation compared to competitive canoe polers, canoe freestylists, and backcountry trippers.

No, really, according to the SD article, the study didn't compare the health outcomes of dragon boat racing to any other paddlesport (or to any other sport or lack thereof, for that matter), but interviewed the women about the psychological benefits they perceived from participating with other female cancer patients. Not surprisingly, the women were very positive about the experience, agreeing that it helped their attitude toward life and illness.

Wonderful. Sounds approximately as useful as my thesis for my Marine Affairs degree at the University of RI, in which I "analyzed" hundreds of photos in dozens of powerboating magazines to determine if they were placing extreme emphasis on the qualities of high speed (and implied, a disregard for high fuel consumption) over other qualities of the boating experience like comfort and quality. (My surprising conclusion? They weren't!)

At least the SD article gave a useful description of dragon boat racing:
Dragon boat racing is an ancient Chinese sport dating back to the 4th century BCE. The boats are long, narrow, canoe-like craft, crewed by teams of anywhere from 10 to 20 paddlers, plus a drummer at the bow and a tiller (or steerer) at the stern. Once restricted to China and to Chinese expatriate communities, over the last quarter-century the sport has become increasingly popular worldwide, particularly on Canada's west coast.

(Photo Credit: Dr. Catherine Sabiston)