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Saturday, February 2, 2013

Tomol Construction

A Chumash tomol. Painting by Robert Thomas. Click any image to enlarge.

In our previous post, we looked at social and economic aspects of the California Chumash planked canoe or tomol. Now let's see how they were built.

The primary construction materials were softwood for planking, asphaltum (i.e., bitumen) and pine pitch for sealing, and red milkweed for caulking and sewing. Redwood was the preferred wood, because of its light weight, durability, rot resistance, and ease of working. Redwood is not native to the Santa Barbara region where the Chumash lived, but a fair amount turned up as driftwood, primarily on the shores on the Channel Islands. Far less redwood driftwood was available on the mainland on the other side of the Santa Barbara channel. On the other hand, bitumen was easily mined on the mainland from exposed coastal cliff faces, so most tomols were built on the islands with bitumen imported from the mainland. But because of the economic importance of the tomol, they were built wherever possible, including on the mainland, and if redwood was unavailable, other softwoods were used.

Tree trunks were split into planks with wedges made from whalebone. The quality of the planking material was of such concern that a log might only yield a few planks acceptably free of knots, cracks and bad grain. After being split, planks were further worked to consistent thickness with axes and adzes made of stone or shell, then smoothed with sharkskin "sandpaper."

The tomol was built right side up. The bottom plank was somewhat dished, but it was not thick enough to constitute a "dugout" base: in other words, the tomol was a true plank-built boat, not an extended dugout. The bottom plank was set on a V-shaped framework that established the angle of the sides. (It's not clear to me from the available materials whether this was a single building form located amidships, or a series of connected forms -- i.e., a building frame -- that determined the shape at several stations.)

Each strake consisted of several short planks which were beveled at the ends to make lap joints. The strake-to-strake joints were butted and had caulking bevels, like standard carvel planking. The garboards, which were set on top of the bottom plank, were beveled to establish the proper angle for the sides.

Fitting the planks was probably the most difficult and time-consuming task in tomol construction. A complex series of lines was strung as guides to each plank's shape. On occasion, it was possible to get out a plank with the proper curves from a suitably curved piece of timber; at other times, a plank might be hewn to the required curved shape. Most planks, however, had to be sprung in place. To soften them, they were placed in clay-lined, water-filled pit, and hot rocks were added to boil the water. After the planks had soaked for some hours, they were removed and quickly bent and twisted to shape on the boat. They were bedded in yop -- a mixture of bitumen and pitch pine.

Pairs of holes were bored in adjacent planks with stone drills, and grooves cut between the holes. Waxed cordage made of red milkweed fiber was passed through the holes: each stitch consisted of three turns, followed by two knots. (Cordage was made by women; men performed all other tasks associated with construction.) All stitches were separate. The ties were recessed into the surface of the plank, and so were protected from abrasion. Plank laps were stitched in a similar manner. More milkweed fiber was forced into the planking bevels. All plank joints and tie-holes were sealed with more yop.

A tomol built in 1912 or 1913 for anthropologist John Peabody Harrington by Fernando Librado, the last Chumash to have worked with the old "Brotherhood of the Tomol" boatbuilders guild.
Most tomols had six strakes. A single thwart was placed amidships, sandwiched between the fifth and sixth (gunwale) strakes. This was the only internal strengthening member, and it was never used as a seat. The first five strakes were apparently beveled to meet at the bow and stern (where they were stitched together): the gunwale strakes stopped just short of one another, leaving a V-shaped gap at the ends through which fishing or harpoon lines could run. Half-round "ears" were sewn atop the ends of the gunwale strakes, raising the height of the V. While claims are made that these served as washboards, they appear too small to have been functional: I believe they were primarily decorative. A rope was passed around the both ends, just inboard of the ears, to keep the uppermost strakes from spreading.

After planking was complete, internal stem- and sternposts were added. These were triangular in cross-section and extended from the bottom plank to the top of the fifth strake, and were fastened with yop and stitches.

Excess yop was then scraped off and the wood was sanded again and sealed with pine pitch. Red ochre was added to the pitch for color. Using a raccoon-tail brush, all stitches were painted black. The ears were often decorated with shell inlays in geometric patterns, and occasionally crushed abalone shell was dusted onto the pine pitch sealant while it was still tacky: this made the whole boat sparkle in the sunlight.

Helek, a replica tomol (26.5' LOA) built in 1976.
Construction of a tomol took two to six months for seven workers– a really significant outlay of labor and resources for a hunter-gatherer society. The boats were highly valued and received daily maintenance. Although they leaked badly and required almost constant bailing, they were seaworthy and well-suited to the needs of their builders. According to a Spanish sea captain's report in 1602:
After the Spanish settled the Santa Barbara region, Chumash boatbuilders produced tomols for the Spanish missions, which relied on them for communications and trade. The design of the tomol did not change, but the Spanish made sawn lumber and steel tools available, and this must have greatly telescoped the building process. 

A tomol replica: does anyone know where this is and who built it?

Jeanne E. Arnold, "Credit Where Credit is Due: The History of the Chumash Oceangoing Plank Canoe," American Antiquity, 72(2), 2007, pp. 196-209
Dee Travis Hudson, "Chumash Canoes of Mission Santa Barbara: the Revolt of 1824," Journal of California Anthropology, 1976
Brian Fagan, "The Chumash," in Time Detectives. New York: Simon & Schuster, 1995


  1. Interesting, Bob, that what we think of as European construction was found here prior to that influence. We often think that metal tools were required to do this kind of work. Of course, the redwood or cedar that was available splits very evenly and makes perfect planks because of how much they swell when wet.

    If the top plank doesn't connect to the stem, transom or frames, I would call it a washboard. But I suppose I'm being pedantic. This feature was also common in Japan and Italy, which raises all kinds of questions in my mind. The Asians could have easily influenced both cultures at some point.

  2. Doryman: Washboard does seem to be a good term for that top strake. Thanks.
    There's a popular theory that the tomol was imported from Hawaii, where one fully stitched plank canoe existed (which happened to differ from the tomol is just about every other respect possible). I haven't mentioned it in the posts because in my opinion, the argument was effectively rebutted in the Arnold text cited in my sources. I tend to be skeptical of diffusionism. Certainly it occurred in many places and at many times, but parallel development often provides a more parsimonious explanation and I think that's the case here. Occam's Razor and all that.
    The notion of a stitched-planked boat is not so "out there" that various cultures might not have arrived at it independently. The Hawaiians and Chumash implemented that notion in very dissimilar manners (e.g., the Hawaiian boat was 5-6 times as big as the tomol, and it was an round-hulled, outrigger sailboat, not a dory-shaped monohull propelled by double-bladed paddles [which are unknown in the Pacific]). I'd want to see greater similarity in execution, and more than a single pair of possible cognate words between the two cultures, before I'd begin to accept diffusion.

  3. Hello Bob,

    That Chumash red tomol replica is actually not at the Santa Barbara Natural Museum of Natural History or at least not on display. The museum does, however, have the tomol built by Fernando Librado that you mention. You can see a photo of Librado's tomol on my blog at the following address:


  4. Thanks Jack. I've updated the caption for that photo to reflect your input.

  5. Any one have lines and dimensions for a scale model bow and transom angle tumble too beam to loa length at waterline?

  6. Anonymous: fair question, but if you want anyone to answer, anonymity is perhaps inadvisable.