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Thursday, February 16, 2017

The Yathra Dhoni - A Single-Outrigger Ship of Sri Lanka

yathra dhoni beached
The large vessel is a yathra dhoni. Its outrigger allows it to sit upright on the beach without temporary supports (from Devendra, "The Lost Ships of Lanka.") (Click any image to enlarge)
Seagoing ships with outriggers are a rarity. If one defines “ships” as “(floating mobile nautical) structures which constituted significant elements in the economies of the societies which built and operated them” (Basil Greenhill, in The Earliest Ships: The Evolution of Boats into Ships), then a few of the larger traditional single-outrigger canoes of Oceania would qualify, but based on their size, burthen, and the fact that they are “canoes,” most modern observers would still call them “boats” without hesitation. Some motorized bancas of the Philippines might be (just) large enough to be thought ship-like by some, but no one of these double-outrigger vessels would qualify on the grounds of economic significance.

The yathra dhoni of Sri Lanka and the Coromandel Coast on India, then, may be the only traditional outrigger vessel that was undeniably a “ship.” Large and burthensome enough so as not to be mistaken for a boat, and used as a cargo carrier on both coastal and short oceanic voyages, the single-outrigger yathra dhoni (also spelled yatra dhoni, and also known as the maha-oruwa or maha oru, meaning “big outrigger canoe”) was in use for centuries – possibly thousands of years – and remained in common use into the early twentieth century.

Admiral Paris's drawing of a yathra dhoni
Admiral Paris's drawing of a yathra dhoni (from Essai sur la construction navale des peuples extra-européens ou Collection des navires et pirogues construits par les habitants de l'Asie, de la Malaisie, du Grand Océan et de l'Amérique dessinés et mesurés pendant les voyages autour du monde de "l'Astrolabe", "la Favorite" et "l'Artémise")
Outrigger ships in Sri Lanka were noted by Strabo (65 BCE-19 CE) and Pliny (23-79 CE), and if these were not yathra dhonies per se, they were probably their direct ancestors. A temple carving in Borobudur, Java, dated to the 8th to 10th century CE, shows “the arrival of Aryan emigrants to the Indonesian Islands” (Vitharana) in an outrigger vessel with features similar to the yathra. (The original Aryans, however, were from the area that is now northern India, not Coromandel or Sri Lanka.) Near the end of their history, yathras were known to be trading as far as the Moluccas, so their earlier use transporting Aryans or their neighbors to Java (which, like the Moluccas, is in Indonesia, but closer to India) seems credible.

Most yathras were 50 to 60 feet LOA with a main hull beam of 12 to 15 feet. The largest were 100 feet long with a 20 foot hull beam. Vitharana states that they were 10 to 15 feet in height, although it is unclear what points of measurement are implied. Cargoes ranged from 25 to 75 tonnes, with 50 being typical. The main hull was double-ended, with slack bilges, full midsections, and a slightly hollow entry.

Vosmer's drawing of Dodanduva yathra dhoni model
Tom Vosmer's profile drawing of the Dodanduva yathra dhoni model (from Devendra, "The Lost Ships of Lanka)
The outrigger varied in length, from about a third (Paris) to well over two-thirds (Vosmer’s drawing of a highly detailed model built in the former yathra center of Dodanduva, Sri Lanka, that is widely accepted for its authority) the length of the main hull. It was always mounted on the port side, fastened directly to substantial, downward-curving booms that extended right through the main hull at the level of the deck beams. (One simplified model exists with the outrigger to starboard, but this model lacks a rudder and may represent a different vessel type, or the difference may be due to imprecision on the modeler’s part.) Guys leading diagonally from the main hull to the outer ends of the outrigger booms helped stabilize the outrigger float fore-and-aft.

Dodanduva model of a yathra dhoni
The Dodanduva model of a yathra dhoni (from Green) 
The yathra’s rudder followed the curve of the sternpost. The rudder on the Dodanduva model is enormous and wide, but other reliable sources show rudders of more graceful shape and conventional proportions. From this, it appears that rudders were fitted in a range of sizes and styles. Vitharana refers to a “secondary rudder to act as a leeboard … in the region of the main mast touching the water on the starboard side,” but in no models or drawings that I know of does such a feature appear. A leeboard would appear to be unnecessary, since the hull was built on a keel that provided significant lateral plane to resist leeway. Some models and drawings also show a “gripe” at the bow and a skeg at the stern (upon which the rudder’s lower end was hung), both of which added to the lateral plane and directional stability.

Hornell's sketch of a yathra dhoni
Hornell's sketch of a yathra dhoni
The common rig was a ketch with square headed, loose-footed cloth lugsails and a jib on a bowsprit, said by Green to be “a rig common to the region of the Indian subcontinent.” Some smaller yathras may have had a single mast. Hornell’s sketch of the ketch version shows a second headsail inside the first one, apparently set flying, with its tack led to the port bulwark or possibly to the foredeck. Admiral Paris’s drawing shows a whisker pole holding out the luff of the mainsail. Standing rigging included shrouds, fore- and backstays, and a stay between the mastheads. According to Green, “The arrangement of the halyards was such that they prevent the mizzen yard from passing around the forward side of the mast. It must therefore be concluded that the mizzen sail on the yatra was never tacked, but went aback against the mast when occasionally on a starboard tack.”

Two bulkheads divided the hull into three sections: small bow and stern compartments, the use of which I have not found described, and a large cargo hold between them. Much of the deck was covered by a light, removable deckhouse roofed with split bamboo, leaving only narrow walkways along the sides for the crew to move fore and aft. Sliding cargo hatches were offset to starboard, and a simple cargo handling crane was located to port. In order for this to come in use, lighters – probably small dugout canoes – must have come alongside the main hull between the outrigger booms. But because the vessel would sit upright on a beach, supported by the outrigger, it may be that loading and unloading was often done on land. One assumes that the deckhouse roof was removed before cargo was handled.

The hull of the yathra was of a carvel construction using an unusual combination of stitched and nailed fastening. The planks, a minimum of 2” thick, were stitched to each other with coir rope and nailed to the frames with iron nails and roves. Accounts differ on whether the stitching holes penetrated straight through to the inner surface of the planks or exited on the plank edges. In any case, it is clear that the stitching served only to hold the planks against each other and not to the frames. Details on the order of construction are lacking, but one presumes that the planks were stitched first to make them tight, and nailed second. Joints were caulked with coconut husks and leaves inserted before the stitches were drawn tight.

yathra dhoni construction drawings
Vosmer's construction drawings of the Dodanduva yathra dhoni model (from Devendra, "Pre-Modern Sri Lankan Ships")
Stem and sternpost were fastened to the keel with hooked scarfs held with locking wedges. The frames and deck beams were few in number and widely spaced but of heavy scantlings, providing sufficient overall strength. Deck beams extended through the planking on both sides. Green says the frames were continuous from sheer to sheer, but given their scantlings and the hull’s shape, this seems impossible. Perhaps his information, which is not footnoted, stems from observation of a model which used continuous frames for expediency.

Tom Vosmer took careful measurements of the Dodanduva model, fed the details into a hydrostatics program, and found that the main hull, even without the outrigger, was “reasonably stable.” The outrigger, of course, significantly increased the vessel’s righting moment (by a factor of 100). It also increased drag, and therefore, the ship’s powering requirements. The rig, therefore, could have been smaller and simpler if the (still seaworthy) hull did not have an outrigger attached.

Yathra dhoni at anchor in Kalpitiya, Sri Lanka
Yathra dhoni at anchor in Kalpitiya, Sri Lanka, 1913 (from Devendra, "The Lost Ships of Lanka") 
Yathras were mainly short- and medium-haul cargo vessels, serving ports large and small throughout Sri Lanka and the Coromandel Coast and making regular voyages to the Maldives (550 miles from Colombo, Sri Lanka), although they also sailed at least occasionally to the Moluccas (3,600 miles). Typical cargoes included textiles, rice, salt, fish and fish products, tea, and tiles. A large one carried a crew of 18.

The outrigger was always kept to windward except, perhaps, in the most benign conditions – an unusual and highly limiting practice for a tacking single-outrigger vessel. Working within these limits required coastal voyages to make use of the daily reversal of land and sea breezes: the vessel sailed only during the part of day when the prevailing breeze allowed the outrigger to be kept to windward. On longer voyages, the monsoon breeze dictated direction. This would have meant just a single round trip from Sri Lanka to the Maldives in any given year, whereas a vessel that could sail with either side to windward would be able to make several round trip voyages of that distance each year.

Most accounts tell of the yathra succumbing to competition from steamships around the turn of the twentieth century. Vitharana claims that 40 of them were still serving Dodanduva in the 1930s, but all other accounts tell of the last one being built there to some fanfare in 1930; that is was wrecked on its first voyage in the Maldives; and that that was the end of the tradition.

Sources:
Somasiri Devendra, "Pre-Modern Sri Lankan Ships" in Ships and the Development of Maritime Technology in the Indian Ocean, David Parkin gand Ruth Barnes, editors. Routledge, 2002
Devendra, "The Lost Ships of Lanka," from Maritime Heritage of Lanka: Ancient ports and harbours. National Heritage Trust Sri Lanka, 2013
Devendra, "The Mansion of the Sea," The Island Online - Saturday Magazine
Jeremy Green, "The archaeological contribute to the knowledge of the extra-European shipbuilding at the time of the Medieval and Modern Iberian-Atlantic tradition" Proceedings: International Symposium on Archaeology of Medieval and Modern Ships of Iberian-Atlantic Tradition
James Hornell, Water Transport: Origins and Early Evolution, Cambridge University Press, 1946
The National Trust of Sri Lanka, "The Annapoorani and The Amugoda Oruwa: The Forgotten Ships of Lanka" on Facebook
Corioli Souter, "Travellers and Traders in the Indian Ocean World Curatorial Audio Guide," WAM Audio Tours, Western Austrian Museum
Vini Vitharana, "The ORU & the YATRA" Nautical Archaeological Society, 1992, republished 2012

Wednesday, January 18, 2017

Vatican boat model exhibit, Part 3


This is the final post about a current exhibit of boat models and canoe paddles at the Vatican Museums. Previous posts about this exhibit cover the other models representing boats from outside the Western tradition, and one full-size canoe from the Solomon Islands. As noted in the previous posts, exhibit signage was sparse. We reproduce the English text of the exhibit cards in quotation marks. Our own comments appear in parentheses. As always, click any image to enlarge.

model: "Tahiti: Catamaran"
"Tahiti: Catamaran" (The two hulls are essentially the same but with their ends reversed. The boat should perform the same in either direction when it shunts.)
model Maori war canoe
"Aotearoa New Zealand: Maori boat" (A monohull war canoe. See our earlier post on boats like this.)
model 3-hull catamaran, New Guinea
"Papua New Guinea: Three hull catamaran" (beautiful double crab-claw rig)
model 3-hull catamaran, New Guinea
(Same model as above, showing the hull configuration.)
model New Guinea outrigger paddling canoe
"Papua New Guinea: Boat with outrigger" (The main hull is a dugout with high washstrakes stitched in place)
model Solomon Islands monohull canoe
"Solomon (Islands): Canoe with bird shaped bow" (Somewhat similar to the full-size canoe that serves as the exhibit's centerpiece.)
"Fiji: Sailing boat" (Twin-hull canoe with oceanic lateen sail)
"Fiji: Sailing boat" (Twin-hull canoe with oceanic lateen sail)
"Fiji: Sailing boat" (Twin-hull canoe with oceanic lateen sail)
(Same model as previous. The port hull is much smaller and shorter than the starboard, but it is nonetheless a true hull, not an outrigger float.)
model Alakaluf Canoe, Chile
"Chile; Alakaluf Canoe" (This looks much like the Yamana/Yaghan canoe we've written about previously.)
model kayak-form canoe
"Alaska: Canoe" (Adney called this a "kayak-form canoe.")
model Yaghan (Yamana) canoe
"Chile: Yaghan (Yamana) canoe" (Images created by Europeans show greatly different forms of Yaghan or Yamana canoes. See the Alakaluf canoe two images above.)
model bark canoe with full decks
"Canada: Canoe" (...and a rather fanciful one at that! We're not aware of any bark canoes built with full decks and a round cockpit coaming. The modeler seems to be combining aspects of the open bark canoe with the skin-on-frame kayaks of Alaska.)
model Caraja river boat, Brazil
"Brazil: Caraja river boat" (The cargo of what appears to represent a dugout canoe is probably tortoises or sea turtles. At the right is a pregnant woman; at the left, a baby.)
models, Alaska and Canada bark canoes
background: "Canada: Canoe"
foreground: "Alaska: Bark canoe"
model twin-hull raft from Bolivia
"Bolivia: Mosetenes raft" (A double-hull raft. Perhaps it is built to be separated, so that it can be used as two smaller craft.)
model reed boat, Lake Titicaca
"Peru - Bolivia: Ayamara boat"(A reed boat of the type used on Lake Titicaca.)
bark canoe models, USA
background: "Rocky Mountains: Canoe"
foreground: "USA: Canoe"
(Both are birchbark types.)
model canoes, Madagascar
background: "Madagascar: Dugout canoe"
middle-right: "Madagascar: Dugout canoe"
left: "...West Coast" (presumably Africa; we failed to capture the full label text)
front-right: "Madagascar: Dugout canoe"
model coracle, Mozambique
"Mozambique: Raft" (We'd call this a coracle, not a raft, since it relies on the enclosure of space for buoyancy. The model is made from a single piece of bent bark. If the full-size boat is built the same way, it must be quite small, or else it requires an enormously wide tree.)
model outrigger sailing canoe, Africa east coast
"Africa - East Coast: Sailing boat with outrigger" (The main hull is extraordinarily narrow and highly rockered. This must be a thrilling boat to sail.)
models Congo dugout canoes
background: "Congo: Canoe with rower" (a paddler, in fact)
foreground: "Congo: Canoe"
model boats, Nigeria
background: "Nigeria: Boat with two rowers" (paddlers)
middle: "Nigeria: Boat with passengers"
front: "Nigeria: Boat with passengers"
(All three represent dugouts with an aft platform carved as an integral part of the hull for the stern paddler/helmsman. Locating the paddle force so far aft of the submerged part of the hull lends a great deal of power for turning and correcting strokes, making these boats highly maneuverable.) 
model Yoruba dugout canoes, Nigeria
"Nigeria: Yoruba boats: H.E. Mons, Carlo Maria Viganò" (These were the only models in the exhibit credited to whom we assume was the donor or lender.)
canoe paddle display, Vatican Museums
A nice selection of canoe paddles were exhibited at the end of each of the spiral levels of the hall, unfortunately with no exhibit cards or other identification. (This photo by Cate Monroe)
canoe paddle display, Vatican Museums
A closer look at the paddles on the middle level.

(All images by the blogger except as noted.)

Wednesday, January 4, 2017

Vatican boat model exhibit, Part 2

In a current temporary exhibit at the Vatican Museums, dozens of models of watercraft from numerous nations and cultures are presented to represent the diversity and interconnectedness of humanity. (See our previous post on this exhibit.) The models are displayed in glass cases (hence the poor quality of the photos that follow) with little explanatory material. 

We present our photos with the scanty information from the exhibit cards in quotation marks, and our own brief observations in parentheses. We invite readers to contribute additional information about any boat in the Comments. Only models representing craft from "outside the Western tradition" are included here. More images of other models from the exhibit will follow in a subsequent post. As always, click any image to enlarge.
"Japan: Sailing boat" (looks like it would be highly capable in surf)
"Indonesia: Sailing boat with outrigger" -- (actually two outriggers. Although the rig is set as a square sail, it appears to be hung asymmetrically on the mast and can probably be canted to form a kind of lugsail.)
"Philippines: Sailing boat with outrigger" -- (again, two outriggers. This is a banca, with a Western-style sailing rig.)
"Sri Lanka: Boat with fisherman" (We wonder if the model attempts to represent any real type of boat, or if it is purely fanciful, its shape dictated by the material available to the modeler. What's surprising and touching about this model is the paddler, who is modeled with a great deal of humanity.)
"India: Pirogue with rowers" (paddlers, actually)
"China: Boat for recreation" (and by that, we mean eating, drinking and sex.)
(background) "India: Pirogue with rowers" (again, paddlers in fact)
"Thailand: Royal boat" (identical exhibit cards for both models)
"China: Sea Junk" (The truncated bow and minimal rig are fascinating aspects of this model, which is certainly not meant to be an accurate representation.)
"Southeast Asia: River boat" (a sampan)
"China: Sea Junk with three masts"
"China: River boat"
"China: Dragon boat for racing"
(Nationality not identified)
Back row:
Left: "Raft for fishing with cormorants"
Center: "Houseboat with passenger and boatmen" (Error in labeling, as this open craft is clearly not a houseboat. The Italian label identifies it as a sampan with a passenger and a boatman)
Right: (label illegible in photo)

Front row: 
Left: "Houseboat with coxswain"
Center: "Houseboat with passenger and boatmen" (Error in labeling, as this open craft is clearly not a houseboat. The Italian label identifies it as a sampan with a passenger and a boatman)
Right: "Houseboat with fisherman"
"Samoa: Seven paddle canoe" (Noticeable similarities to a Samoan canoe in our post about Buckminster Fuller's model collection)