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Wednesday, July 9, 2014

Two Current Bits of Nautical Archaeology

Mars was the largest ship in the world in its day. It exploded and sank during a battle in 1564.
Swedish warship Mars

A couple of quick marine achaeology links:

Recent news about the discovery of the remarkably intact 16th-century three-masted Swedish warship Mars. Not within our definition of "indigenous boats," but fascinating nonetheless (if you ignore the ludicrous "cursed warship" in the headline of the National Geographic article). 

Reader and contributor Edwin Deady sent me this link for a free online course in marine archaeology, offered by the University of Southampton. It starts in October and, according to the description, it does address non-European examples and topics.

Wednesday, June 25, 2014

Irish Logboat Finds

An article in the current issue of Current Archaeology tells of multiple logboat finds in Lough Corrib, County Galway, Ireland. I haven't seen the full writeup (it's pay-to-read), but a decent summary appears here.

The five boats, found in various locations around the large lake, were discovered during a bathymetric survey, and they were preserved by the lake's soft mud bottom and (presumably) cold temperatures and still waters at depth. One of the logboats, dated to about 4,500 BCE (Early Bronze Age), exhibits 2-3cm raised features carved on the inner side of the hull. There is a lengthwise feature that serves as a kind of keelson, and four cross-members. The article speculates that these served to divide the hull into compartments, but I think it more likely that they served as strengthening members in the nature of ribs.
Bronze Age Irish logboat (Source Current Archaeology)
The Early Bronze Age logboat found in Lough Corrib is 12 meters long and probably had a crew of 10-12 paddlers. (Source: Current Archaeology)
A 3,400-year-old boat was apparently carved in two halves, held together by rods that passed through internal cleats on the interior of both halves, and probably supplemented by lashings through bored holes. (The article summary is ambiguous on this point.) This strongly suggests kinship with the sewn-construction techniques used in England, as displayed in the Bronze Age Ferriby boats and Dover boat.

Another Lough Corrib boat, dated to the 11th century CE, was found in conjunction with several battle axes. Although battle axes were introduced to Ireland by Vikings a couple centuries earlier, the article states that it is more likely that the boat carried Irish warriors who had adopted the Viking weapon. Clear evidence for the use of oared propulsion exists in the form of holes for four pairs of tholepins. Five thwart-seats were present, indicating that the boat carried a coxswain or some other non-rowing individual (e.g., a passenger, dignitary or the captain). Clinker-planked construction was common by the 11th century, and of course skin-on-frame curraghs were also in use in Ireland at that time, so it is interesting that logboats remained in use for apparently high-prestige purposes that late in Ireland's history.

Thursday, June 19, 2014

The Australian Overlapping-Triangle Raft

Reader Geoff Cater steered me toward his fine summary page of indigenous Australian watercraft where, along with excellent images of various canoe types, there are a number of rafts.

The type that I find most intriguing consists of two triangular platforms, one stacked atop the other and facing in opposite directions. In two of the examples shown, fastening on each layer is by means by wood rods inserted through holes bored through the logs. In the model, the logs are fastened to their neighbors with thread, which may indicate lashed construction on the example from which the model was based, or might have been simply the modelmaker's expedient. Also in the model, the layers are attached to one another with a nail; it's unclear how the layers are attached in the other examples.

The photos and captions below are borrowed directly from Mr. Cater's webpage, for which thanks are given.

1931: A model raft made from six cylindrical wooden rods, collected in 1931 by Gerhard Laves from Bardi people at Cape Leveque, WA. Description: A model raft made from six cylindrical wooden rods with pointed ends and joined together with thread. A second "deck" of five pointed cylindrical wooden rods are attached to the first with a metal nail. Source: National Museum of Australia.
1931-1994: Double triangular raft, pole and paddle, Western Australia. Illustration by Xiangyi Mo. Barlow: Aboriginal Technology: Watercraft (1994) page 27. The illustration by Xiangyi Mo is possibly based on the model raft held by the NMA, above. The grass matting is possibly represents a seat or, if mixed with mud, a hearth for the fire often carried on board. Below are a punting-pole and a short-staffed spoon or pudding-stirrer paddle, as used by George Water in the photograph [below]. Their use throughout the continent and Tasmania indicates the pudding-stirrer's great antiquity, perhaps back to the last of the migrations from SE Asia.

1916: Worora youth on a mangrove tree raft (or 'kaloa'), George Water, Western Australia, 1916. Photograph by Herbert Basedow (1 of 2). Basedow, Herbert: The Australian Aboriginal. F.W. Preece & Sons, Adelaide, 1925, plate 22.
National Museum of Australia

In the model and, apparently, in the 1916 photo, the ends of the two layers line up pretty well. In the drawing, the two layers are offset, so that the logs' wider ends extend beyond the other level.

Why did the raftmakers face the two triangles in opposite directions? If two layers of logs were needed for buoyancy, it might make more sense to place the narrow ends one atop the other to form a roughly conventional "bow," since a forward-pointing triangle is more hydrodynamic. 

But as the photo shows, the bottom layer seems to provide enough buoyancy to hold the top layer and its passenger nearly or entirely clear of the water. By reversing the directions of the triangles, the logs of the top one do not nestle between the logs of the bottom one, so the top one actually rides higher and drier, while the forward-pointing triangle on the bottom still provides the desirable hydrodynamic efficiency.

Both the drawing and the photo show short, one-handed "pudding stirrer" paddles, and the drawing shows a pole as well: no doubt poles were commonly used for propulsion in shallow water.