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Tuesday, October 1, 2013

A Catamaran with an Outrigger?

A recent BBC story concerning a possibly marine-related archaeological discovery in Wales reports some off-the-wall speculation about the find's significance. (Before going further, I must acknowledge that general news media like the BBC are often poor sources of information on scientific issues, and the reporting might badly misstate the facts.)

Three closely-spaced channels were discovered dug into the ground near the site of a vanished lake in Monmouth. All are 30m long; two adjacent ones are 1m wide, and the third beside them is narrower. The channels appeared over a mound of charcoal that has been carbon-dated to the Bronze Age (2,500 to 800 BCE in Britain).

According to Stephen Clarke of the Monmouth Archaeological Society, the find represents a kind of launching ramp for a Bronze boatbuilding facility. Although no boat remains or evidence of woodworking have been found at the site, artistic reconstructions show the site used to launch a canoe with twin dugout hulls and an outrigger.

Everything about this interpretation seems misinformed. To start with the boat:
  • The use of monohull dugouts in Bronze Age Britain is well proven. There is no prior evidence for multi-hulls.
  • A twin-hulled canoe of the size and breadth shown in the reconstruction would provide more than enough stability for any conceivable conditions on a lake. The outrigger serves no conceivable purpose. (Has any boat anywhere, used on any waters, ever had two main hulls plus an outrigger? I doubt it.) 
  • If the site was indeed a boat launch, three alternatives offer more likely and practical interpretations: i. three monohulls (two wide, one narrow); ii. a twin-hulled canoe and a narrow monohull; or iii. an outrigger canoe and a wide monohull.
  • There is also no evidence for the use of sails in Britain's Bronze Age, although a mast is shown in both reconstructions, and a sail in the line drawing.

But even the notion that the site represents a boatbuilding facility, or any sort of boat-related facility, cannot be accepted so easily. Aside from the absence of woodworking or boat-related artifacts, the trenches make little sense for the purpose of boat launching. If one wanted to drag a heavy boat up and down the shore, the last thing he would do is carve channels that would increase friction around the hulls. Friction would be much lower if the rounded hulls rested on a flat plane, and flat ground would also permit the use of rollers or, if the ground was too soft or sticky, launching ways similar to Hawaiian canoe ladders.

Even if the trenches did make sense as a launch ramp, there is no reason for them to have been so long. Assuming that the color illustration is accurate in its depiction of the slope of the shore and the trenches' location relative to the water level, the trenches extend much farther than necessary to haul the boat(s) entirely out of the (non-tidal) lake. The amount of extra work that would have been required to dig the trenches, and to haul the boat any farther than just out of the water, makes its use as a boat launch unlikely.

One final item: since the trenches were found above the charcoal, they must be of more recent origin. Britain's Bronze Age lasted for 1700 years or so, and the article doesn't report the exact carbon-dated age of the charcoal, but from the information available, it seems possible that the trenches were dug after the end of the Bronze Age.

I have no better, alternate interpretation for the find, but the current one seems to be based on a poor understanding of boats and how they are used. The BBC article claims that Mr. Clarke has a book on the subject in the works: this promises to be a fanciful piece of pseudo-archaeology, akin, perhaps, to the laughable and inexplicably well-known The Life and Death of a Druid Prince.

(Thanks to Edwin Deady for pointing out the BBC article.)
(Both images are from the BBC article.)

Update (2 Oct., 2013): This article by the Daily Mail contradicts some details of the BBC article, and provides useful photos of the excavated channels. It states that the channels were cut through the charcoal deposits (dated to the early Bronze age), not over them. And it reports possible evidence of woodworking at the site, in the form of "sharp flakes of imported flint found alongside the channels." The article claims that "Prehistoric cave drawings in Scandanavia (sic) have been discovered depicting outrigger boats like the one built at Monmouth," but provides no backup for this statement. The images it shows of "similar" boats of the historic period depict double canoes and single-outrigger canoes, but no double canoes with outriggers.
(Thanks to Tom Rankin for pointing out the Daily Mail article.)


  1. i've tweeted the history yesterday even when i saw the images, find it some strange for the same reason: a catamaran with an outrigger?
    thanks for your critical view

  2. Much as I would love there to be real evidence for the use of British prehistoric outriggers I accept that htis is not it. The solution for gaining extra stability in Britain seems to have been based on the idea of splitting the loggboat down the middle and adding an extra plank. Speculative because we don't have the "missing link" but apart from logboats themselves all British indigenous boat are based on the three bottom plank principle from the Ferriby Bronze Age boats to the Severn Salmon punt including the turf boats and flatties of Somerset and Norfolk along with the assorted flat-bottomed beach boats along the South coast.

    1. Sorry I didn't see this article earlier.
      The main points raised are that there's no evidence of British outriggers and secondly no need for an outrigger on a twin canoe. Wrong on both points. Look up the Lurgan boat which is clearly one and then look up Fiji twin canoes with outriggers – there are descriptions and drawings of them during the 19th century; and we do have evidence of woodworking with flint tools in the channels. Steve Clarke

  3. Mr. Clarke: Would be very interested in seeing the evidence you mention. Please provide us with some links or at least citations. Better yet, send me the articles: bob (at) yournameherecom.com. Thanks.

    1. Dear Robert,
      As you are clearly interested I'm happy to send you a copy of the book
      Ours is an interpretation of an archaeological record – I've been digging for over half a century (no recommedation, I know!) but I have never seen anything like the features on the edge of the post-glacial lake. Our interpretation is supported by so much evidence that it seems irrefutable - but of course, being an archaeologist I must be prepared to be proved wrong - it's theoretical as we don't have a boat but I'm hoping that someone will recognise similar features elsewhere. Being a bit of a dinosaur I'm not used to this form of communication – can I include a longer reply ?
      Thanks/Diolch yn fawr,
      Steve Clarke, Monmouth, Wales

  4. Dear Bob
    I'll be happy to send you a copy of the book
    or can I reply in more detail - I'm new to this sort of communcation.
    Hwyl Fawr – Steve Clarke
    Steve Clarke

  5. Steve,
    Thanks. Photocopies of the pertinent pages will suffice -- no need to send the whole book. I'm at 15 Keller Dr., Rockport, ME, 04856, USA. Scans to my email would also do fine if you have the technology.
    I don't believe there's a limit to the length of replies in the Comments, so feel free to answer at any length you wish. Alternately, I'd be glad to run your point-by-point refutation of my post in its own post, where it would be more visible. If you wish, you can send a longer piece to me by post or email.
    And please accept my apology for the insulting tone of my post. It wasn't called for and I'm ashamed to have so treated you.
    All best,

    1. Dear Bob,
      I can't get your e-mail to work (if it was one). I'll try a longer note but may well send a book in any case – I'm sure that you are far more experienced than me in this aspect – I've been digging for too many years not to know that we might be wrong, although I feel that our evidence is pretty solid.
      My longer note is too long so will try breaking it up
      Part 1.
      WITH EVIDENCE from the shores of a post-glacial lake, the authors present their interpretation that Bronze Age twin canoes with outriggers were being constructed in clay channels and slid out onto the lake. A Wye Valley lake had formed from melting ice sheets some 11,000 years ago and attracted human settlement almost continuously from the Stone Age to the Iron Age. The story of prehistoric boat-building is woven around the Welsh Border town of Monmouth which occupies a peninsula on the edge of the vanished lake.
      In 1999, archaeologists were digging inside an empty shop in the town when they found a very water-worn Bronze Age flint arrowhead inside a pebbly beach some six metres higher than the town's rivers. Twelve years later, Iron Age pottery and a Mesolithic camp site were found beneath a similar shoreline in a gas main trench on the other side of the town. These and other discoveries could only be explained by the survival, almost into historic times, of the post-glacial lake – a fact supported by material and radiocarbon dates from the bed of the lake. Much of today's town would have been under about six metres of water while the lake itself, being some 4 kilometres across, would have been bigger than any in southern Wales today.
      A watching brief during a housing development on low-lying ground overlooking the western side of the lake – at Parc Glyndŵr – revealed six drifts of Bronze Age fired stones for boiling water (burnt mounds), a New Stone Age hearth and Iron Age remains on the bed of the lake. These vestiges covered an area of just sixty metres and it was here that the greatest mystery also arose – apparently unique in prehistoric archaeology.
      Two shallow channels with boat-shaped bottoms and a smaller trapezoidal-shaped one had naturally filled with anaerobic clay and were found to be running at right angles to the lake. The channels were thirty metres long and closely associated with the abandonment of a burnt mound which produced Bronze Age pottery and a radiocarbon date of c1680BC. All three channels were level and perfectly parallel to each other, as if they were the base for the construction and moving of a frame of some sort; the channels only produced clean sharp flakes of imported flint – seen as evidence of woodworking with flint tools. The remains were sealed by a metre of alluvial clay.
      Archaeologist Jane Bray and maritime engineer Gordon McDonald suggested that the channels formed a matrix for the construction and launching of a prehistoric twin-hulled craft with an outrigger. Vessels with outriggers are depicted in Scandinavian Bronze Age rock art where the outriggers are shown as quite separate to the main boat but clearly linked to it by cross beams. Another suggestion that twin canoes would not have outriggers is also erroneous for drawings and descriptions survive of twin canoes with outriggers in action in 19th century Fiji.

    2. Part 2. from Steve Clarke, Wales
      The chances of more stable vessels like these being preserved in wetlands must be lower than that of single canoes - of which scores have been found in Western Europe. Like Darwin's missing links, this is probably down to chance, but also because outriggers would more often end life against dry land and be broken up for spares or for firewood. This must also be the case with Bronze Age sewn boats where only a dozen fragments are known from the British Isles.
      However, it appears that at least one combination craft has been found – at Lurgan in Ireland. It has a series of paired holes along its side which the authors say can only be explained as fixing points for the attachment of either another logboat or of stabilisers of some kind and they consider it likely to have been a sea-going vessel. The boat is 15m long and 1m wide and part of a similar vessel was found at nearby Carrowneden. The Irish boats are of a similar period to the Parc Glyndŵr burnt mound which was closely cut by the channels (with a radiocarbon date of 3700 ± 35 BP). The Lurgan boat radiocarbon date was 3940 ± 25 BP and the Carrowneden one 3890 ± 80 BP. The Parc Glyndŵr Channel 3 is, like the Lurgan boat, 1m wide.
      Well over a hectare of ground around the channels was excavated, proving conclusively that the channels were not part of some ancient agricultural or water management system. Far larger areas across the site were stripped or trenched during the construction of 85 houses but no comparable features were revealed.
      Prior to the industrial revolution technologies changed little, so it should be no real surprise that the earliest 'boatyard' excavated should have almost identical features to those at Parc Glyndŵr – even though they were thousands of years apart. At Smallhythe, in Kent, a 15th century vessel was constructed in a level channel, shaped like the bottom of a boat, and dug at right angles to the estuary – just above high tide level. Surprisingly, there was none of the expected dry docks, slipways or inlets into the estuary. The evidence for wood working in the channels came from ships' nails at Smallhythe and the flint flakes (mostly on the sides of the channels) at Parc Glyndŵr. On both sites the completed vessels could have been slid straight out on to the water. Today, Smallhythe and Monmouth are far from the sea but both were surrounded by the raw materials of heavy woodland and ample plastic clay.

      Stephen Clarke, MBE, FSA, MIfA, is a professional archaeologist with fifty years’ field experience. His team has received several British Archaeological Awards including that for the greatest initiative in archaeology - the Silver Trowel.

  6. Is it possible that the lake level was higher at the time these channels were dug and used and the channels were filled with water? In this case there would not be increased friction but the channels would allow loading and unloading of the vessel from dry land - sort of the reversal of a dock. This would make perfect sense for a heavy vessel that would otherwise be very difficult to drag out of the lake. Also the lake level would not be greatly variable as would an ocean/sea site with tidal variations.

    If the channels were used for individual boats why would they need to be parallel? Wouldn't it be just as likely the channels would have been made somewhat randomly in that case?

    The BBC comment seems at once defensive and uppity. There is a good deal of quality science reporting on BBC.