Bronze Age wrecks and Viking-style  battleaxes from Lough Corrib, Ireland

For up to 4,500 years, a series of sunken dug-out canoes have been lying, forgotten, on the bottom of Lough Corrib in Co. Galway. Now these vessels are beginning to surrender their secrets once more, in an investigation by Ireland’s Underwater Archaeology Unit, spearheaded by Karl Brady.

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A diver from the National Monuments Service’s Underwater Archaeology Unit records a 12m-long Bronze Age logboat, one of a number of vessels recently discovered at the bottom of Lough Corrib in Ireland.

Precisely what happened that 11th-century day on the waters of Lough Corrib is lost in the mists of time, but one thing is certain: it was an ignominious end to what should have been an ostentatious journey. Earlier, a Medieval Irish dignitary had set out across the vast lake — which covers 176km ² of what is now Co. Galway — in a finely crafted logboat. Propelled by four rowers, the 6m-long vessel would have skimmed swiftly over the waters. But while the crew had their battleaxes safely stowed beside them, this was no raiding expedition: a number of unusual items had also been placed in the vessel’s hull, including a slab of red sandstone, and a rock rich in fossils; neither object was common to the local geology. Perhaps these curiosities were intended as gifts for one of the many monastic communities scattered around the edge of the lake. They would never reach their destination, however.

What came next is unclear, but several possible scenarios can be devised. Most likely is that the weather took a sudden turn for the worse and the lake became choppy, as it often does today. A narrow vessel like the logboat would have been tossed about by the waves, perhaps striking a rock jutting out from the lakebed only a short distance from where the wreck was found. Certainly a large split in the hull, which had been shaved to just 2cm thick, suggests a fatal encounter with a hard object. But might the boat’s cargo have been its undoing? As the sandstone slab was found directly over the breach, it is easy to imagine a sequence of events in which the logboat violently lurched over a wave, causing crew and cargo to bounce, and the heavy slab to come down hard on the delicate hull, cracking it open. With the vessel taking on water, there was no alternative but to make for shore with as much haste as the rowers could muster. Their situation was hopeless, however. With the vessel still 500m from land, her crew was forced to jump overboard and swim to safety, leaving the boat — and their possessions — to founder.

Locating the logboats

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Lough Corrib’s shores, and its hundreds of islands, are speckled with known archaeological sites, from Bronze Age cairns and Medieval monasteries to the ruins of a 13th-century castle, but until recently few had explored beneath its surface.

It would be a thousand years before the wreck was discovered. Although a wealth of sites, particularly Medieval ecclesiastical settlements, have been located and explored on the lake’s shore and among the hundreds of islands studding its surface, previously little archaeological attention had been paid to what lay in its depths. This has now changed, thanks to a project by marine surveyor Captain Trevor Northage to produce up-to-date navigation charts of Lough Corrib. As the lake was last charted in the 19th century, this undertaking offers obvious benefits for the fishing boats that ply its relatively shallow waters — but with an added archaeological bonus: Trevor’s sonar sweeps highlighted a number of previously undetected sites.

‘While the 1846 survey of Lough Corrib was a technical feat in its own right, it was not even approaching what I would call a reasonable chart by today’s standards — I had already damaged my own propeller, as had many friends, when I decided to have a go at charting it properly,’ said Trevor. ‘I use sidescan technology to help locate hazards, which generates enormous amounts of data that I analyse in my spare time. If I see any anomalies that look interesting, I go  back and pop the dropcamera in the water for verification, and then send the results off to the Underwater Archaeology Unit.’

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Marine surveyor Trevor Northage’s sonar picked up this distinctive anomaly, later identified as the 4,500-year-old Annaghkeen logboat, during a mapping project of the lake.

It was the appearance of a long, slender anomaly, evocative of a sunken vessel, that first prompted Trevor to contact the Unit (part of Ireland’s National Monuments Service). Responsible for all heritage sites in Irish waters, the Unit has been compiling an inventory of underwater discoveries over the last 15 years that includes more than 18,000 shipwrecks. A dive team headed by Karl Brady was sent to investigate the feature, as well as around 20 other anomalies picked up during the mapping project.

To-date, over half of these sonar ghosts have proven to be the remains of boats of various ages. Most recent is an ill-fated Victorian pleasure craft, but an ongoing programme of radiocarbon analysis and careful examination of artefacts still stowed inside some of the vessels suggests that others could be much older. Among these, five logboats have been securely dated so far, ranging from the Early Bronze Age (c.2500 BC) to the 11th century AD. Exploring the wrecks is no small task, however. Although Lough Corrib’s shallow depth is a blessing for the divers, who are able to work for long periods of time without having to factor in decompression, and can easily return to the surface to speak to colleagues or fetch additional tools — other conditions proved more challenging.

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The 4,500-year-old Annaghkeen logboat is so well preserved that the central spine and cross ridges dividing it into compartments can still be seen.

‘The bottom of the lake is very muddy: a fine, rich, sticky mud that, combined with frequent wind and rain, can mean that underwater visibility is often very bad,’ said Karl. ‘The main thing was not to touch the lakebed while recording the wrecks — if we did, it churned everything up and we had to wait for 15-20 minutes for the water to clear before we could continue working.’ While the mud was a hindrance for the researchers, it is also the reason why the logboats have survived.

The oldest and largest vessel yet identified is a 12m-long dugout, found near Annaghkeen and radiocarbon dated to 2500 BC. The craft is so well preserved that a distinctive spine some 2-3cm tall can still be seen, running the length of its floor. Four cross-ridges extend from this at right angles, dividing the boat into a number of sections — perhaps demarcating spaces for the crew, or for storage. The logboat’s impressive size suggests it was no run-of-the-mill fishing boat or cargo vessel. Noting it would have required a large crew of perhaps 10-12 to paddle it effectively, Karl proposes that the boat might have been reserved for special occasions, possibly ferrying local dignitaries across the Lough, or playing a role in ritual practices.

‘We have noticed a small patch of burning on the inside of the Annaghkeen boat,’ said Karl. ‘Not from a big fire — we are not suggesting that the boat sank because it caught fire — rather, it could reflect how the boat was made: it could be that fire was used to help loosen or soften the wood during the hollowing-out process. Alternatively, you might imagine its occupants making offerings to the water gods, carefully lighting a small fire to burn them in the middle of the lake.’

The idea of lighting a fire inside a wooden boat is not as counterintuitive as it might seem: burning was also noted inside one of the Bronze Age logboats found at Must Farm, Cambridgeshire, in 2011 (CA 263), which was interpreted as the remains of a hearth used to warm the crew as they went about their business.

Sewn planks and spearheads

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Parts of the hull of the Lee’s Island boat were joined using wooden cleats and rods, the earliest known example of this technique in Ireland, with similarities to the Ferriby Boats found in North Yorkshire.

If the traces of burning are a clue to Bronze Age construction techniques, they are not the only ones to have surfaced during this research: ancient repairs performed on a 3,400-year-old logboat located off Lee’s Island show signs of experimentation with cutting-edge methods that were only just beginning to arrive in Ireland during this period. Although only the base and lower parts of the Lee’s Island logboat hull remain, details of its construction have survived, including a series of cleats — essentially wooden loops that had been set into its floor — anchoring the slender rods that held two sections of the hull together. It is the earliest known example of this technique being used in Ireland.

Traces of a another pioneering approach are preserved at the stern end of the boat, where several splits in the hull have been stitched back together using flexible strips of yew, combined with moss caulking to ensure the repair was watertight. Developed before iron was available to nail timbers together, this technique — known as the sewn-plank method — represents the next technological step from logboats (see CA 275 for more on prehistoric boatbuilding). Three particularly wellpreserved examples of sewn boats were discovered in Ferriby, East Yorkshire (CA 291), yielding radiocarbon dates that ranged from 2030 to 1680 BC. Two of these also use cleats and rods, as seen in the Lee’s Island boat. Over in Ireland, however, contemporary communities seem to have continued to use skin boats and dug-out canoes. Dating to 1400 BC, the Lee’s Island craft demonstrates that by then knowledge of this technique was already firmly established in the west of Ireland, even if it was not being used to make entire boats.

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Spears were a common feature of several of the boats, with a complete yew shaft and a bronze spearhead recovered from the Killbeg vessel.

‘Many features of the Lee’s Island boat are similar to those found in British sewn-plank boats,’ said Karl. ‘It fits into a wider picture of changes taking place in the region at this time — other finds in the North Galway/South Mayo area suggest that Bronze Age communities were already aware of this technique, and while we have not yet found a definitive Bronze Age sewn-plank boat in Ireland, the technology was known and being used to repair and modify their boats.’

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The bronze spearhead recovered from the Killbeg vessel.

A further, later, Bronze Age vessel was found near Killbeg. In this case, only the craft’s base remains, but within the boat the team found a socketed bronze spearhead — containing fragments of wood that were radiocarbon dated to the 9th century BC — as well as a complete spear carved from yew, which lay immediately beside the craft and seems to have fallen out of it as it sank. Indeed, spears have proven to be a common feature of several of the logboats: two iron spearheads were also recovered from the 11th-century AD wreck, while a vessel found near Rabbit Island produced four. This latter craft is as yet undated, though the style of the spears suggests that an Iron Age date might not be far off the mark.

The presence of these weapons could indicate that the boats sank while on active service, perhaps patrolling the waters or setting out to raid other lakeside settlements, Karl suggests. Their loss could have been caused by something as simple as everyday wear and tear, he said, although spears are sometimes associated with wrecks where a vessel at the end of its life has been ritually ‘killed’. Unlike the Must Farm logboats, whose back plates were deliberately removed to scuttle them, examination of the Lough Corrib examples has not yet revealed definitive evidence of deliberate sinking.

Medieval masterpiece

The logboat that gives the clearest insights into its construction is the 11th-century AD vessel, dubbed the ‘Carrowmoreknock boat’ after the townland nearest to its findspot. This craft is remarkably well preserved, its sides rising almost to full height around over three quarters of the hull, while four of its five thwarts — seats made from planks — are still in place. Unlike its Bronze Age brethren, this logboat was not paddled, but rowed, as evidenced by the remains of four pairs of thole-pin holes, which would have housed the craft’s oars. From this, we can deduce a little more about the boat’s purpose. With five seats, but only four sets of oarholes, someone was clearly not pulling their weight. Was this the personal transport of a local chieftain?

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The spaces where the Carrowmoreknock boat’s rowers would have sat can still be clearly seen, with most of its thwarts (plank seats) still in place.

‘This is probably among the best-preserved logboats ever found in Britain and Ireland, designed for travelling around the lake at speed,’ Karl said. ‘It is just beautifully crafted, probably made for a high-status individual.’

The care lavished on the boat goes beyond its sleek construction: its owner was evidently keen that any repairs incurred during its working life should not detract from its elegant appearance. At some point, it had sprung a leak through a natural knothole in the wood, which a skilled craftsman patched with a sliver of wood carefully whittled into shape and nailed in place.

‘The repairs we can see on the Bronze Age logboats are purely functional, even crude,’ said Karl. ‘But this patch is an example of excellent workmanship. Clearly people were proud of how the boat looked, and wanted it to remain beautiful.’

Cutting-edge weaponry

As for who crewed the logboat, the discovery of a miniature armoury of weapons inside the boat, including three battleaxes, an iron work-axe, two iron spearheads, and a curious piece of metal provisionally interpreted as a copper-alloy dagger pommel, suggests that rowing was not their only job: these were also warriors.

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Shown after conservation by specialists at the National Museum of Ireland, who restored their handles from fragments preserved by the muddy lakebed, the Carrowmoreknock battleaxes were formidable weapons.

The axes in particular are formidable weapons, with one blade so large that its owner would likely have needed both hands to wield it effectively. In another testament to the preservative properties of the lakebed silt, sections of all three  axes’ cherrywood handles have also survived, and the complete haft of the largest axe is 80cm long. These are classic Viking-style weapons, Karl says, though by the 11th century they are more likely to have been in the hands of Irish warriors than Norse raiders.

‘When the Vikings arrived in Ireland, their battleaxes quickly became the weapon of choice for many local warriors, who swiftly became very proficient in their use,’ he said. ‘There are many battles between the Vikings and the Irish documented in Medieval sources — the Battle of Clontarf, in 1014, is a classic example — where both sides are using axes. By the end of the 12th century, the chronicler Gerald of Wales is also writing about Irish warriors wielding axes with deadly effect against Anglo-Norman knights.’

The Lough Corrib axes may well bear the scars of combat: one blade displays a cut-mark where it could have been parried by another weapon, while notches are present on the handles of all three — although it is not yet clear whether these represent damage or decoration. Study of the axes has been put on hold while they are displayed in an exhibition at the National Museum of Ireland, marking the 1,000th anniversary of the Battle of Clontarf, but the Unit hope to analyse the weapons in more detail when the exhibition closes at the end of this year. The National Museum has co-operated with the National Monuments Service throughout the investigation, committing to take responsibility for the care and conservation of any artefacts that may be recovered from the Lough.

Looking ahead

Further research is also planned for the boats themselves. The team hope to establish firm dates for the rest of the vessels, and to return to Lough Corrib in early summer to investigate other potential wreck-sites and determine which, if any, boats should be raised. Karl is particularly eager to shed light on a cluster of six logboats submerged at the narrowest point of the lake, where the shores are just 750m apart. Could this concentration represent an important ferrying-point or mark the boundary between two tribal territories; if so, when was it in use? Future radiocarbon dating should help to provide the answer.

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The Rinnaknock boat is the only one of the Lough Corrib boats to be raised to the surface so far, as its position left it vulnerable to modern water traffic. It is yet to be radiocarbon dated but, due to its shorter length than the demonstrably prehistoric boats, it is thought to be younger in date. It has since been resubmerged in a safer position.

Establishing dates for all the logboats could also settle the question of whether there is a link between age and length. The demonstrably prehistoric vessels are all upwards of 8-9m in length, some considerably more, and at 6m  long the Medieval logboat also boasts impressive  dimensions. Those suspected of being more modern are much shorter, however, coming in at closer to 3m long.

‘We wonder if this is because the large oak forests that dominated much of Ireland throughout Antiquity were gradually depleted, and the older, taller trees ran out,’ Karl said. ‘If later boat-builders simply did not have access to these longer timbers, it could explain why boats gradually got shorter — though that is currently just a theory. There are still a lot of questions to answer about the Lough Corrib boats — I’m really looking forward to more dating results coming in.


This article appeared in issue 292 of  Current Archaeology.

 

 

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