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.

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 auspicious 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

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.

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 — the muddy lakebed proved more challenging. It is, however, 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.

Sewn planks and spearheads

The well-preserved vessel also reveals traces of Bronze Age construction techniques: 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.

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’.

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?

‘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.’

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.

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.’

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.

This is an extract, but you can read the whole article in Current Archaeology 292.

All images copyright National Monuments Service, unless otherwise stated.

Further information

The exhibition Clontarf 1014: Brian Boru and the Battle for Dublin, which includes the Lough Corrib battleaxes, will run at the National Museum of Ireland until the end of the year. For more information, visit www.museum.ie/en/exhibition/clontarf-1014.aspx

You can find out more about the work of the Underwater Archaeology Unit at http://www.archaeology.ie/UnderwaterArchaeology

The logboats are protected under Irish law, and a licence from the Department of Arts, Heritage, and the Gaeltacht is required to dive any of the discovery sites.