A team of archaeologists has recreated the heather ale drunk by marauding Vikings to boost their ferocity in battle.

Galway archaeologists Billy Quinn and Nigel Malcolm and businessman Declan Moore have been involved in their "great experiment" for the past three years, sampling Bronze Age brews and unearthing Ireland's ancient recipes and beer-making traditions.

The intrepid trio have just brewed their first heather ale using a recipe believed to date back to the 8th century AD.

'Bheoir Lochlannachis' is made from heather and barley; and instead of hops, which only became common in brewing in the 9th century, the herb bog myrtle is used to add flavour and preserve the potion.

Some sources believe the word 'ale' comes directly from the Viking word 'aul', and, according to legend, Norse invaders downed substantial quantities of the heather brew to whip up their battle frenzy.

The trio brewed the Scandinavian ale with barley from the Oslo Hotel Microbrewery in Salthill. The heather was gathered at Maumeen Lake in Connemara.

"We're using a recipe that was recorded in the 'Ulster Journal of Archaeology' in 1859," explained Mr Moore, MD of the Moore Group, an environmental consultancy firm. "It dates back, we would estimate, to the early Christian and Viking period."

Unlike the Moore Group's previous beer experiment, which involved using a prehistoric cooking pit heated by stones, the Viking beer was heated in a large pot and is now fermenting.

When the brew is ready, the team plans a private beer-tasting party next month. "We're going to produce around 150 litres and by the time that's filtered and sieved, there'll be 100 litres -- plenty to go around," said Mr Moore, while Mr Malcolm, general manager of Moore Group, said the finished product was eagerly anticipated.

This is not the trio's first foray into bygone brewing techniques. In 2007, the team produced a Bronze Age brew using a prehistoric cooking pit, which overturned the belief that brewing was only practised here from the 6th century onwards.