Roskilde, Denmark ? On the skipper’s command, deckhands haul in tarred ropes to lower the flax sail. Oars splash into the water. The crew, grimacing with strain, pull with steady strokes sending the sleek Viking longship gliding through the fjord.

The Sea Stallion of Glendalough sails Saturday in the Roskilde fjord in eastern Denmark. The crew of the reconstructed Viking ship will sail across the North Sea from Denmark to Dublin, which was founded by Vikings in the ninth century.

A thousands years ago, the curved-prow warship might have spewed out hordes of bloodthirsty Norsemen ready to pillage and burn.

This time, the spoils are adventure rather than plunder.

The Sea Stallion of Glendalough is billed as the world’s biggest and most ambitious Viking ship reconstruction, modeled after a warship excavated in 1962 from the Roskilde fjord after being buried in the seabed for nearly 950 years.

Volunteers are preparing it for a journey across the legendary Viking waters of the North Sea – leaving Roskilde in eastern Denmark on July 1 and sailing 1,200 miles to Dublin, which was founded by Vikings in the ninth century.

“It’s like a banana boat. It moves like a snake,” crew member Preben Rather Soerensen, 42, said after a recent test sail in the Roskilde fjord.

The crew will explore the challenges of spending seven weeks in an open vessel with no shelter from crashing waves, whipping wind and drenching rain. Working in four-hour shifts, the history buffs and sailing enthusiasts will have to steer the 100-foot ship through treacherous waters with a minimum of sleep, comfort and privacy – just as the Vikings did.

“They must have been incredibly tough to do what they did,” said 24-year-old crew member Triona Nicholl, an archaeologist from Dublin. “We all have waterproof gear. We have radios and life jackets and all the stuff. They must have been hardier people.”

The Vikings turned to the stars and their ancient Norse gods for help as they navigated across the open sea, reaching as far as Iceland and North America. Many died in the hostile waters of the North Atlantic.

This crew puts their faith in modern technology: a GPS satellite navigation system and radar. They wear baseball caps and wind-breakers rather than helmets and chain mail shirts. Mobile phones are allowed, but no battle axes.

Nevertheless, the crew is likely to feel they have been transported back a millennium when the voyage begins, although it will be accompanied by a modern support vessel with medical and rescue experts.

The Viking boat has the curved hull and single square sail that typified Norse longships, which were designed to sail on both open seas and rivers.

Using replicas of Viking era tools – chisels, knives, spoon bits and axes – craftsmen built the 8.25-ton Sea Stallion using 5,250 cubic feet of oak and 7,000 hand-forged iron rivets.

“Within a certain framework, we knew how they built the ship and how the missing parts should be,” said Erik Andersen, 68, who designed the replica. “The only guesswork was the color of the ship and the sail.”

The builders settled for a brown hull and a red-and-yellow sail, drawing inspiration from the famed Bayeux tapestry in France, which depicts the 11th century Norman conquest of England. The Normans were descendants of Viking settlers in northwestern France.