A replica Viking ship trying to sail across the North Sea has been forced by unfavourable winds to accept a tow.
The Sea Stallion set out on Monday from Norway bound for Scotland but struggled to make headway on a calm sea.
The passage was being undertaken as part of a "living archaeology" project that aims to understand better the seamanship of early Norsemen.
Project organisers from the Viking Ship Museum in Roskilde, Denmark, said time pressures had forced their hand.
They told the BBC - which is following the Sea Stallion for a Timewatch film to be broadcast later this year - that their research schedule could not simulate every aspect of Viking behaviour.
"If we went back and hid in a Norwegian fjord - like the Vikings would have done - then we would be there for a week or two. Now, we'll take a tow to Orkney and hope for good sailing there," a disappointed skipper, Carsten Hvid, explained.
The ship's volunteer crew has already faced severe weather conditions on the journey from Denmark to Norway, with several individuals being taken off the Sea Stallion temporarily because they were showing the early signs of hypothermia.
The crew had rowed out of the port of Eigersund, on the Norwegian coast, hoping to pick up a good breeze - but it never came. The decision to abandon the sail and take a tow to Kirkwall, on Orkney, was taken after weather forecasters told the crew they could find themselves stuck in the middle of the North Sea just as fierce gales blew up.
A rope was then slung across from the support ship, Cable One, which motored to Scotland. They were expected at Kirkwall on Tuesday afternoon.
The North Sea segment is part of a much longer, 1,000-mile round trip from Denmark to Ireland over seven weeks. The research project is intended to gain insight into how Vikings used their ships to make great sea journeys.
"As a consequence of the decision of towing the Sea Stallion across the North Sea, this part of the passage has now been cancelled in the research plan for 2007," said Viking Ship Museum director Tinna Damgard-Sorensen.
"Primarily, this affects the part of the research programme dealing with the trial voyage itself - the possibility of estimating the travel speed across the North Sea, and the possibility of evaluating the functions and the logistics on board during a long crossing. These aspects will be reassumed during the voyage from Ireland to Denmark in 2008," the museum official told the project website.
The original Sea Stallion was made in 1042, and is believed to have taken part in clashes between the Anglo-Saxons and Normans in 1050-1060, when many Danish Vikings lived in Ireland.
The boat sank in the Roskilde fjord at the end of the 11th Century, while defending the country's coast from Norwegian Vikings.
The replica was constructed from about 300 oak trees and using 7,000 iron nails and rivets.
At 30m (100ft) in length, the Sea Stallion is said to be the world's largest reconstructed Viking vessel.
The ship hopes to reach Dublin in mid-August.
The ship's crew are writing a weekly diary for the BBC News website. More regular updates and a map of the ship's latest position can be found at BBC History's Viking Voyage website.
THE SEA STALLION FROM GLENDALOUGH
1. The crew of 65 men and women will sleep on the open deck, as the Vikings did, and take turn keeping watch
2. Satellite navigation equipment will make sure the ship stays on course. Vikings had to rely on the position of the sun and stars, the colour and movement of the sea and wind direction
3. Oak planks were cut radially for maximum strength, overlapped and nailed together. Axes and other tools used to make the planks were replicas of those used by the Vikings
4. The sail, mast, rigging and rudder on the original were missing so these have been copied from other finds
5. Shields, vital in battle, were tied over the oarports when the ship was in port
Sources: Viking Ship Museum, Denmark; National Maritime Museum, UK. Photos: Werner Karrasch and Erwan Crouan