The reconstruction of Viking Age and Early Medieval ship’s sails has proved a particular challenge for the Viking Ship Museum, as there are but few traces preserved in the archaeological record. It is therefore necessary to draw on information from comparable finds and ethnological evidence. Below is a summary of the general questions concerning the reconstruction of sail and rigging:

The Viking ships’ square sail was, in size and shape, developed together with the individual hull size and type of ship. The central crucial factor is the elementary balance between hull, sail and rudder when sailing against the wind, i.e. sailing close-hauled.
If the sail is too broad relative to the hull and the shape of the hull, the ship seeks away from the wind – it has lee helm, and cannot tack against the wind. If the sail is too narrow, the ship turns into the wind without the rudder being able to prevent this – it has weather helm. If this is not corrected, the ship is dangerous to sail – in fact it is useless as a sailing vessel.

If the sail is too low, the ship will sail too slowly and it will first sail properly when the wind is very strong. If the sail, and with it the mast, is too high, the load is too great and it is necessary to reef the sail too early.

Further to all this, it is vital that the individual types of ship are ballasted and loaded correctly. In the successors to the Viking ships, the North European square-rigged boats, identical conditions can be traced. Here, there were regulations for the dimensions of the mast, sail and rudder for the individual boat types. There are a number of finds of rigging details, for example blocks, shroud pins, mast fragments, yard etc. from the Viking period and the Middle Ages. They show little variation in principle and execution throughout this time, and also relative to the last Nordic square-rigged boats from the early 20th century.

In combination with oral tradition, it is therefore possible to produce rigging for the individual ship finds within very narrow constrains. 
The Museum's weaver Anna Nørgaard, has begun working on a sail of flax for the Gislinge boat. 

Weaving a sail of flax for the Gislinge Boat

Flax has been used to produce textiles in Scandinavia since the Iron Age. Transforming the plant into fibres that can be spun, and then woven, is a long and complex process.

  • The plant stems are pulled by hand, so the end of the stem remains intact
  • The plants are rippled (combed) to remove the seeds from the stems
  • The flax is then retted (submerged in water for 1-2 weeks, or laid on a meadow for 4-8 weeks), to loosen the fibres from the pith
  • The stalks must dry out before being broken to separate the woody pith from the fibres
  • The fibres are then scutched (beaten) to remove the small fragments of pith
  • Lastly, a hackle (comb with long iron teeth) is used to remove the final impurities and straighten the fibres
  • The flax is now ready to be spun

This is the first time the Museum has produced a handwoven sail from flax. No sails made from flax have yet been found from the Iron or Viking Ages. However, other archaeological evidence demonstrates that flax was grown and processed.

The sail is made up of five long panels, which will be sewn together to make the finished 10m2 sail. The Museum’s weaver will produce one of the panels; the other four panels are being woven by weavers from the Institute for the Blind and Partially Sighted. When complete, the sail will be impregnated to help prevent rot.