Such 'dragons' were constructed without plans and the design was passed down from father to son. The Vikings were able to mount fast, surprise attacks with these longships, but could retreat just as rapidly in the face of massive resistance. This type of ship had an approximately 20 m long displacement hull of overlapping wooden plank construction. It was held together with metal rivets.
All of the wooden parts were split from tree trunks using axes and wedges. The Viking warships were rowing boats that, with the right wind conditions, could also be sailed with a rectangular sail and folding mast.