Modern heavy weather sails are made of Kevlar – or something like it. Studies in Norway have indicated that the ninth century viking sailors used sails made mainly of wool – maybe with some hemp fibres. This makes absolute sense; arable land in the region would have been much too valuable to commit to the growing of flax and hemp on a large scale, whereas Amy Lightfoot of The Tommervik Textile Trust reckons 1 ha of rough pastoral heathland would produce, in a good year, enough wool for 1 sq.m of sailcloth. A large heavy-weather longship would therefore demand an area of heathland of about 110 rugby football pitches – which would seem entirely feasible.
However, she also calculates (having actually done the job herself) that the making of a heavy weather sail from sheep wool would take nine shepherd/spinner/weaver/sailmaker years of work and, since the risks of a failure in the cloth were somewhat severe, the process of weaving and sailmaking demanded highly skilled women – since weaving tools have been consistently found in women’s graves.
What I find intriguing is that there is very little evidence of Scandinavian ships powered by sails before AD 800 (Jan Bill, Curator of the Ship Museum Oslo). Before that date, they were rowed.
The first ship excavated with a mast and sail was the Oseberg ship, which was constructed in about 775. And the first attack by Danes in longships began in the British Isles in 787 – according to the Anglo-Saxon Chronicle. So it does appear that the development of sufficiently strong woollen sails was the key factor in launching the adventures of the Scandinavians.
Now buried in the Oseberg ship was not a king, but a queen. And is it not fascinating to speculate that she might have been the inventor of the goose-eye or diamond twill that gave the resistance to tearing in the cloth?
www.academia.edu. Proceedings of the 10th Nordic TAG Conference 2009.The introduction of sails to Scandinavia: Raw materials, labour and land, Lise Bender Jørgensen, Norwegian University of Science & Technology
The Viking World (Routledge Worlds) 2008: Amazon.co.uk. https://www.amazon.co.uk/Viking-World-Routledge-Worlds/dp/0415692628