Vikings. Beyond the Legend.

Decking was very simple on warships, where oarsmen sat along the crossbeams.  The expression víka sjóvar tells us that a man worked the oar with a thousand strokes, or for about two hours, before he could be released.  Describe the challenge of rowing and how the rower kept going on a particularly challenging crossing. 
Image:  www.hurstwic.org/history/articles/manufacturing/text/norse_ships.htm