Some Observations on the Strength of Viking Ship Rudders

Technical papers which attempt to analyse historic and ancient ship structures using modern techniques appear only spasmodically in today’s learned engineering journals. There could be many good reasons for this; the lack of commercial incentives, the paucity of accurate engineering data and perhaps a certain reluctance to cross into an area which is rightly the province of the nautical archaeologist. This, in the author’s view is a pity since simplified analytical techniques of the type routinely used in design offices can offer useful cost-effective insights into the physical behaviour of historic ships and craft, without endangering the physical reconstruction or its crew. In addition as the input data are often only loosely defined, less sophisticated methods are ideal for conducting “data-sensitivity” investigations. One such paper (Loscombe, 2022) described efforts to apply modern local and global structural design methods to Viking-age ships with a view to establishing plausible operational factors of safety for comparison with modern requirements. This follow-up contribution continues with the theme by focusing on the rudder. Rudder failure can endanger any ship, ancient, medieval or modern but the Viking ship rudder has a number of structural features not found on modern vessels which invite retrospective stress analyses. One component in particular, the lower bearing in modern terminology, appears to have a very short operational life, measured in days rather than years as is the expectation for today’s marine vehicles and hence the Viking ship rudder is a good candidate for such simplified numerical analyses.