Analysing Ancient (Viking) Longship Structures

The Nordic longships of the 9th to 11th Centuries were perhaps the preeminent fast assault ships of the period. Modern engineering analytical tools have been employed from time to time to investigate their stability, performance and structural characteristics.  The latter is perhaps the most challenging, since the physical problem is that of a hydro-elastic body in rough seas, constructed of a material with highly variable mechanical properties, fastened together by rivets, treenails, nails, spikes, lashings and wedges of uncertain joint efficiency. The corresponding analysis is potentially considerably more complex than the ‘linked-chain’ method commonly employed in modern design offices to establish acceptable scantlings, i.e. classification society rule loads and criteria together with reliable published material property data which are the essential inputs to scantling formulae/finite element analyses (FEA).  This paper outlines one small craft naval architect’s view of the issues involved in applying the standard structural design method to the analysis of a ship type which is radically different from modern craft and in so doing identify issues which may be of interest to modern naval architects analysing unconventional lightweight structures.