On the Last Northern European Large Rowing Vessels
In the region surrounding the Baltic Sea and the North Sea, five iron age rowing boats have been found and excavated near Hjortspring (Denmark), Nydam (Denmark), Sutton-Hoo (England) and Kvalsund (Norway; two boats at the same location). With one exception, these boats were powered by about 20 to 30 rowers and were vessels to transport just those men with little or no capacity for any cargo or passengers. Their approximate ages have been dated ranging from approx. 450 BC to 700 AD. Despite this range of over a thousand years, these five boats feature, technically speaking, many similarities.
Relatively much has been published about these boats from an archeological and historical point of view but little with regards to their technical aspects. This paper is dedicated to a technical appreciation of what amounts to the state of boat design, at least in that region, before the sail-powered and/or cargo-carrying vessels appeared.
Following the introduction in chapter 1, chapter 2 contains a condensation, as it were, of known technical aspects of these five boats gathered from various sources and discusses them from an engineering point of view. This includes, for example, a contemplation of the remarkable fastening of the planks of the hull to the frames by rope lashing in some cases and wooden nails in others. Some kind of cleats that were an integral part of the planks served as the interface between the planks and the frames, leading to a very inefficient use of the wood: Up to 95% of it ended up being planed down. The planks themselves overlapped each other in a clinker-built fashion and were fastened to each other with iron fasteners or, in one case, with rope.
Chapter 3 endeavors to further assess some key technical parameters of these boats. In order to be able to do so, first, a vessel, called “NYDAM-2017” and somewhat representative of the above-mentioned five boats in general and the real Nydam Boat in particular, is specified. That specification is based on technical details known about the individual five boats as well as engineering judgement. On the basis of that specification, then, certain calculations could be and have been performed for “NYDAM-2017” regarding its weight, its draft vs. displacement curve, some of its structural strength aspects and a number of its stability-related parameters. The former imply a robust design, especially from a longitudinal strength point of view; the latter imply that many of these boats are like to have gotten lost due to capsizing.
The brief chapter 4 presents some final thoughts by the author and highlights just how long the Nydam kind of boat design and construction lasted – at least one-thousand years – and how relatively quickly it, then, was superseded by ships powered by wind and, oftentimes, carrying substantial amounts of cargo.
Finally, an appendix contains a list of references, a map indicating where the five boats were found, several illustrations, incl. lines plans for the five boats discussed, and tables with the results of the calculations discussed in chapter 3. The author regrets that the scanning and subsequent PDF conversion has led to a noticeable decrease of the quality of the lines plans relative to their originals.