The Development of the Rudder: A Technological Tale

The introduction of the centerline rudder, first on the ships of northern Europe and then on Mediterranean vessels, was a technological development of great importance. The usual interpretation has been that a superior technology, a single rudder hung at the center of the stern of a sailing vessel, developed in the Baltic and North Sea and spread to the Mediterranean rather quickly at the end of the thirteenth or the beginning of the fourteenth century. Its technological superiority has been considered self-evident; after all, the centerline rudder is virtually universal on boats and ships of all types, even today. That the technological transfer from north to south was sudden seemed almost equally self-evident. The fourteenth-century Florentine chronicler Giovanni Villani’s entry for 1304 seems to imply that Gascon pirates introduced a new ship type, the cog, that used a centerline rudder and that it was immediately adopted by the leading seafaring cities of Italy. Even if one did not accept Villani’s account literally, it seemed to fit well with other evidence of a sudden cross-fertilization between the northern and southern shipbuilding traditions beginning in the fourteenth century and leading quickly to the development of the full-rigged ship in the fifteenth. A clear case of interaction apparently exists between two traditional technologies, leading to the breaking of a conceptual logjam and opening the way for innovation on a grand scale.

Lawrence Mott’s “technological tale” shows the value of questioning assumptions and applying careful analysis even to evidence long available. Traditional assumptions about the introduction of the centerline rudder prove not so much wrong as incomplete, without nuance, and simplistic. If rudders mounted on either side of the stern quarter of a vessel were manifestations of an inadequate technology, why did they persist for over two millennia in the Mediterranean? Mott demonstrates through careful analysis of primarily iconographic evidence that the quarter rudder was not a static technology, but that its design changed and evolved over time. With mathematical and experimental analysis, supported by testimony regarding the use of quarter rudders on modern Indonesian pinisi, he demonstrates that, far from being an inferior technology, quarter rudders can be highly efficient both mechanically and economically. Centerline rudders (Mott prefers the term “pintle and gudgeon rudder” as more precise and descriptive of the essential technology involved) can be less efficient, more expensive, and harder to repair at sea than quarter rudders. At this point the question of technological transformation becomes a much more interesting one. No longer can we be confident that this is a case of a self-evidently superior technology replacing an outdated and inferior one. The task becomes one of explaining how a technology that in its early form was decidedly less attractive on most counts than the older, more highly developed one gets a foothold that allows it to develop and eventually demonstrate its advantages.

The story of this development is at the core of Mott’s book. He shows that the pintle and gudgeon rudder is truly effective only as a part of an ensemble of technologies that work together. The rudder only became truly efficient when changes in hull forms and rigging also took place. In essence, he explains how the cross-fertilization between northern and southern technologies operated. Not only was the adoption of the pintle and gudgeon rudder a question of breaking down conceptual barriers, it also required the true application of knowledge contained in the minds and hands of the masters of each tradition to specific problems. The single quarter rudder used in northern waters was not efficient for large vessels. Thus, as ships grew larger, northern shipwrights were faced with a problem that found its solution in a new ship type, the cog, which had a straight stern post with a pintle and gudgeon rudder hung on it. The rounded sterns of the southern tradition posed both mechanical and...