Sunday, June 12, 2016

Technology coevolution

From The Development of the Rudder, 100-1600 A.D.: A Technological Tale by Lawrence V. Mott.

From the abstract:
The one instrument which all ships have in common is a rudder. Until the 13th century A.D., the primary instrument used to control ships was the quarter-rudder system. Unlike the present-day rudder which is mounted on the stern, quarter-rudders were mounted on the sides of ships towards the stern.

The Mediterranean quarter-rudder was an inherently simple device and had only three basic requirements for mounting. This simplicity allowed shipwrights to adapt the quarter-rudder for use on a wide variety of vessels. Not only did the quarter-rudder concept permit the use of this type of rudder on different kinds of ships, but the basic system was also sufficiently flexible to evolve, thus insuring its continued use through the Middle Ages. As the methods for mounting the quarter-rudder changed, so did the design of the rudders themselves. The traditional Greco-Roman rudder gave way to the more efficient medieval rudder, which enhanced the overall performance of the quarter-rudder system.

A unique quarter-rudder system indigenous to northern Europe had also evolved, but unlike its southern counterpart, this system was rather inflexible. Northern shipwrights found that their system could not be adapted to the new ship designs which were continually increasing in size. This inability of northern shipwrights to adapt their system to larger ships created a technological crisis which forced them to look for a new device. The result was a rudder mounted on the stern by a hinge device called the pintle-and-gudgeon. Because this new device had several deficiencies, it did not immediately replace the Mediterranean quarter-rudder. Only after a significant change in hull design, and the appearance of the full-rigged ship, did the pintle-and-gudgeon rudder finally supplant the quarter-rudder.

The history of the quarter-rudder shows that technologies which are flexible are the ones which tend to survive the longest, while that of the pintle-and-gudgeon system is a classic example of a technology having to await the development of other before it can realize its full potential. The continued use of the quarter-rudder, despite some inherent drawbacks, demonstrates that there is a human tendency to try to modify existing technologies to their extremes, instead of immediately searching for more radical solutions to a given problem.
The core problem faced by northern shipwrights was that as their ships became larger, the traditional Mediterranean quarter-rudder became less effective. The pintle-and-gudgeon rudder mounted on the stern centerline of the ship was a good solution to the decreasing effectiveness of quarter-rudders on larger ships but brought its own shortcomings. The triumph of the pintle-and-gudgeon rudder, which became the dominant solution, only came about through the coevolution of sails, rigging, and hull shape to optimize the outcome for steering control, size, speed, etc.

The central observation is that the pintle-and-gudgeon rudder solution did not spring to life as an obvious solution. It became dominant only through coevolution.

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