Calculations without math: “Smart instruments” and the transposition of complex shapes in the wooden boat workshop

This paper considers a historical boat building practice in light of Runeson’s (Scan J Psychol 18:172–179, 1977) concept of ‘smart instruments’, tools that exploit particular features of situated processes to aid their users in complex cognitive operations. The key example here is that of the ‘spiling stick,’ a flexible baton used to determine the two-dimensional shape of board stock that will eventually twist to fit a three-dimensional position on the hull of a ship. The authors illustrate the complexity of the cognitive operation carried out by the ‘coupled system’ (Clark and Chalmers in Analysis 58:7–19, 1998) of boat builder and spiling stick by performing a comparable operation solely with advanced math and physics, tools unavailable for most of the history of wooden boat building. The notion of a ‘smart instrument’ is then discussed in more detail as the authors argue that spiling need not be seen as a mathematical operation supported by material aids, but rather that math and materials provide equal routes for comparable cognitive work.