Decision making and strategies in an interaction situation: Collision avoidance at sea

This paper aims at analysing decisions which are actually made by watch officers onboard ferries in the Dover Strait. More precisely, it aims at characterizing the generic situations in which several courses of actions are available and identifying the strategy underlying an action choice. Relying on the RPD model of Klein [Klein, G. (1997). The recognition-primed decision (RPD) model: Looking back, looking forward. In C. E. Zsambok & G. Klein (Eds.), Naturalistic decision making (pp. 285–292). Mahwah: Lawrence Erlbaum Associates], it points out the critical cues, the goals of actors and the rules they use.Two sets of data were processed: motions of vessels observed from the vessel traffic system and verbal protocols recorded onboard a ferry with three watch officers.Logistic regression models show that different types of ships do not act in the same way: the slowest vessels tend to keep their course and speed, even if they have to move. The faster cargo ships such as ferries alter their course in compliance with the regulations. In some situations, a ferry may nevertheless follow informal rules. Onboard a ‘give way’ ferry, a watch officer may – in some conditions – alter his course to port rather than to starboard to reduce the course alteration and the loss of time. On board the ‘stand on’ vessel, he may perform an action in order to master the situation, even if the rule requires him to keep his course and speed.