The Tides of the Zodiac MK VI HD: Comparing the Usability of Inflatable Boats for Seaborne Operations

Abstract

OCCUPATIONAL APPLICATIONSThis user-centered study compared the usability of old and new models of an inflatable boat during a multi-day high-pressure military exercise. Participants represented the entire population of Special Operations soldiers who were experienced with both models, providing assessments on the effectiveness, efficiency, and user satisfaction of the boats and their central console, one of the main components that was updated on the new model. The new model was rated as significantly more usable in terms of effectiveness, efficiency, and user satisfaction. Although the response to the new model was overwhelmingly positive, follow-up interviews identified specific problems associated with changes introduced with the new model. These included: (a) visibility problems with the windshield, caused by the accumulation of spray and salt; (b) increased difficulty of moving/installing the central console, due to the doubling of its weight; and (c) fuel uptake issues, resulting from the new flexible fuel bladder.TECHNICAL ABSTRACTBackground: The military has been used as a test bed for human-system performance for decades. The present study used the upgrade of the Zodiac MK VI Heavy-duty (Zodiac MK VI HD) inflatable boat, issued to a platoon of a Special Operation Engineers, as a unique opportunity to compare the old and new model’s usability during multi-day seaborne exercises. Purpose: To compare the old and new Zodiac MK VI HD (with its upgraded central console) in terms of effectiveness, efficiency, and user satisfaction, by involving expert users in their most extreme context of use. The assessment implied both a formal empirical measurement that enabled a data-driven comparison between both boat types, and an interview-based problem discovery phase to identify future design improvements. Method: Using a customized questionnaire based on the ISO 9241 standard, a repeated-measures field study was completed using all Special Operation Engineers (N = 17), using both Zodiac MK VI HD types interchangeably, in their most extreme environment of use. Remaining design flaws were explored using open-ended survey questions and interviews immediately following usage. Results: The new Zodiac MK VI HD, including all upgrades (e.g., console, digital controls, LED-based displays) was rated significantly higher in terms of effectiveness, efficiency, and user satisfaction. Additionally, problem discovery efforts revealed that design issues remained with the opaque windshield during seaborne operations, weight of the console, flexible fuel bladder, and power loss that affected the console’s digital speed and position display. Conclusions: These results highlight the importance of comparative usability research and problem discovery, directly involving end-users in high-pressure operational circumstances. Broadening its inferences to many other high-reliability occupations (e.g., law enforcement, fire fighters, and medical first responders), effectiveness, efficiency, satisfaction, ease of maintenance, and feelings of increased safety are important considerations, because they affect the performance of human-machine systems.