state since individuals' circadian rhythm and sleep patterns can have a big impact in the MF state during specific periods of the day. Before the experiment we made sure the participants were aware of all aspects of the simulated task and data collection and their informed consent was obtained. We also ensured that our experiment closely followed the guidelines of the Declaration of Helsinki. Results and Discussion Fig. 4. Perceived KSS level for each test subject, from the beginning to the end of the experiment. During the multi-subject and multi-task experiments we included different navigation exercises, with varying distances, duration, and vessel sizes. In each exercise we had between two and three participants in the bridge at the same time. There was always a pilot and a navigator, and in the cases in which we had three participants, the third one was responsible for communicating with other vessels and the control center. In each case, we monitored either the pilot or the navigator. The Fig. 5. Results for each test subject, showing MF level distribution, MF score and KSS levels. 86 IEEE Instrumentation & Measurement Magazine June 2021