When the Officers on the Watch (OOW) will decide on overtaking another vessel at night time, the OOW relies solely on visual information from “a white light (stern light).” Therefore, the “stern light” is a very important factor in overtaking situations. The OOW can recognize another vessel in front of their own vessel by identifying the “stern light.” The stern light’s arc on the horizon is 135 degrees, and fixed so as to show the light 67.5 degrees from right aft on each side of the vessel, which can make it difficult for the OOW to estimate the proceeding direction of another vessel. Previous research pointed out that “poor surveillance of another vessel” was the most common cause in collision cases related to stern light visual confirmation. Therefore, it is most important that the OOW will be estimate the proceeding direction of other vessel to be overtaken.
This paper focuses on an analysis of a questionnaire survey for pilots and coast guard officers. The contents of the questionnaire survey investigate ① “When you look the another vessel’s stern light by naked eyes in overtaking situation at the night time, how do you think about the proceeding direction of the another vessel?” ② “When you look another vessel’s proposal new auxiliary stern light by naked eyes in overtaking situation at the night time, how do you think about the proceeding direction of the another vessel?” ③ considered the effect and the issue of proposal new auxiliary stern light.
The results suggest that ①Responders had not been able to estimate the proceeding direction of the another vessel. Furthermore, the estimated proceeding direction of the another vessel were various and big difference. ②In the proposal new auxiliary stern light case, responders had been able to estimate the proceeding direction of the another vessel. In addition, the proposal new auxiliary stern light was possible to reduce the width of the estimated proceeding direction of the another vessel. ③The proposal new auxiliary stern light was effective for estimating the proceeding direction of the another vessel, however, it had a possibility of making a misunderstanding another navigational light (ex. Small boat).
After a background review of this issue, this paper will analyze the data from the questionnaire results, and finally discuss conclusions and offer some suggestions for measures to correct any problems, as well as directions for future research.
This study examined how two factors of ship navigation, multitasking and vibration, degrade visual attention. In Experiments 1 and 2, 11 and 20 participants, respectively, viewed a 1-min ship-navigation video and performed two tasks: one detecting as quickly as possible a small target presented for 0.3 sec in the video, and the other carrying out the detection task while performing mental calculations. In Experiment 1, the participant’s chair was stationary, and in Experiment 2, it pitched or rolled to induce vibration (or body sway), as if on a ship. Reaction time (RT) to the target and rate of oversight (RO) were indices of visual attention. In Experiment 1, the type of task affected RT but not RO. In Experiment 2, the task effect diminished for RT but was observed for RO. Furthermore, roll and pitch affected RT but not RO. The results suggest that inclusion of mental calculation and simulated ship motion can degrade visual attention, and the degree of the degradation differs depending on the index used for assessment. We discuss the implication of the results for marine accidents.
The aim of our study is to develop a mental workload monitoring system to be adopted in ship handling simulator education. The mental workload monitoring system immediately evaluates and shows the mental workload responses of bridge team mates. In addition, it enables us to immediately instruct the beginners on professional maneuvering, which is why the mental workload monitoring system is effective for simulator education and attributes to safe navigation. To measure the mental workload we chose the heart rate variability which is known as one of the indices of mental workload. In this research, mental workload was measured by using two devices, a heart rate monitor and a patch type device. The patch type device is essential for the mental workload monitoring system because it immediately shows the mental workload of subjects. We needed to use the heart rate monitor to substitute for the patch type device because it is still under development. In this study, we compared and evaluated the mental workload responses between the beginners and professionals to ship handling events in simulators by mental workload monitoring system, and stored the data. This research presents the usefulness of mental workload monitoring system and finds some problems with the devices to develop that system.
Hydrogen fuel-cells produced using surplus electric power and industrial by-products have desired energy efficiency and do not produce discharges containing atmospheric toxic substances such as carbon dioxide and NOx. The development of a vehicle and a vessel that can transport hydrogen fuel cells is considered at present. In the case of the vessel, a decrease in the underwater noise is an additional advantage. In this study, we considered the differences between the amplitude and frequency characteristics of underwater noise of a fuel-cell, small diesel, and aquaculture working vessels. Recordings were acquired based on four speed condition of 4, 8, 10, and 14 knots. The radiated underwater noise spectrum levels (RNL, dB re 1μPa/√Hz at 1 m) were calculated from the recording sounds. The RNLs of the fuel-cell vessel at every speed were lower than those of the other vessels and less than 300 Hz of the sound frequency. In contrast, the RNL of the aquaculture working vessel exhibited some peaks for low frequencies less than 300 Hz, and it was thought that engine noise had a considerable influence on this behavior.