In order to make a countermeasure for a sea disaster such as the 2011 Tohoku earthquake and tsunami, it is required to reproduce the motions of ship precisely and practically, and the key issue is how to express the tsunami wave forces. Several physical model tests on ship’s behavior and tsunami wave forces, which was a modeled 90,000DWT class coal carrier affected by the Tohoku disaster, had been conducted in two-dimensional water tank during a tsunami bore. The surface elevation, current, motions, mooring loads and tsunami wave forces of the ship had been measured in a following sea. In this paper, a systematic approach to reproducing the ship motions, mooring loads and tsunami wave forces has been investigated by using a numerical simulation method of ship motions.
In the airline industry which handles the same transportation as the shipping industry, the importance of non-technical skills as a required competency for airline pilots is recognized, and the education and training to improve abilities such as cognitive skills, judgment skills, and communication skills has begun. In the shipping industry as well, BRM training was included in STCW the Manila Amendments in 2010, and it began to be required to educate situational awareness. It is necessary to enhance situational awareness to avoid collision with other vessels.
In this study, to analyze the relationship between the situation awareness elements of non-technical skills and the causes of collision accidents, authors created a situation awareness classification sheet on the navigational watch and analyzed which component is related to the accident.
In this paper, authors considered what kind of the education and training should be introduced to enhance situational awareness required for officers in charge of the navigational watch.
As Global Positioning Systems (GPS) have come into widespread use, questions have been raised as to whether traditional geographic and astronomical navigation techniques have a place in today’s world.
In this context, written examinations to obtain the license (seamen's competency certificate) required for seafarers invariably include questions on astronomical calculations necessary for navigation. Students who study navigation at seafarer training institutions are strongly motivated to obtain this license. However, in-class time by itself is not enough for students to master such astronomical calculations, so they also put effort into independent study outside of class hours. In addition, in order to efficiently improve their problem-solving ability, the students need a lot of practice and the capacity for quick corrections. As it now stands, this learning environment is inadequate, and the instructors in charge of the classes are struggling.
Therefore, in this study, teaching materials were developed that allow students to create a large number of practice problems and answers all at once for astronomical calculations. The present study reports on the results of an analysis on the effects that these materials had on the proficiency of current students.
Catamaran type Unmanned Surface Vehicle (USV) has many applications as an autonomous platform in the field of marine engineering, such as collection of marine waste in harbors, support vessels for offshore work, ocean observation platforms, maintenance vessels for offshore wind power generation and so on. The authors have been constructing a tank experiment system and conducting a basic study of control algorithms by simulation with the aim of developing a system necessary for autonomy. As the next step, experiments in the actual sea area are essential for developing a system that autonomously navigates in unknown disturbances. In this paper, we discuss the optimal control algorithm that we designed based on the results of simulations of trajectory tracking control and the outline of the USV system from the viewpoint of constructing experimental system at sea.
Small trawl fishing is an important fishery that supplies a variety of fishery products to the market. The fishing operations are usually carried out in coastal seas. In this study, the authors focused on beam-type small trawl fishing boats in the northern coastal seas of Kyushu. And we conducted a survey about the operating methods and the labor-saving effects by use of fishery machines. By the use of the trawl winch, the shooting net time was shortened compared to the conventional method. Furthermore, applying the OWAS method for the physical burden of skipper, the labor-saving effects are confirmed on net shooting and hauling operations.
The spatiotemporal distribution of tidal currents in Seto Inland Sea (Seto Naikai) is complex and characterized by very strong localized currents. Understanding the actual conditions and generation mechanisms of these currents will contribute to increasing the safety and efficiency of shipping and fisheries operations, as well as monitoring marine driftage in the region. In this study, we compared current information obtained by the Japan Coast Guard with acoustic Doppler current profiler (ADCP) observation results collected by the “Hiroshima-maru”, a training ship of the National Institute of Technology, Hiroshima College, during training voyages in Seto Inland Sea. By comparing and analyzing these data, the accuracy and advantages of each method were verified, and several unique current characteristics were observed in local areas. The ADCP data collected during training voyages were collected along linear transects over short periods during changes in the tides. By collating the data collected over numerous time points and locations on different voyages, we were able to characterize the spatiotemporal characteristics of the currents of the entire area.
The sea stations (“UMI no EKI”) are facilities that provide visitor berths, such as pleasure boats and yachts, to users visiting ports. As of August 2021, 177 stations are registered with the Ministry of Land, Infrastructure, Transport and Tourism, Japan. One of the functions of a sea station (“UMI no EKI”) is to serve as a base for disaster prevention and rescue in the event of a disaster. During the July 2018 heavy rains, the “Kure Sea Station” (“KURE UMI no EKI”) in Kure City, Hiroshima Prefecture, was used as a transportation base. In the event of a future disaster, it is expected to be of great utility. In this study, a questionnaire survey of sea stations (“UMI no EKI”) was conducted throughout Japan to learn about the current state of their disaster prevention functions and to identify issues for disaster. As a result, 82 stations responded, twenty-nine stations (35.4%) indicated that they had established cooperative relationships with municipalities and local communities, and their most common roles were marine rescue, evacuation shelters, and supply support. Approximately 74.4% of the respondents indicated that marine stations could be used as bases for transporting small vessels in the event of a disaster, implying that marine stations could be used as a base for transportation in the event of a disaster. Approximately 41.0% of the respondents indicated that marine stations could be used as transportation bases in the event of a disaster had a dispatch route for small vessels. Therefore, considering whether using marine stations during disasters and secure dispatch routes is possible is important.
One of the causes of accidents at sea involving small boat is not enough lookout. However, there have been few studies on behavior of boat’s operator such as lookout and safety checks on boat.
This research had a purpose which was to compare the behaviors of beginner and expert operators when maneuvering a boat and to reveal the differences between them. We conducted a maneuvering experiment of the operator’s behavior on straight line and altering course on 14 operators. As a result, we found that there was no difference in the number and duration of gaze in straight line course, and expert operators had many gazing time and duration for the 5 seconds before altering course. Begginers were found to be able to lookout when maneuvering, but they cannot found the danger.
These results suggest that boat’s operator keep lookout with understanding of dangerous objects to accidents at sea and contribute to safety navigation.
Authors have studied “the tsunami hazard database for vessels” to evaluate tsunami damage in Japanese major ports according to certain standards. The MPS method, a type of numerical simulation method was used in order to configure this database in the previous report; however, the simulated tsunami was the steep solitary wave, and the simple linear spring model was used for mooring lines. In this paper, we developed two improved models, “the tsunami making boundary” that generates a simulated tsunami with a long wavelength and “the nonlinear mooring model” that characterizes nonlinearity of mooring lines well. Moreover, breaking criteria for mooring lines in the tsunami hazard database was updated by using the three-dimensional MPS method applying these improved models and it was revealed that these models developed in this study have the usefulness by the comparison with previous models.