The existence of small crafts hardly stands out at night since the height of their navigation lights is lower and their luminance is weaker than those of large vessels. That affects ship collision accidents concerning with small crafts. In this paper, making their existence stand out by exhibiting LED tape lights (also called LED strip lights or LED ribbon lights) has been proposed. Through some experiments, it has been verified that small crafts exhibiting the LED tape lights have the following advantages. (1) Their existence is easily recognized by other vessels. (2) The course of them cruising at night is correctly judged by other vessels. It has been also confirmed that the LED tape lights cannot be mistaken for the navigation lights specified in the rules and do not impair their visibility and distinctive character, and interfere with the keeping of a proper look-out. In addition, LED tape lights in blue color have been proposed to exhibit because of the contrast to the navigation lights and to the background of city lights.
Collisions between fishing vessels and other vessels lead to many dead or missing fishermen, and the impact on society is very large. According to Article 18 of the “Act on Preventing Collisions at Sea” (hereafter referred to as Prevention Law), vessels engaged in fishing are granted priority of navigation. As a prerequisite for this priority status, it is necessary to display lights and shapes specified by Article 26 of the Prevention Law. Vessels engaged in fishing often do not show up on radar, so it is very important for ship operators to display the required lights and shapes as a means for visual judgement of nearby vessels. Collisions of vessels engaged in fishing can occur when they do not display lights and shapes while at sea.
Compounding this problem, it can be difficult for ship operators to determine whether to apply Article 18 of the Prevention Law, the fixed navigation law, or Articles 38 and 39 of the Prevention Law(1).This study examines the circumstances of vessels engaged in fishing that do not display legal lights and shapes, and also investigates the problem of the prerequisites for vessels engaged in fishing. Finally, differences of applicable navigation regarding these rules and regulations are also taken into consideration.
This study was made to determine index and standard model for education and assessment of Ship Handling Simulator. In this study, first the experiment using the BRM training scenario are carried out for professional ship’s officer and student. During the experiment, their communication are recorded by video camera and voice recorder. Next, the difference of communication between the navigator and student is analyzed by the data. From the result, the time of communication and time per minute of the navigator became more than them of the student. And Resource sharing and Cooperation action were defined as the index to assess communication and Evaluated Standards of Resource sharing, Positioning and Cooperation action were proposed as standard to evaluate communication. The concrete examples of assessment for communication were given. Finally, the way of effective education using the model of communication and the play back of operation by the navigator were proposed.
Many studies on ship mooring problem in ports and harbors during swell and long-period waves have been carried out from 1950s, and a guideline for the problem has been issued as a manual in Japan. However the ship mooring accidents and interruptions of cargo handling due to the large ship motions have been occurred and remained at terminals located at an exposed area to the ocean. In order to find out a solution of the problem, a numerical simulation system for moored ship motions in time domain is generally used and available nowadays. In this study, we have investigated on effect of hydrodynamic forces such as added-masses, damping coefficients and exciting forces for the system by comparing the calculated results with experimental ones derived from physical model tests on moored ship motions. Two analytical methods on hydrodynamic forces: 3-Dimensional domain division method of which ship shape is modeled as a rectangular and 3-Dimensional Green function method of which ship shape is treated as the actual body, are used in the investigation.
Recently, Unmanned Aerial Vehicles (UAV), represented by Multi-copters are often used for observation of farm land, forest and volcano, surveying and so on. However, it will take much time for multi-copters to complete the observation of the large farm land. This also requires the change of battery of multi-copters, leads to the increase of cost and make it impossible to get the image of the land under the uniform sun-light conditions. In order to shorten the time, the observation system by fixed wing UAV driven by fuel engine is proposed because the UAV can usually fly faster and longer than multi-copters. This paper describes the design of the UAV, which meets the take-off, climb, cruise and landing performance, and the flight verification of the take-off and onboard equipment weight.
Recently, Vessel traffic service (VTS) operators are highly required to get the ability to manage traffic flow, by detecting Conditions that Requires Attention (CRA) from the monitoring screen. The authors elucidated the cognitive processes of VTS operators for detecting CRA, after that they are planning to propose training methods for the inexperienced operators. As the first step of the study, in order to acquire the cognitive contents of VTS operators, we observed the difference of management process between inexperienced and experienced operators by the experimental analysis based on an on-site viewpoint. A series of traffic management process experiments by using a simulator for training VTS operators was carried out for both inexperienced and experienced operators. In order to understand the management process of operators, we proposed a management task chart based on the results of the experiments. The result shows that the inexperienced operator handles a few CRA intensively, while the experienced operators handle many CRA at the same time. It also shows that in order to make more rational the management task, it is necessary to properly select the concerned ship of CRA, the contents and the timing for calling the ship.
The large swells invade the Toyama Wan from October to April every year,and cause wave disasters such as ship dragging anchor, grounding and so on, around the Toyama Wan. It is considered that the wave disasters are mainly caused by swells and water level fluctuations with long periods, and so beat phenomena of swells and periodic water level fluctuations are investigated using water level data observed from December, 2017 to March, 2018. The following results are obtained.
(1)There were proper oscillations with periods of about 1.5 minutes, 13 minutes, 30 minutes and so on, in the coastal water of Toyama Wan.
(2)It is confirmed that swells beat with period of about 30 minutes due to the periodic water level fluctuation with period of about 30 minutes.
These results suggest that swells beat with more long period such as a period of about 12 hours, due to ocean tide. It is a future problem to investigate a possibility that swells beat with more long period such as a period of about 12 hours, due to ocean tide.
Ferryboat's passengers often see other ships, but in many cases, they do not know what type of ship those are. In recent years, the holding rate of portable information terminals such as smart phones and tablets got higher. Also, an environment that makes it easy to acquire ship information has been prepared with the spread of AIS.
In this research, authors applied a virtual reality technology and information technology to the maritime technology fields and developed a system which displays some information of the ships and sightseeing spots displayed in the camera image.
National Maritime Research Institute (NMRI) conducted an accident analysis involved in two container ships at Hanshin Port in 2016 at a part of investigation by Japan Transport Safety Board (JTSB). A purpose of the analysis was to investigate backgrounds of the accident systematically with a different way from the traditional survey.
The investigation was mainly conducted from two view points, i.e.
1) assessment of situation awareness based on evaluations of the collision likelihood level using AIS data and
2) CREAM (Cognitive Reliability and Error Analysis Method) analysis which is a method of Human Reliability Analysis.
This paper describes the result from the former view point. In order to evaluate situation awareness at the incident, the authors analysed time variations of the ships' state quantity and collision likelihood between collided two ships. Collision likelihood was estimated by indices as CJ (Collision Judgement), SJ (Subjective Judgment), CR (Collision Risk), BC (Blocking Coefficient) and OZT (Obstacle Zone by Target). From the results, it deems that operators of the ships could aware the likelihood of collision at some timing before the collision. Besides, it indicates that estimated value by CPA (Closest Point of Approach) analysis might cause delay in awareness of the collision likelihood of operators because the larger ship length is, the larger difference between CPA analysis and actual value becomes.
Unmanned surface vehicle (USV) is one of the effective devices for environmental monitoring of ocean. To monitor the wide area of ocean simultaneously, we need to distribute a group of USVs that can cruise autonomously. Development of control algorithm for these USV group is important and a tank experimental system is necessary for a design spiral of control algorithm investigation.
In this research, we developed a set of tank experimental system aimed for study on control algorithm of USVs. The system consists of two catamarans that equips a forward camera, AR marker, wireless communication module and a single board computer to integrate all modules, which are intended to emulate AIS, GNSS and Radar in the real system. Two cases of collision avoidance algorithm are tested using this system. The first experiment is each ship has the same program to change its heading to avoid the possible collision. The second experiment is one ship slows down and the other ship changes its heading. Through these experiments, we confirmed our experimental system worked well and effective for the investigation of control algorithm development of a USV group.
Existing methods of obtaining MSI (Maritime Safety Information) take traditional style. Purpose of this study is to solve disadvantages of NAVTEX and EGC receiver. Our developing systems can help every deck officer by automatic processing of MSI. These systems are able to extract characteristics from MSI. It is important to understand for specifying locations where and when exercises are conducted or terms of them. All deck officers don’t need correcting past data of MSI printed by NAVTEX receiver, because it will do the works instead of deck officers and can also work continuously and more precisely. It also can select any helpful information from MSI on web site by deck officers and can search related information to build a navigational plan. Learning from these results, any deck officers who aren’t good at English can understand MSI easily.
Accident investigation is conducted because understanding the cause of it is important to prevent marine traffic accidents. When the causes are related to human factors, especially to cognition and decision making of human beings, it is difficult to organize the causes and explain the facts.
In this paper, actual collision accident is analyzed using CREAM (Cognitive Reliability and Error Analysis Method), to organize, to analyze the cause and consequence relations, and to explain the cognition and behavior extracted from the communication record and testimonies. As a result of analysis, communication barrier among the parties concerned was identified as the maximum influent to the inappropriate behaviors.
A variety of applications have been made for the safety and efficiency of ship operation, using AIS (Automatic Identification System) information which can grasp a wide range of ship movement. The purpose of our study is to predict the ship’s route using AIS information keeping in mind practical applications such as preventing aground and predicting traffic congestion in the concerned sea area.
We framed the mesh data based on the record of traffic flow in the target area of the sea, which was gathered from AIS information, and hypothesized a network (graph) onto the target area based on the connectivity (ease or difficulty of connection) to the 8-neighbours cells around the interested cell, which was determined by the high or low of the navigation record counts and the distribution of the ships traffic flow directions. In this way, we constructed a process to predict the ship's path based on the shortest path method (Dijkstra's algorithm).
The waters facing Toyama-Shinko Port (Fushiki Toyama Port Shinminato District) in Toyama Bay combine inflows from the Shinbori, Uchi, and Gejou Rivers with those of the open sea. Some unique flows occur in the harbor due to density differences between these two water masses, tidal forces, and the influence of the sea bottom shape. Regarding the coast around Toyama Bay, we have regularly investigated the structure of the water masses since 2003 and found that they are influenced by river water, the Tsushima warm current, and the characteristics of seasonal fluctuations.
In the present study, we conducted an ocean environmental survey using a Conductivity, Temperature, and Depth (CTD) profiler at various points inside the harbor at different locations ranging from the harbor entrance to the rivers in the harbor. In addition, we compared the results of surveys of the open sea and inside the harbor. In the CTD observations conducted in June and Sep. 2017 and Feb. 2018, we found that the influence of river water was strong from the surface to a depth of approximately 2 to 3m, and that dense seawater, similar to that of the open sea, was widely distributed in the deep water below the surface layer. And, we performed Acoustic Doppler Current Profiler (ADCP) observations in the harbor. The results indicated that the flow direction differed between the river water layer and the outer sea water layer.
When tsunamis attack the harbors, the first attack of tsunamis has two forms; leading waves and backwash. And, it is difficult to predict the form of the first attack of tsunamis. Also, because leading waves and backwash are alternated in tsunami, it is necessary that damage protection measures of mooring vessels against both leading waves and backwash are considered. Authors have been mainly studying about damage protection measures of mooring vessels against the leading waves. However, backwash have hardly been studied. In this study, the influence of backwash against mooring vessels at a wharf was examined. The three dimensional MPS (Moving Particle Semi-implicit) method was used. Backwash was expressed as the dam break phenomenon. Outflow angle, flow velocities and mooring conditions were considered. As a result, a safety of the mooring against backwash was evaluated.
Crew member fatigue has been reported as one of the causes of marine accidents. In our previous study, it was found that human energy expenditure increased in a small marine craft because of the standing postural motions, such as motions of the head and the hip. The purpose of this study is to analyze the relationship between standing postural motions and energy expenditure, assuming that these motions are one of the causes of physical fatigue. Three orientation sensors capable of measuring linear accelerations and angular velocities were placed on the head and hip of each participant, and on the floor of the marine craft, to analyze the postural motions. Energy expenditure was measured using a calorimeter. The relationship between the standing postural motions and their energy expenditures was analyzed by multiple regression analysis of the following variables: energy expenditure, height, weight, and root mean square values of surge, sway, heave, roll, pitch and yaw motions at the head and hip of each participant, and on the floor of the marine craft. It was determined that weight and the pitch motions at the hip were especially affecting energy expenditure. The coefficient of determination was 0.71. Thus, it was suggested that the pitch motions at the hip affect the energy expenditure in the small marine craft.