The operational limitations are discussed at the IMO as a part of the second generation intact stability criteria. Since it is a first attempt to introduce operational efforts into safety regulations, comprehensive discussions are necessary to realize practically acceptable ones. Therefore this study investigates actual navigation routes of container ships and pure car carriers in the trans-North Pacific Ocean in winter, because they are prone to suffer significant parametric roll which is one of stability failure modes. Firstly, interviews are made to shipmasters who have experiences to have operated the subject ships to identify major elements for route selection in the North Pacific Ocean. Secondly, sufficient number of actual navigation records is collected from Satellite AIS data to derive the weather criteria for the route selection in severe weather condition. Finally, shipmaster's on-board decision-making criteria are discussed by analysing the ship tracking data and weather data.

As fundamental research of the operation of autonomous ships on the monitoring screen on shore, this paper focused on the differences in collision avoidance judgments based on various information sources, specifically via radar and via visual confirmation. Experiments were carried out using a ship-handling simulator with 14 seafarer trainees who had acquired the same level of maritime knowledge but had no actual experience at sea. Two experiments were carried out: a simple situation with one target ship appearing, and a complex situation where several targets appeared. The judgments in the complex situation showed that radar decision timing was quicker than visual decision timing. On the other hand, the simple situation showed no difference in course alteration and timing. Further results indicated that evaluation of the involved ships in the situation and the back ground of judgments varied depending on information sources. It is suggested that evaluation of the involved ships and the back ground of judgments may lead to differences in collision avoidance judgments. 本研究では，画面上に表示された情報による遠隔操船を考えるための基礎的研究として，操船シミュレー タを用い，目視情報のみを使用し衝突回避判断を行う実験と，計器情報(レーダー)のみを使用し衝突回避 判断を行う実験を，出現する隻数の異なる2種類の交通流で実施し，情報源の違いによる衝突回避判断に関 して検討を行った．実験参加者は，知識はあるが実航海での経験がない14名であった．衝突回避判断および 衝突回避判断に関わる事項を調査分析した．その結果，他船が一隻の状況では衝突回避判断に差がないが， 他船が複数隻存在する状況では，計器情報の方が早めに衝突回避を行うことが示された．このことは，衝突 回避判断に関わる事項( 「関心を抱く船」 ， 「衝突回避判断の背景」 )において，情報源間で差異が生じている ためと考えられた． (キーワード：情報源，衝突回避，レーダー，判断，遠隔操船)1 受付：2016年7月18日 受理：2017年10月24日

The AIS (Universal Ship-borne AutomaticIdentification System) is required to install in international ships with 300GT or above and domestic ships with 500GT or above. Nowadays, many ships are transmitting the AIS information. The received AIS information from other ships, is displayed on navigation equipment such as ECDIS (Electronic Chart Display and Information System). This information is used for safe navigation. The AIS transponder can be installed any ships other than AIS mandatory ships. Simplified AIS called as class B AIS, which is designed for small scale vessels is inexpensive than normal class A AIS. Class B AIS became more popular, becauseit can be equipped into small craft such as pleasure boat, yacht, motorboat, etc., and small size domestic vessels.In this paper, the design of the navigation system in a small boat equipped with Class B AIS is described. We propose the display method of AIS information on the navigation screen, considering the differences in data specification of Class A and Class B AIS. We hope that the navigation system for small vessels will become popular and contribute to the safe voyage of small crafts equipped with class B AIS.

The purpose of this study was to examine whether the collision avoidance judgement of seafarers is affected by each information sources, radar and visual. 22 seafarers who had onboard experience participated in the experiments using ship-handling simulator. Subjects were divided two groups, one group was conducted experiment for visual source, and another group was for radar source. This study investigated influence of each information source basis on results of their judgement, reasons why they made the decision, vessels which they paid attention to during experiments, and evaluations of their decision making by themselves. As a result, the judgements in both sources showed no differences. It was suggested that ships which the subjects paid attention to the decision making was different between each information source, even if the results of their decision were the same.

No abstract