Reducing the risk of collision between ships in a close-quarters situation by simulating collision avoidance actions

Abstract

‘Close-quarters situation’ is a term used in the International Regulations for Preventing Collisions at Sea. As the term is not precisely defined, this paper analyses the interpretations and definitions of the term by various authors or courts, based on judicial processes and judgments. In the end, the authors suggest their own definition of the term ‘close-quarters situation’. Knowing the minimum distance from another ship and the time to the closest point of approach at which collision may still be avoided by one's own manoeuvre is information that every ship's officer needs to know. In accordance with the proposed definition of the term ‘close-quarters situation’, minimum distances between ships and time to the closest point of approach in which the ship can still take action to avoid a collision by its own manoeuvring are determined by means of simulations on a navigational simulator. A total of 168 simulations were performed with three fine-form vessel sizes and three full-form vessel sizes. Due to the extensive amount of data, the paper presents the results for one vessel only.

Analysis of the latest rudder application point in restricted waters

“…On the basis of previous studies, Li Wei [2] proposed that the latest rudder application point should be a dynamic model, analyzed the factors affecting the latest rudder application point, organized the factors into a tree hierarchy diagram, established the corresponding membership function for each factor affecting the latest rudder application point to express the magnitude of each phenomenon, and finally established the evaluation model of the latest rudder application point. D. Mahovic [3] used the navigation simulator to conduct ship operation experiments for many times, and determined the latest rudder application distance at the time point when the ship was operated at the last moment to avoid collision.…”

“…In formula (4), k = V0 / VT; α T is the relative angle of the relative speed of the target ship; DS is the minimum safe encounter distance, which can be obtained by formula (3). According to the above equations ( 3) and ( 4), the emergency situation distance is affected by the speed ratio of the two ships, the initial dcpa 0 , the relative angle of the target ship and the minimum safe encounter distance.…”

Safety First—A Critical Examination of the Lights and Shapes in COLREGs

“…Generally, when using radar observation from a long distance and considering radar errors, the minimum applicable distance for close-quarters situation is 3 nautical miles; In open seas with restricted visibility, for approaching vessels crossing the bow of the observer s vessel, this distance should not be less than 2 nautical miles. In congested waters, when the vessel is moving slowly or in an overtaking situation, this distance can also be less than 2 nautical miles [17,18].…”

‘A novel model blah blah blah’

“…Carral et al (2021) modelled both the operative and routine learning curves in manoeuvres in locks and in transit in the expanded Panama Canal, and for this they monitored the whole of the canal continuously for 42 months of operation, to make sure the seasonality and different context are all factored in. Djani Mohovic (2021) reduces the risk of collision between ships in a close-quarters situation by simulating collision-avoidance actions. Qi et al (2021) developed a cellular automaton-based model for ship traffic flow in busy waterways.…”