Assessment of a critical area for a give-way ship in a collision encounter

Abstract

Evasive action in ship-ship encounter has to be carried out on time and in line with the international convention on collision regulation – COLREG. The convention not only includes a set of rules defining types of relations between encountering ships but also indicates appropriate action to be taken in a given encounter. One of such encounters is crossing, where, in case of a collision situation, a give-way ship has to take an appropriate action in due time. However, a stand-on vessel is also given an opportunity to manoeuver, if it is made clear to her that the other ship is not fulfilling her obligations. However, it is difficult to specify, at which point in time in the course of an encounter, the stand-on ship has to take an action in order to avoid collision. It is understandable, as this parameter depends on numerous factors, both endogenous (e.g. ship characteristics, her maneuverability), and exogenous (e.g. type of encounter, weather conditions). Therefore in this paper we make an attempt towards the definition of the critical area for a maneuver of a stand-on ship, in the situation where the give-way vessel does not take an action. This is determined with the use of a hydrodynamic model of ship motion, and series of simulations conducted for several types of encountering ships under various conditions. Once determined, the critical area demarcates the no-go area around the own ship, where any other ships on collision courses must not enter. Otherwise a collision cannot be avoided by an action of one ship alone.

A Ship Domain-Based Method of Determining Action Distances for Evasive Manoeuvres in Stand-On Situations

“…Similarly to [25,26] the paper investigates situations, when the own ship is the stand-on ship. In such cases the situation is different from give-way: the manoeuvre of a target is expected and own manoeuvre is a last resort.…”

“…Unfortunately above research either featured only limited number of encounter scenarios or included simplified modelling of ship's dynamics. In [25] these limitations were finally overcome. Those authors assumed manoeuvres of the own ship alone and were interested in determining the last moment of the manoeuvre initiation assuring no collision.…”

“…A research presented in [25] and the works of their predecessors have inspired the research presented in this paper; however here it is focused primarily on ship domain utilization. We are interested in a time (and a distance, consequently) to a potential collision which still allows us to avoid the specified ship domain violation.…”

“…Therefore, the current paper uses both ship's domain and 2 Journal of Advanced Transportation ship's manoeuvrability models in order to determine the last moment when a particular collision avoidance manoeuvre still could be successfully performed. The method presented here was inspired by action area [24] and critical distance first described in [25] and further developed in [26]. This paper presents the method applied to solving the own ship standon scenarios resulting in displaying so-called action lines of distances, i.e., boundary lines defining ship's arena.…”

Merging Conventionally Navigating Ships and MASS - Merging VTS, FOC and SCC?

“…Algorithms and technical systems specifically addressing collision avoidance are well under way and proposals for solutions are under preparation for further discussion on international level (e.g. [15]- [18]). However, solutions need to take into account not only COLREGS but also objectives and operation of shore-based traffic management either of a private company like FOC and SCC respectively or a governmental institution like e.g.…”