Vehicle securing safety assessments of a Korean coastal car ferry according to acceleration prediction approaches

Abstract

The capsize and subsequent sinking of a coastal car ferry occurred along the Korean coast, resulting in hundreds of casualties. The rapid course change of the ship might have forced improperly secured cargoes to rush to one side and accelerated the capsizing event. This paper provides a comparative study of vehicle securing safety assessments composed of evaluations of the external inertia forces and lashing strengths for a car and a truck. The external inertia forces were evaluated based on the IMO CSS (CSS approach) and rule-based maximum motion angles (RULE approach). Being a car ferry as a target ship, the sea states were collected along the most frequent seagoing routes of the target ship. Frequency domain seakeeping analyses (FSA approach) were carried out and then the long-term motion components were derived using the collected sea state data. The long-term motion components were put forward based on time domain seakeeping analyses (TSA approach). The TSA approach estimated the most optimistic external forces, while the CSS approach provided the most conservative external forces. Assuming the vehicles were secured symmetrically with four steel wires, the lashing strengths were derived. More numbers of lashing cables were required for the heavy vehicles when the CSS approach was applied, while other approaches predicted sufficient lashing strengths compared to exerted forces.