Sewol ferry capsizing and flooding

The capsizing and sinking of Sewol close to the South Korean coast in fair weather on April 16, 2014 caused the death of 304 people. In December 2017 the Sewol Investigation Commission of South Korea contracted MARIN to conduct an extensive investigation into the turning, capsizing, flooding and sinking of the vessel.

Systematic tests with a 1:25 model of the vessel were conducted for more than 340 turning and heeling scenarios in MARIN’s Seakeeping and Manoeuvring Basin. These cases consisted of variations in transverse stability, propulsion, steering and fin stabilisation. The effects of moving cargo and possible external forces were included during the free sailing model tests featuring five active control systems. The human factor in possible steering actions was investigated in a full mission wheelhouse simulator.

For the flooding tests a 1:30 carbon model was manufactured and equipped. The water tight compartments were modelled and relevant inflow openings, ventilation openings, ducts, hatches and doors were included in the scale model. Flooding tests were conducted in a controlled manner by using a captive model set-up utilising a hexapod actuator to force the vessel in the trajectory observed during the accident. The forces required to constrain the model were measured and showed the balance between the inflowing water and the instantaneous displacement of the vessel. The flooding tests were conducted in the Depressurised Wave Basin to reduce possible scale effects. With these captive tests the most likely scenario of flooding was determined. Finally, flooding and sinking tests were also performed with the model in free floating atmospheric condition.

The results of this investigation inspired additional research into the stability of passenger vessels leading to a submission to IMO MSC for improvement of the Intact Stability Code 2008.