The capsizing and sinking of Sewol lead to the death of 304 people, mainly secondary-school students. Earlier investigations have not answered all questions. As part of their investigation, the Sewol Investigation Commission therefore ordered MARIN to conduct extensive computer simulations, model tests and a simulator investigation into the manoeuvring, capzising, flooding and sinking of the vessel.

Extensive tests with a 1:25 model of the vessel were conducted for more than 200 scenarios in MARIN’s Seakeeping and Manoeuvring Basin. These cases consisted in a variation of important parameters, such as stability, propulsion, steering and fin stabilisation. The effects of moving cargo and possible external forces were included during the model tests. The human factor in possible steering actions was investigated in MARIN’s Full Mission Bridge nautical simulator by means of real-time simulations.

For the flooding tests a 1:30 carbon model was manufactured and equipped. All relevant water tight compartments were modelled and all 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 utilizing an 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 MARIN’s Depressurized 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.

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.