SEWOL Ferry Capsizing and flooding Henk van den BOOM, Victor FERRARI, Rinnert van BASTEN BATENBURG

Seung Taek SEO [SIC] HIMT/RINA Sustainable and Safe Passenger Ships, Athens 2020

16 APRIL 2014; 08:48 - 09:40

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16 April 2014; 476 people on board

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172 people saved

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Sewol

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Approach

• Phase I: Turning & Heeling (< 45 deg)

Manoevring tests & Simulations • Computer simulations

• Model tests 1:25

• Navigation Simulator

• Phase II: Flooding & Sinking (> 45 degrees) • Model tests 1:30

• Computer simulations

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Data made available

• Vessel geometrie

• Cargo mass & positions

• Tank volumes ?

• Centre of Gravity ??

• AIS position

• AIS heading (??)

• Heeling angle from dash cams in trucks

Transverse Stability

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• Ship geometry • Center of Gravity • Light weight ship

• Tanks (fuel, water, ballast)

• Free surfaces

• Cargo (cars, trucks & other)

• Passengers

Stability SEWOL

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• Arm of Stability GZ

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0 20 40 60 80

Stab

ility

arm

[m

]

Heel angle [degrees]

GZ

GM

Phase I Turning & Heeling Tests

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Active systems:

1. Propulsion

2. Rudder autopilot

3. Stabilizing fins

4. Moving cargo

5. External Force

• Schaal 1:25 model

Moving Cargo modelling

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• Cargo lumped into 4 masses

• Transverse rail; linear motors

• Computer driven

• Settings: trigger angle, sliding acceleration, speed, excursion

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Turning test GM2C, speed 17.5 knots, rudder 25 degr. SB

Test program

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• Stability levels GM=0.01-0.65m • Rudder scenarios • Propeller scenarios • Sliding Cargo scenarios • Ship speed • Initial heel • Trim • External force (Winch)

Free sailing tests

Navigation Simulator

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• 360 degrees outside view

• Manoevring Model

• Schip motions emulated in outside view

• Investigation “human factors”

• Steering scenarios

• Stability levels;GM=0.01-0.6m

Effect of stability & steering (model test results)

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• Effect of GM on heel • Effect of Rudder on heel

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Longitudinal location of mass / bow trim (model tests)

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Model test results compared with AIS track

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Phase II Flooding & Sinking

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Location Vent E-deck

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Captive Flooding tests

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Free Flooding tests

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Flooding tests & simulation compared with actual video

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Salvage March 2017

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Lifting (March 2018)

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Inspection May 2018

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External Force?

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Main Conclusions

• Stability of SEWOL was lacking (conversion, cargo, tanks, trim)

• Rudder excursion occured (helmsman, steering gear)

• Fast Turn with Large Heel (>18 degr.)

• Cargo (not properly secured), slided at 18 and 33 degr. heel

• The heeling increased to 45 degr.

• Water ingressed via scuppers and vent at C-deck

• Water flowed through vent pipe into stabilisation room and E.R.

• Due to water on C-deck, ferry capsized and flooded fast.

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