This course examines the causes and controversies surrounding the Sewol ferry disaster, explains the key concepts of ship stability – heave and resilience – and suggests technical and policy responses to ensure safe ship operations.
The Sewol ferry disaster happened a long time ago and left many Koreans grieving. It was not just a disaster, but a tragedy that left deep scars on Korean society. Since the accident, the truth has been slow to emerge, and theories about the cause of the accident have been poured out through various media. This situation further confused many Koreans, which further broke the hearts of many people. The main causes were pointed to the lack of safety management on board the ship and the lack of response from relevant organizations. However, the problem cannot be seen as a failure of management alone. The root cause of the accident lies in our understanding of ship stability.
Ship stability is not just about physical factors. Safe navigation requires a complex set of considerations in the design and operation of a ship. The main factors that affect a ship’s stability are heave and resilience. Heave is the force that causes a ship to tilt, and restoring force is the force that brings a tilted ship back to its original state. When the balance between tilt force and restoring force is disrupted, the boat is at risk of capsizing.
Now, let’s take a deeper look at the factors that generate tilting forces. The first is the pressure exerted from the outside by strong waves and wind. In a typhoon, the strong waves and winds create a tilting force on the ship, which puts it in a dangerous situation. The second is the tilting force caused by the movement of cargo or fluid inside the ship. One of the main causes of the Sewol ferry accident was the unstable securing of cargo. If the cargo is not secured inside the ship and it moves rapidly, it can create a tilting force that causes the ship to tip. Thirdly, the resistance of the water when the ship is turning can cause heeling forces. Finally, there is heeling due to hull damage. For example, if a ship hits a reef or glacier and breaks its hull and sinks.
When a ship is tilted in this way, restoring forces come into play. This force plays an important role in maintaining the stability of a ship, and it’s created by the interaction of gravity and buoyancy. The center of gravity of the entire ship is called the center of gravity, and the center of buoyancy is called the center of buoyancy. When a ship is tilted, more of the tilted side is submerged in water, which shifts the center of gravity toward that side. This gives the boat more buoyancy on the tilted side and forces it to return to its original position. However, if there is not enough resilience, the tilting force will exceed the resilience and the ship will capsize.
To design and operate a safe ship, it is important to maximize resilience. To achieve this, it is essential to ensure that the center of gravity and the position of the buoyancy center are properly adjusted to ensure stable resilience. These factors should be taken into account from the design phase of the ship, and care should also be taken when loading cargo. In particular, the location and arrangement of cargo can have a significant impact on the ship’s resilience.
In addition, to increase the safety of the ship, it is essential to install devices that reduce the sway. The first is the bilge keel, which is installed under the left and right sides of the ship to repel water when the ship is rocking, thereby suppressing the sway. There are reports that this device was not functioning properly during the Sewol ferry accident, which is a reminder of the importance of having a device that prevents the ship from swaying. The second is the antiroll tank, which is a tank installed inside the ship, and when the ship rocks, the liquid inside the tank acts to offset the ship’s motion.
These technologies are essential to making ships safer, and understanding their stability can help prevent accidents and enable better responses when they do occur. The Sewol ferry accident reminded us of the importance of ship safety, which is not just a technical issue. Therefore, understanding these fundamental concepts and technologies is crucial to avoid repeating tragedies like the Sewol. It is also hoped that this understanding will help readers to better understand the Sewol debate and make informed decisions about future ship safety issues.
Along with this, it is also necessary to criticize the way the government and related organizations responded after the accident. The Sewol ferry accident could have been prevented if safety regulations had been strictly implemented and monitored. Safety cannot be overemphasized. Along with technical understanding, it requires thorough preparation at the social and policy level. This requires public attention and continuous monitoring, which will eventually lead to a safe society.
