Air bags could keep sinking ships afloat
The European Union has invested in a project designed to keep damaged ships stable and afloat by means of airbag-like balloons. It is hoped that the new system, developed under the Su Sy project, will give emergency services extra time to evacuate stricken ships, minimizing the devastating losses of life synonymous with the sinking of cruise ships such as the Costa Concordia, and the South Korean ferry Sewol, which sank earlier this year.
The hulls of modern ships are almost always constructed with multiple compartments designed to limit the effect of a hull breach, containing the seawater and effectively keeping the ship seaworthy. The problem comes when multiple compartments are breached consecutively, as is often the case when a ship runs aground. Such a breach would allow massive amounts of seawater to gush in, causing the ship to list to one side. This listing often results in the ship capsizing completely, making further rescue attempts perilous for both survivor and diver alike.
The Su Sy project aims to counter this deadly effect with the use of inflatable balloons placed either in between the double hull of a vessel, or within its ballast water tanks. The technology used to rapidly inflate the balloons is a re-purposed form of a submarine rescue system utilizing cartridges containing potassium nitrate, an epoxy resin and ferric oxide.
When activated, these components inflate the balloon at high speed with the ferric oxide (also known as rust) acting as an explosive catalyst, dramatically speeding up the process. There is a problem with the inflation process, however, wherein a significant amount of heat is created, with the potential to damage the skin of the balloon, or even ignite flammable cargo.
Engineers plan to counter the thermal issue by injecting cool air into the chemical explosion either via a second canister, or by means of a heat exchange device. Once inflated, the Kevlar-reinforced balloons will push the water out of the hull, limiting further flooding at the point of the breach.
In the case of the Costa Concordia, three of the ship's side compartments were breached, leaving the liner half submerged, making rescue attempts difficult. In such a situation, the Su Sy ballast balloons may have been able to limit the influence of the flooding, helping to keep the ship upright and afloat. This would have granted the emergency services more time and options regarding how to evacuate the passengers, limiting the loss of life that resulted from the tragic event.
However, there are concerns from prominent voices within the maritime community, that doubt the reliability of the balloon system. One such concern involves the extra cost that implementing these features in ship construction would require. Another regards the difficulty in maintaining the systems once they are installed.
The project's scientists are aware of the issues, and believe that making small changes, such as adding controls to the gas exhaust to control the level of outflow, will make it a viable option in the future.
Source: European Research Media Center