The size of new passenger ships is continuously increasing. Bigger size offers bigger opportunities and economics of scale. However, when ships accommodate more passengers there may be a higher risk if evacuation is needed. Thus, new approaches have to be used and further developed in order to have the flooding under control if the watertight integrity of the ship is lost.
In the worst case, flooding accidents may lead to capsizing or sinking of the ship. The need to ensure safe return to port or at least sufficient time for abandonment will form a major challenge in ship design.
However, the assessment of the available time and the evacuation decisions are not easy tasks. This process is complicated and there is a notable lack of data. Thus, guidelines and methods to tackle these problems must be developed. New tools are required in order to increase the designers' and operators' possibilities to reliably evaluate the ship's capability to survive in flooding accidents.
The FLOODSTAND objective is to:
- increase the reliability of flooding simulation tools in design and onboard use by establishing modelling principles and uncertainty bounds, and
- to establish a method for instantaneous classification of the severity of ship flooding casualty.
Unlike any current regulations, the envisaged standard will reflect the stochastic nature of the damaged ship stability in waves. It will be based on first-principles modelling and thus it will reflect the nature of foundering as a process comprising loss of either (or both), flotation and stability, but also and more importantly, ultimate loss of human life. As it is risk-based, the standard will form a basis for decision support.
It is expected that by explicit disclosure of the risks associated with ship flooding and thus addressed from early design to operation, the safety level can be raised substantially from levels of current legislation.
Full scale tests of doors have been helpful in understanding the flooding process. The project provided valuable information to improve the SOLAS2009 calculations. Vulnerability calculations have proven to be very helpful to alerting the crew during operation. Furthermore, the project provided more reliable input data for time domain calculations.
Only a small number of semi watertight doors have been tested. Note that the lack of testing results with respect to fire and joiner doors, has led to assumed values of leakage and collapse pressure.
The project offers the followings suggestions:
- Project results need to be implemented into some of the SOLAS regulations;
- Designers and operators need to consider watertight integrity and operational needs at an early design stage;
- Design ships that allow to keep water tight doors (WTD) closed at all times.
Only a limited number of semi watertight doors have been tested. Due to the lack of testing results, all leakage and collapse pressure values are needed to be considered as assumptions.
To provide detailed input into the process of time-domain flooding simulation, there is a need for systematic tests of various door types. More tests are needed to establish the leakage and collapse pressure thresholds.