Going back from risk duos to risk triplets: The case of maritime accidents in adverse weather conditions

The establishment of new regulatory requirements from the International Maritime Organization to effectively control and limit toxic gas emissions from ships, has sparked the debate of whether ships, when complying with these... [ view full abstract ]

The establishment of new regulatory requirements from the International Maritime Organization to effectively control and limit toxic gas emissions from ships, has sparked the debate of whether ships, when complying with these requirements by simply derating the main propulsion engine, are adequately equipped to safely operate in various weather conditions. This study deals with assessing and analyzing the risk of navigational accidents, i.e. collisions, groundings and contacts, that occurred under adverse weather conditions and may have been related to the lack of sufficient powering and maneuverability. The risk assessment methodology that has been developed for this study is based on the concept of risk triplets that are used to connect an adverse scenario to the frequency and the resulting consequences. The adverse scenarios are defined using a set of parameters, including ship type, size class, accident type and installed main engine power. The implementation of risk triplets allows a more detailed assessment of the accident risk, which in turn supports the identification of specific size classes, within ship types that are involved in specific accident types, that are most at risk. Additionally, risk triplets incorporate enough information for producing various graphical risk curves that are used to compare the different adverse scenarios and focus on the ones with the highest risk. A risk based approach is important when examining ship accidents due to the multitude of possible consequences to the ship itself, such as Loss of Watertight Integrity (LOWI), to the human element as well as the marine environment, in conjunction with the variety of parameters that define a specific accident scenario. The study concludes with interesting results regarding high risk ship types and insights that can be used to strengthen the case for science-based policy making in the maritime industry.