Improvement of Polar Operational Limit Assessment Risk Indexing System Based on a Probabilistic Method

Ships sailing in polar regions are faced with situations of collision with ice, resulting in the risk of structural damage. To assess the risk level, International Maritime Organization (IMO) recommends using the Polar Operational Limit Assessment Risk Indexing System (POLARIS). The system uses Risk Index Outcome (RIO) values to classify risks and provides corresponding operational recommendations. However, the interaction between ship and ice is a random process, and POLARIS does not explicitly take into account the highly stochastic nature of ice loading. This paper presents a possible improvement to the POLARIS through the incorporation of a probabilistic approach known as the extended Event Maximum. A detailed case study with the S.A. Agulhas II exemplifies the integration and application of this method. Return periods are used to replace RIO values to provide a probabilistic perspective into POLARIS. Comparisons are made between RIO values and return periods. The results indicate that the integration of the extended Event Maximum Method is more rational and able to take into account the probability factors compared to the conventional RIO values, thereby enhancing the ability of POLARIS to inform operational decisions and risk management strategies in polar marine operations.