Operational risk assessment model for marine vessels

This paper presents a practical approach to quantify the risk associated with different systems in a marine vessel using the existing operational database. A structured bow-tie methodology is proposed to assess risk. The first step was the development of probable failure scenarios for four different events, namely, fire and explosion, propulsion engine failure, power failure, and maneuverability failure. The second step includes the formulation of corresponding bow-tie models representing these scenarios using vessel configuration and process information. Using the failure data for different elements obtained from the vessel's maintenance logbook and incident records, the frequency of events and failure rates of the safety barriers are estimated to quantify risk. Operational data from the vessel, a single engine ice-breaker bulk career navigating mainly in the Canadian sub-arctic region, validated the proposed model. The methodology is verified by comparing the model's observations with an alternative dataset (actual failure scenario from the ship). The proposed methodology is expected to serve as a useful tool for marine vessel's safety and risk management.