Multi-stakeholder decision-making in the risk-based design of a RO-PAX double bottom for grounding

Abstract

Grounding accidents can be fatal for ships. This paper discusses decision-making in risk-based design to avoid such outcomes for a 30 000 GT RO-PAX in a powered hard grounding. Five alternatives of a double-bottom structure are suggested to reduce the risks of loss of life, environmental damage, and material damage. Risk assessment concentrates on the consequences, applying numerical grounding simulations to model the energy absorption of the proposed alternatives. To determine the risks, 1295 Monte Carlo simulations are performed running a quasi-static model of ship motions. Accounting for these risks and the added production costs and operational loss, a new multi-stakeholder approach for selecting alternatives is proposed assuring simultaneous maximal satisfaction to both the shipyard and the ship owner. As an outcome, two alternatives are selected, the first increasing the bottom shell thickness by 50 per cent, and the second increasing the stiffness of longitudinal stiffeners by 90 per cent. If observing their performance, it is possible to recommend the latter as the most effective solution. Such an outcome is in accordance with the established practical opinions in increasing safety for grounding, proving sagacity of the presented approach.