Analysis of Firewater Accumulation and the Securing of Vehicles on ROPAX Vessels

During the process of firefighting on the vehicle deck of a roll on/roll off cargo and passenger (ROPAX) vessel, firewater accumulation and cargo shift can lead to the unexpected and rapid worsening of the situation. This paper provides insight into the impact of firewater accumulation and assesses the risk of a resulting cargo shift. A novel approach is proposed for ensuring that vessel stability remains within safe margins of operation once firewater accumulation has occurred. First, the critical listing angle at which vehicles on deck have a high risk of shifting is identified for a particular vessel. Second, a new iterative method is designed to calculate the weight and moment of the accumulated firewater causing the vessel to reach its critical angle. Third, the vessel's stability under the combined influence of firewater accumulation and total cargo shift is calculated. Finally, the method is validated through consideration of historical firewater accumulation and cargo shift incidents on ROPAX vessels. The computational results derived show that, during firefighting operations, action should be temporarily ceased if the vessel lists to its critical angle. Failing to do so leads to the increased likelihood of the vessel capsizing and becoming a total loss.