Analysis of the Influence of Rolling Motion on the ROPAX Vessel with Firewater Accumulation

Abstract

After firewater accumulates on the vehicle deck of a roll-on/roll-off cargo and passenger (ROPAX) vessel, the rolling of the vessel in a seaway can lead to the unexpected and rapid worsening of the situation. This paper provides insight into the impact of the rolling motion on a ROPAX vessel that is inclined due to firewater accumulation. Firstly, the stability of the vessel after firewater accumulation is computed using characteristics of the heeling moment developed by accumulated firewater in order to check the residual stability resisting wind and waves. Secondly, to analyze the rolling motions of a ROPAX vessel with firewater on one side, a new rolling equation was established after the introduction of the moment of accumulated firewater to the traditional rolling equation. Furthermore, the influence of cargo shift on the rolling motion also is introduced and computed. Finally, the approach was validated by analyzing a historical incident of a ROPAX vessel involving both firewater accumulation and cargo shift. The computational results derived show that the rolling of a ROPAX vessel after firewater accumulation and cargo shift will cause a loss of stability at the listing angle which is earlier than that obtained from the traditional method. Thus, the quasi-static listing angle due to firewater accumulation and cargo shift should be controlled within a safe range in order to prevent the vessel from being flooded during the rolling motion, and firefighting actions using water should be ceased temporarily to decrease the likelihood of the vessel capsizing and being lost.