An Estimation Method for the Overthrowing Moment of Vehicles on the Car Deck of the Ro-Ro Ferry

Ensuring passenger safety and comfort is crucial for maintaining trust in sea transportation, especially as ship accidents remain a concern. One critical area for improvement is the vehicle fastening systems on Roll-On-/Roll-Off (Ro-Ro) ferries, which must account for fastening techniques and vehicle positioning to prevent shifting or overturning during adverse conditions. This study calculates the shear and overturning moments acting on vehicles when a ferry experiences rolling motion due to beam waves, using numerical simulations to evaluate the impact of vehicle placement. Wave heights were adjusted to reflect operational area conditions, and vertical and lateral accelerations were derived based on vehicle dimensions, type, and enter of gravity. A case study of a Ro-Ro ferry operating on the Bira-Pamatata route revealed that Bus 2, located at the rear centreline, exhibited the highest rolling moment of 14,370 N·m, while Ayla 21, positioned at the front centreline, had the lowest moment of 1,141 N m. These results demonstrate that vehicle mass, dimension, and vertical and horizontal center of gravity significantly influence rolling and share moments.