Safety of an Indonesian ro-ro ferry with different weight distribution on vehicle deck

The intact stability of an Indonesian ro-ro ferry is assessed by using the Second Generation Intact Stability Criteria for dead ship condition with two different weight distributions. The first distribution corresponds to weights concentrated near the centreline of the model. The second one corresponds to weights located farther from the centreline, in order to obtain a natural roll period corresponding to that provided by the standard formula in the IMO level 1 criterion. Roll decay tests and roll tests in regular beam waves are conducted for those two different weight distribution to obtain the natural roll period, the damping factors due to breadth-to-draught ratio (X1) and bilge keels (k) as well as the effective wave slope coefficient, by using the three-step procedure test recommended by MSC.1/Circ.1200. The critical metacentric height in the level 1 criterion decreases as the roll radius of gyration increases. The weight distribution does not have a significant effect on the capsize index if the metacentric height is smaller than about 0.60 meters but it has a clear impact as the metacentric height increases. In the operation range of metacentric height, the capsize index is significantly affected by the weight distribution.