Surf-Riding-Broaching and Pure Loss of Stability vulnerability on Systematic Series D1 Model

The development of the IMO second generation intact stability criteria is based on a multi-level approach. In each level the accuracy of the analysis is increased and if a possible vulnerability is detected the next level is applied. A ship, depending on its characteristics and external conditions, may be considered vulnerable to one or more stability failure modes. For each of the stability failure modes, the study will begin applying the first level of vulnerability, and in case the ship is considered vulnerable, to one or more failure modes, the second level of vulnerability will be applied to specific mode. This paper is focused on the first and second level vulnerability assessment of the Surf riding/Broaching and Pure Loss of Stability. After testing the procedure on IMO benchmark ships, these two criteria are verified on the semidisplacement twin-screw round-bilge hull forms of the Systematic Series D, by Kracht and Jacobsen (1992), model D1. This model is representative hull form and service speed of Italian Navy ships and the considered loading condition is taken from the naval ship statistics. These two criteria are analysed for different operational characteristics to evaluate the speed limit