Vulnerability assessment of surf-riding-broaching and pure loss of stability for Systematic Series D1 model

This paper is focused on the first and second level vulnerability assessment of Surf riding/Broaching and Pure Loss of Stability Criteria according to IMO second generation intact stability criteria. The calculations are performed for the semi-displacement twin-screw round-bilge hull form model D1 of the Systematic Series D. This model has hull form and service speed representative of corvettes built in 90-ties. The considered loading condition is obtained from Italian Navy ships statistics. Both criteria are analysed for different operational characteristics to evaluate the speed limits where the ship is not vulnerable. Model D1 is found to be vulnerable to both failure modes at service speed. Performing 2nd level of both criteria 'safe' speed is around 19 knots for surf-riding and around 15, 5 knots for pure loss. The obtained results are commented and compared against similar ships from the relevant state of the art papers.