Simplified operational guidance for second generation intact stability criteria

The SGISC have been developed to account for dangerous dynamic phenomena in waves. Five failure modes are defined, and a multi-layered structure, consisting of vulnerability criteria and Direct Stability Assessment, is adopted to check the ship vulnerability against each phenomenon. If the ship does not comply with one or more criteria, Operational Measures can be provided to reduce the likelihood of stability failures. The present paper provides an overview of Operational Measures and focuses on the application of the Simplified Operational Guidance (OG) for four different ships, each vulnerable to at least one of the failure modes. OG are derived according to IMO Interim Guidelines, by limiting ships’ operation in terms of sailing conditions. The original contribution of this work is the development and application of simple procedures to account for the effect of heading variations, leading to less conservative results in the evaluation of sailing conditions to be avoided. Results are presented in tabular form, reporting the critical speed for which the ship is vulnerable in defined headings, and in polar diagrams, identifying safe sailing conditions for given sea states.