Intact stability operational measures: Criteria, standards and examples

Harmonised treatment of design and operation is very efficient to provide a required safety level. However, operation is usually not addressed by intact stability rules of IMO or classification societies. A substantial change was introduced in the second-generation intact stability criteria of IMO, which address both design requirements and ship-specific operational measures. Moreover, this is done using the same criteria, standards, and safety level, so that operational measures can be used as a loading condition-specific alternative to design assessment. This paper proposes several operational measures, discusses relevant criteria, and defines corresponding acceptance thresholds. Further, it is discussed whether operational measures can always be acceptable as an alternative to the design assessment, when operational measures should be prepared, and how cross-sea and ship propulsion and steering abilities can be addressed. Examples of the proposed operational measures are shown for five ships.