Implications of the second generation intact stability criteria when applied to a NZ offshore patrol vessel

To address the problems of dynamic stability failures, the International Maritime Organisation plan to supersede the intact stability criteria. The draft criteria have been applied to a New Zealand naval patrol vessel to aid in understanding the implication imposed by the revised criteria. This paper addresses how the criteria were applied to the vessel and presents the outcomes of the calculated vulnerabilities. A computational simulation was conducted for the broaching phenomenon using four possible phenomenon-inducing wavelengths. It was found that the patrol vessel broached by more than fifteen degrees over a seven second time period. Therefore, taking into account the simplifications of the analysis, the OPVs, like other vessels, could be deemed vulnerable to the surf-riding and broaching-to phenomenon for these given, operationally avoidable, encounter conditions. Further analysis is recommended when the draft criteria is finalised.