Correlations of GZ Curve Parameters


  1. Perrault, D.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
Over the decades of the last few centuries the stability of ships has moved from the art of the shipbuilder and master on the realm of regulatory agencies. In that time several concepts for assessing stability have emerged, all rooted in the GZ curve; the curve that defines the relationship between the angle of heel and the moment arm of the righting couple that would return the ship to the angle of static equilibrium, which is usually 0°. Within each concept there are usually several parameters suggested as stability criteria including righting arms, areas under the curve and moments of areas under the curve. Criteria were developed out of expert knowledge and have been supported by good service, but the basis is not clearly documented. Many of these criteria have been observed to be correlated so as to fail to provide additional information or, conversely, to give a different perspective on the same information. This study looks at the correlations between the parameters in the standards used by many navies, including those based on the seminal work by Sarchin and Golberg and those used by the German and Dutch navies (among others). The study looks not only within each set, but looks for correlations between the parameter sets as well. The intent is to gain insight into the parameters and the phenomena they represent, and to identify the optima. Parameter set for regression against probabilistic results of simulations.
GZ Curve;Correlation of Stability Indicators
Report Number
DRDC-RDDC-2016-N056 — External Literature
Date of publication
01 Jan 2018
Number of Pages
Reprinted from
Proceedings of the 15th International Ship Stability Workshop Stockholm Sweden, p. 1-10
Electronic Document(PDF)

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