ABSTRACT

The paper deals with the characteristics of the equivalent metacentric height of ships which governs the frequency of the resonance mode of ship motion called the synchronous roll. The frequency of synchronous roll can be effectively predicted on the basis of the equivalent metacentric height which is amplitude of roll depended. This frequency can be considerably different than usually estimated with the use of the initial metacentric height. The analyzed problem covers the need for realistic assessment of the range of variation of this equivalent metacentric height. Ship operators should be aware of significance of the expected GMeq changes, since consequently the frequency of potentially dangerous synchronous roll occurs at different wave encounter frequency than predicted on the basis of the initial metacentric height GMo recommended nowadays by IMO for the routine on-board use. Numerous ships in their typical loading conditions are studied to obtain the basis for statistical analysis of the equivalent metacentric height variation.