Estimation of broaching probability using wave-induced forces and moments measured in captive model tests

Abstract

Broaching is a stability failure that involves many force components. Wave-induced forces, in particular, play an important role in the estimation of broaching, and it is necessary for these forces to be estimated accurately. Captive model experiments of wave forces in regular waves were, therefore, conducted for tumblehome and flare vessels (the vessels were based on ones developed by the US Office of Naval Research). Empirical correction factors of the wave forces for different wavelength-to-ship length ratios and heading angles were obtained; the difference between theoretical calculations and experimental values obtained in the present were used to develop these factors. These empirical correction factors were then added into a theoretical study and the results from this study were compared with that of a free-running model experiment not only in regular waves but also in irregular waves for both the tumblehome and flare vessels. The results indicate that if the empirical corrections of the wave forces depending on the wavelength are used, then the broaching probability in irregular waves can be well estimated for these two types of vessels.