The Induced Forces and Motions of a Tumblehome Hullform (Model 5613) Undergoing Forced Roll

Abstract : Predictions of large amplitude roll motions and capsize events have proven to be difficult and include large uncertainty. One of the reasons for this is a lack of knowledge of resultant forces and moments for large roll angles. Currently, the equations used by numerical models to predict forces and moments due to roll motion are based on experimental data performed within a small range of roll amplitudes. A data set of forces and moments is necessary to verify that the model predictions are accurate in the upper ranges, or to develop new models to predict the forces and moments for these larger roll amplitudes. In 2005, the Naval Surface Warfare Center, Carderock Division, tested NSWC Model 5613, a tumblehome hullform, with the primary objective of obtaining model scale constrained seakeeping results to provide information necessary to perform verification of surge, sway, heave forces and motions, and roll, pitch, and yaw moments and motions acting on a surface combatant hull during large amplitude motions and capsize events. This report describes the testing and the resultant acquired data and begins to establish a database defining non-linear forces and moments associated with large amplitude motions and capsize events.