2. Intact stability
Nonlinear ship dynamics in intact condition is one of the fundamental research topics when dealing with ship safety. Indeed, when comfort or operability are of concern, linear (or weakly nonlinear) approaches are typically sufficient. Instead, when the goal is to address the safety of the vessel in adverse weather conditions, large amplitude motions (particularly roll) are to be taken into account, with the consequent need of properly accounting for, and modelling of, (often strongly) nonlinear effects. In the past, nonlinear ship dynamics was often considered as an almost purely-research topic. However, with the increase of the computing capabilities and the advances of the research, this topic has transferred knowledge and tools also to the design and operation of vessels, as well as to the regulatory framework.