The natural roll period is an important component of stability assessment. The need for development of a proper estimation method is particularly important for river-sea ships, which represent inland vessels intended for operations in maritime environment. The overall goal of this study is to contribute to the development of a suitable method for the natural roll period estimation for river-sea ships. For this purpose, a method based on the linear potential hydrodynamics is applied on a database consisted of 31 river-sea ships. The obtained results are analysed and compared with those calculated using semi-empirical methods, and a practical natural roll period estimation method for river-sea ships is proposed.
