Procedure to Obtain Added Mass in Ships From Natural Frequencies Measured in Hull Vertical Vibration Full Scale Tests

This work shows an experimental-numerical procedure used to determine added mass of ships. A numerical Finite Element ship hull model is constructed according to the weight distribution and the drafts over its length during the full scale vibration measurement. The rate breadth/draft for each frame of the hull is considered as the independent variable of a quadratic function representing the added mass distribution, which coefficients are determined in order to minimize the sum of squared differences between the natural frequencies obtained numerically in respect with those obtained in the correspondent full scale measurement. The added mass coefficients obtained from the experimental data of a first ship are then used to predict numerically the natural frequencies of a second ship of the same type.