Ship Gyroscopic Roll Stabilisation

Abstract A thorough understanding of the interaction of waves with ships is a vital factor in the safe and economical technology design. Considerable advances have been made recently in the modelling of wave hydrodynamics and wave-structure interaction. Wave diffraction analysis using 2D Strip Theory (ST) or 3D Boundary Element Methods (BEM) based on potential flow theory is now standard with linear and second-order theory in the frequency domain. In case an assessment of a new ship roll stabilisation system of the gyroscopic type is seen as desirable, no ready to use numerical tool to predict the performance of the wave-structure interaction is available. Therefore, for smaller vessels with a certain advance speed, such a patrol boats or pleasure crafts further developments must be applied to a BEM method to take into account speed corrections plus a standard ST tool in order to include the roll stabilisation effect that could be attained using a dedicated gyroscopic roll stabilisation system installed aboard. In this framework, the proposed work consists of exploring the application of an adapted BEM method with speed corrections, plus a standard ST to study the wave-structure interactions of an unstabilised ship and a ship fitted with a Gyroscopic Roll Stabilisation (GRS) system by considering the case study of a small patrol boat in a seaway. The main objective of this study is to assess the performance of this GRS concept and calculate the operability index of this class of vessels (percentage of time the vessel complies with user pre-defined limiting criteria) for a certain design point using long term statistics, so that complex non-linear responses in waves will be neglected at this stage.