Wind Tunnel Assessment of Ship Manoeuvrability using a PMM Technique

Tests have been performed at the Danish Maritime Institute (DMI) to investigate the applicability of a new wind tunnel Planar Motion Mechanism (PMM) for the determination of hydrodynamic coefficients of ships. The method has been tested on a tanker with known towing tank data. The wind tunnel model was a light foam hull equipped with fixed rudder but without propeller. Tests comprised the static drift, pure sway and pure yaw modes in the range corresponding to manoeuvring at forward speed. The resulting hydrodynamic coefficients and values of the stability criterion are compared with the towing tank data giving reasonable results. The dependency of amplitude and frequency is evaluated, and sources of inaccuracy are discussed. It is concluded that the wind tunnel method is a promising method to achieve a fast and cost-effective estimate of the hydrodynamic coefficients of a ship hull. The coefficients can be used for an assessment of whether the vessel will meet given manoeuvrability criteria.