Experimental Study of Large Amplitude Motions of Containerships in Waves (Containerships in Waves)

Duration: 1997-1999

Coordination: Canal del Pardo

Partners: Instituto Superior Técnico

Funding Entity: EU - Programme Large Scale Facilities

An experimental programme was carried out at the Laboratory of Ship Dynamics of El Pardo Model Basin, Madrid. The objective was to obtain the vertical responses of a containership in non-linear conditions, meaning that the waves were of large amplitude in order to induce non-linear responses. The data would serve to calibrate and validate a theoretical and numerical procedure. The researchers were particularly interested in the asymmetry of the responses, specially the loads, and the influence of the wave steepness on the non-linear behaviour. This way the tests were carried out in regular head waves, for two Froude numbers (Fn=0.15 and Fn=0.25), and for several wave lengths along the range of interest. For each wave length four wave heights were tested. Some tests were also carried out in irregular waves with several significant wave heights and mean wave periods. A three-part segmented model of a containership was wooden manufactured. The cuts were placed at midship and a quarter from the bow. A rigid bar fixed to the model along its length connected the segments. Strain gauges were mounted on the bar at midship and a quarter from bow, prepared to measure the vertical shear force and bending moment at these positions. The vertical motions at three positions along the ship length were measured by potentiometers. Accelerometers were installed at stations 20 (bow), 15, 10, 5 and 0. The relative motions were measured by capacitive wave gauges fixed to the sides of the model at stations 20, 18, 10 and 2. In addition, one more wave gauge was installed on the bow deck to identify and measure the height of water on deck. Finally, a wave gauge measured the wave elevation close to the bow of the model. Part of the experimental data has been analysed, which resulted in one publication (Fonseca and Guedes Soares, 1998).

Project Team

Associated Publications