Development of Seakeeping Test and Data Processing System

A seakeeping test and data processing system is developed for towing tanks. This system includes two main procedures: wave-generating and data processing. In the wave-generating procedure, the linear filtering method is used to generate irregular waveswith the full consideration of the actual efficiency of the machine and the compensation for the actual stroke of piston. Furthermore, groups of piston motion data meeting the requirements of target spectrum are afforded. To ensure the normal operation of a wave machine, the above data within the range of the rated strokes of piston should be chosen. In the data processing procedure, the correlation function method is used to handle the time domain signals which contain irregular waves, ship swaying motion, hull stress and so on. Then the spectrum curve of these test data can be drawn and some statistical values can be obtained based on the narrow-band spectrum theory. According to these statistical values, the frequency response function can be derived, and the predicted value of ship motion in irregular waves can be calculated. By comparing the predicted and experimental results, the reliability of this system can be evaluated. On the basis of the movement of a boat in irregular waves and a series of dynamic responding experiments, this paper proves that the developed system has many advantages, such as succinctness, completeness, accurate data process, reliability, accurate simulation from actual spectrum to target spectrum and soon.