Multidisciplinary experiment using steep regular waves to determine ship operating conditions that avoid capsize

Abstract

This paper explores using steep regular waves to identifying safe operating conditions that avoid capsize. The data is from a multidisciplinary experiment using an autonomous scale-model running a proportional-derivative controller in aft of beam steep regular waves. The test explored relative wave headings from 15 • to 75 • and speeds from 0.1 to 0.4 Froude number. This effort analyzes the resultant ship trajectories to determine if the model obtained the desired operating conditions during each run. For slow speeds, safe operating conditions could not be identified since the requested headings could not be achieved. For moderate speeds, most requested headings could be achieved. At the highest speeds, only relative wave headings closer to beam seas could be explored as the model capsized in stern quartering waves. Results show that wavelength and wave steepness have minimal effects on the model's ability to achieve a desired heading. Finally, only a limited number of runs are required to verify a safe operating condition since capsizes appear to be consistently repeatable. This research highlights the usefulness of using steep regular waves for capsize testing but also some of its limitations.