A discomfort threshold for impulsive whole-body vibration on a slamming-prone vessel

This study contributes towards a threshold for the onset of discomfort stemming from vibration that is transmitted to the human body by means of impulsive wave slamming in dynamic shipping environments. Wave slamming is a random, violent, non-linear event. Subjective and objective data were collected from two research voyages on a slamming-prone vessel. Full-scale vertical acceleration measurements were conducted near work and accommodation areas on the vessel. A daily diary survey was used to gather human responses among passengers. In addition, instantaneous slamming vibration comfort ratings were obtained by observers on the ship Bridge during a test sequence that purposefully induced slamming. The results indicate that two different approaches converged to the same VDV_1hr comfort threshold (0.41 m/s^1.75 and 0.43 m/s^1.75), which corresponds to the limit where 50% of respondents indicated discomfort. A similar analysis using the r.m.s. metric converged to an identical threshold (0.03 m/s²), irrespective of the accumulated time of assessment.