The operational development of diagnostic seasickness criteria through a human cyber-physical system.

Thresholds that guide diagnoses of probable and acceptable seasickness levels on board ships are scarcely reported in literature. Motion sickness incidence and motion sickness dose value thresholds exist, but are defined for specific environments, such as naval, or offered merely as optional criteria for ship performance metrics. The presented work communicates a novel means of developing seasickness diagnostic criteria during ship operation, based on observations from shipboard measurement systems and seafarers using an innovative platform. The innovative platform provides personalised seasickness criteria that are accessible during ship operation to estimate the probable level of seasickness on board. Results are compared to that from a traditional method of data acquisition and analyses, post operation, revealing a similar trend in diagnostic threshold magnitudes (13-85 m/s1.5) that can be applicable to voyages with different durations (0.5-6 hr) considering desired levels of seasickness (10-50 %). The seasickness criteria are envisioned to be pertinent for the prediction of probable seasickness levels based on sea state forecasts and ship motion estimation.

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 VDV1hr comfort threshold (0.41 m/s1.75 and 0.43 m/s1.75), 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.