Stress and strain among merchant seafarers differs across the three voyage episodes of port stay, river passage and sea passage

BACKGROUND: A sea voyage is characterized by a variety of work requirements for the ship's crew, basically reflected in three voyage episodes: port stay, river passage and sea passage. The primary aim of this study was to compare stress and strain amongst a sample of merchant seafarers across these three voyage episodes.

METHODS: In a cross-sectional maritime field study, 323 sailors on 22 container ships were biometrically surveyed and completed a questionnaire. In addition, a survey of energy expenditure and heart rate (variability) was carried out in parallel with 236 participants with the SenseWear armband monitor and the RS 800 polar watch.

RESULTS: Port stay and sea passage each accounted for the largest proportion of the ships' journeys, each at around 40%. The study participants rated port stay with 37.8% as the voyage episode with the highest strain, followed by the river passage (24.8%) and then the sea passage (13.0%). The working time during the sea passage was on average shorter than during port stay or the river passage (p<0.001)-as a result, seafarers had more spare time to spend on leisure and sleep. Total energy turnover and, by trend, work energy turnover were notably at the lowest during the sea passage. In particular, the crew had a significantly lower heart rate during the sea passage than during the other two voyage episodes (p = 0.001). Furthermore, there was no difference in the seafarers' heart rate variability between the voyage episodes.

CONCLUSION: In the present study, it becomes clear that an accumulation of psychophysical stress takes place during port stay and leads to a subjectively and objectively higher strain level. In contrast, seafarers are more likely to recover during the sea passage. This knowledge should be used to offer ships' crews targeted health measures, in particular during the sea passage.