Six Hours On, Six Hours Off Watch Roster Is ‘Most Tiring’

The most far-reaching study into working patterns and fatigue at sea has produced some worrying results with firm evidence that the regular six hours on, six hours off watch roster is the most tiring and potentially dangerous, regularly causing seafarers to sleep while on duty.
The European Union (EU)-backed Project Horizon used simulators at Warsash Maritime Academy and Chalmers University in Gothenburg to create real- life working situations and voyage plans in the hope of coming to a scientific understanding of fatigue at sea.
The study was mainly based on the common six hours on, six hours off and the four hours on, eight hours off working patterns
During watch periods, the report found: “In all four watchkeeping subgroups there was evidence of full-blown sleep. Incidents of sleep mainly occurred during the night and early-morning watches.
“Falling asleep on the bridge is a main indicator of the effect of the watch on dangerous states of the crew. Participants in all the groups reported high levels of subjective sleepiness, close to danger levels for car drivers.”
The study found that those seafarers on a six-on, six-off pattern got “markedly less sleep” compared to those working four on, eight off. Performance was also badly affected with those officers whose off-watch periods were disturbed showing the biggest deterioration, increased stress and “significantly high levels of tiredness”.
The study found: “Process Verification Tests (PVT) of reaction time, carried out at the start and end of each shift, showed clear evidence of deterioration.
“The slowest reaction times were found at the end of the night watches and among those on the six/six pattern.”
Researchers say the findings of the study will allow fatigue to be managed more safely by identifying the times and situations in the working day when fatigue is likely to be the most severe.
“Project Horizon findings suggest that owners, regulators, seafarers and others should pay special attention to the potential risks in difficult waters in combination with the six/six watch system [because of sleep loss], night watches, the last portion of most watches [especially night watches], and watches after reduced sleep opportunity,” it warned.
Project Horizon has now devised a computer-based “Fatigue Management Toolkit” called Martha, which it thinks can help managers spot dangerous situations and work to avoid them.
As well as the two maritime universities, the Horizon Project also involved Bureau Veritas, the European Transport Workers Federation, the Stress Research Institute at Stockholm University, the Standard P&I Club, the European Community Shipowners’ Association, the European Harbour Masters’ Committee, Intertanko, the UK Maritime Accident Investigation Branch and the European Maritime and Coastguard Agency.