Human science is a rarity in the merchant marine domain, there is nothing equivalent to the US Navy’s excellent TADMUS programme, so the release of preliminary findings of Project Horizon are welcome. Undoubtedly its release will be met with “we knew that already” but its real value is putting number to what was already known, or suspected, and giving less wriggle room on the issue of safe manning – a markedly different issue from minimum manning – at the expense of seafarers being imprisoned for falling asleep on a poorly manned bridge.
The results of program, which involved 90 volunteers of a mix of nationalities and gender reflecting current ship manpower, under realistic living and work conditions, in a variety of simulators at Warsash and Chalmers, are chilling by not unexpected.
Says the prelimary report: “In all four of the watchkeeping sub-groups (4/8 and 6/6 at Chalmers and 6/6 deck and engineers at Warsash) there was evidence of full-blown sleep. Incidents of sleep on watch mainly occurred during night and early morning watches. At least one incident of microsleep was detected among 40% of team 1, 4/8, at Chalmers (the 0000-0400 watch), around 45% of team 1, 6/6, at Chalmers (0000-0600 watch) and around 40% for team 2, 6/6, at Chalmers (0600-1200 watch). At Warsash the rates varied from more than 20% of the 1800-0000 watch to 0% of the 0600-12000 watch. Falling asleep on the bridge is a main indicator of the effect of the watch on dangerous states of the crew”.
Key findings include:
- at least one occurrence of sleep was detected among 45% of officers in the 6/6 team working the 0000-0600hrs watch at Chalmers and one occurrence for about 40% of those on the 0000-0400 watch in the 4/8 pattern
- at Warsash, where the watchkeepers remained undisturbed in their off-watch rest periods, the number of occurrences of sleeping on watch for officers on the 6/6 pattern varied, and was up to more than 20% on the 1800-0000 watch
- such incidents of sleeping on watch were found within both watchkeeping patterns, and they mainly occurred during night and early morning watches
- participants in all the groups reported relatively high levels of subjective sleepiness on the KSS scale, which got higher towards the end of a watch and the end of the week
- varying degrees of sleep loss were observed between the watch systems and depending on whether off-watch periods were disturbed or not. Overall sleep duration for those on the 4/8 pattern was found to be relatively normal, with around 7.5 hours a day for those in team 1 at Chalmers and about 6 hours for team 2
- participants working 6/6 watches were found to get markedly less sleep than those on 4/8, and data showed a clear ‘split’ sleeping pattern in which daily sleep on the 6/6 pattern was divided into two periods — one of between three to four hours and the other averaging between two to three hours
- reaction time tests, carried out at the start and end of each watch, showed clear evidence of performance deterioration – and the slowest reaction times were found at the end of night watches and among those on the 6/6 patterns
- watchkeepers were found to be most tired at night and in the afternoon and sleepiness levels were found to peak towards the end of night watches
- the 6/6 regime was found to be more tiring than the 4/8 rotas and ‘disturbed’ off-watch periods were found to produce significantly high levels of tiredness
- in both watch systems, the disturbed off-watch period was found to have a profound effect upon levels of sleepiness
- there was evidence that routine and procedural tasks could be carried out with little or no degradation, whilst participants appeared to find it harder to deal with novel ‘events’, such as collision avoidance or fault diagnosis, as the ‘voyages’ progressed
- researchers also noted a decline in the quality of the information being given by participants at watch handovers as the week progressed
An obvious conclusion is that having a single watchkeeper at night is not a great idea, although it makes good commercial sense. It is not surprising that routine procedures were little affected by fatigue but performance under developing and high stress situations were degraded.
Data from Project Horizon indicates that the probability of danger at sea will be highest when night watches are combined with prior reduction of sleep opportunities, combined with passages through narrow or very densely travelled waters, or during reduced visibility.
The 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 6/6 watch system (because of sleep loss), night watches, the last portion of most watches (especially night watches), and watches after reduced sleep opportunity.
A variety of methods (some of which are already commonly deployed) may be used to address this potential risk, including alarm systems to alert crew before important waypoints, encouragement not to use chairs on the bridge during night watches, additional crew, training crew to recognise symptoms of fatigue, and special protection of sleep periods for watchkeepers.
This has led to the development of a fatigue risk management toolkit called Martha. The computer-based system will provide an interface with selectable watch schedules and a ‘do-it-yourself’ watch system facility. Users will be able to enter their working schedules over a six-week time window and receive predicted estimates of the most risky times and the times of highest potential sleepiness for each watch and for the whole watch schedule, as well as for time outside watch duty.