Fatigue at sea
Lützhöft, M., Thorslund, B., Kircher, A., Gillberg, M.
Result and recommendations for managing fatigue in watch systems onboard
This document presents the main results and recommendations from the project Fatigue at sea. It is meant as a living document, where
mainly columns should be filled in with suggestions of who should take action to enforce these recommendations, and how this is to
The following is suggested by the results of questionnaires and diaries:
• Mates in the three-watch system are more satisfied with their working times and working situation. • Mates in the two-watch system are sleepier than the mates in the three-watch system, especially in the early morning and
• Most mates think they need at least eight hours of sleep per day, independent of watch system.
• All mates are less sleepy and less stressed at home, independent of watch system.
The following is suggested by the results of EOG, KSS and reaction time tests:
• Although no statistical difference is found, all tendencies in the results point in the same direction: officers in the 6x6 system
are more tired than the officers in the 4x8 system.
• The highest KSS ratings show that all work performed over and above the six hours lead to very high sleepiness levels and
• KSS values are highest on night shifts. • 5.6 % of all scorings are 7 (out of 9) and above. This means that during 83 hours participants were tired. During 39 hours they
were very tired, staying awake with effort or fighting sleep.
• 82 % of the very high KSS values (above 7) is from ships with the 6x6 system.
• The sleepiest participants work two-shift.
• Reaction times are longer for all participants after a night shift. • Variation in reaction time is higher for two-shift which suggests that they are more unfocused.
• Actiwatch data show that participants sleep approximately six to seven hours per 24 hours independent of shift system.
• The sleep on the two-watch ships is divided into two sleeps, very few of which is longer than approximately 4.5 hours. The
only watch in the 4x8 system which approaches these low levels seems to be the 04-08/16-20 watch.
• Sleep quality is low and can probably be classified as disturbed, for both shift systems according to Actiwatch results.
• Non-Swedish participants rate their sleepiness (KSS) significantly lower but also have significantly longer reaction times after
the night watch, which is contradictory.
The following conclusions may be drawn from the interview study:
• Most Swedish shipping companies do not think fatigue is a problem (during normal conditions) – but would address it if they
• Most would consider fatigue monitoring equipment and believe that the crew would accept it.
• All would install equipment if insurance premiums were lowered (say 30 %)
Working more than 2x6 hours per 24 hours should be avoided since this lead to very high levels of sleepiness. There should always be
two persons on the bridge during watch keeping. This conclusion indicates difficulties with a continued use of the two-watch system
on ships with only two nautical officers.
A mutual effort with commitment on all levels is a prerequisite in order to accomplish a change and an improvement. A survey of
existing recommendations shows that most of them are directed to the ship and to individuals onboard. Only seldom do the
recommendations address the shipping company or other land-based organisations or authorities. A selection of recommendations is
presented below, with columns showing what stakeholders can and should do.
There are individual differences between people, which means that not all need the same amount of sleep. The recommendations,
however, are of a general nature. One example is that older, more experienced officers are better at staying awake, at judging their
fatigue levels and at judging and compensating for any possible performance decrement due to fatigue, than young people are. On the
other hand it is more difficult for older people to sleep during the day
It is also important to have a systematic approach when considering recommendations. Some people onboard might experience a
change to the worse, e.g. the cook steward if watch and meal times are changed or a mate who gets a few hours watch during the
night, but the crew as a whole will be more alert.
Technical solutions are available that wake a sleeping person but do not prevent an officer on watch from becoming tired or assist in
decision making when the personal capacity is impaired due to fatigue or being newly awakened. Equipment that gives off a warning
when someone is too tired or is falling asleep is under development, for example motion detectors or cameras, but the equipment will
not make sure that thoroughly rested personnel is available to take over. This has to be controlled at an organizational level. If watch
keeping can be upheld with rested personnel an investment in technical solutions is obsolete. Recommendation Onboard
(Shipping National authorities
solution but rather a way of highlighting the problem. Can be used for prevention and investigation of accidents.
filling). Co-ordinate vetting. Review of what is necessary at moorings etc.
understood. Repeating order and actions give a possibility to control both a person’s actions and state. Decision making, troubleshooting. It is important to make sure the look-out have interesting
tasks and that the person’s competence is utilized in the forming of a bridge team.
consideration watch system and biorhythm at time zone change.
in. Sleep the same time every day if it is shorter than eight hours (“anchor sleep”).
o Food o Exercise o Stimuli o Light o Socially (and at
Remember that a person straight out of bed is not sharp.
More information and further reports are available at Questions and comments can be directed to Margareta Lützhö
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