Watch systems at sea have been the same for a very long time, but surveys suggest that there are better solutions. The effects of different relief systems will now be reviewed in a new research study.
Ten years ago the Swedish Navy carried out a project to study how different re-lief systems affected levels of tiredness on board. The results showed that crews were significantly more alert when they were relieved at 9.00 and 15.00 compared with the traditional four-eight watch. Those who had previously worked eight-twelve watches were slightly more tired after the change, while those who worked twelve
to four were more alert. Overall alertness among crew members increased significantly.
A new watch relief project will soon be started with employees of the merchant navy. Wessel van Leeuwen at the Stress Research Institute, Stockholm University, is one of the participants.
”We are going to examine all the different watch systems to find out which works best,” he says. ”We will look at how people are affected at the crew level and the individual level, but in the end there must be some form of compromise for the system to work.”
The most widely criticised watch system is six-on six-off. Several studies have shown high levels of tiredness on board two-watch ships, and these ships are also over-represented in accident statistics. Last year an attempt was made to introduce extended relief times on two-watch ships, where the crew could choose to work eight hours on and 8 hours off.
”All the seamen who took part thought it was much better to work eight-on-eight than six-on- six,” says Wessel van Leeuwen.
They were more alert and felt better in general. But according to international regulations it is not permitted to work eight-on-eight because it means 16 hours’ work on some days. The 35 participants in the survey first worked three weeks of six-on six-off. They were then free for three weeks, and worked the same period with eight-on-eight watches. The survey was carried out on five dredging ships in British waters, with permission from the UK Maritime Cost Guard.
How you can improve your sleep
Regular exercise: Most people sleep better if they exercise. It produces natural tiredness, at the same time as it reduces the risk of stress, anxiety and depression.
Relaxation: Sleep problems are often associated with stress and anxiety, and a lack of sleep contributes to higher stress levels. If you find it difficult to calm down, relaxation exercises may help. You can find some examples of these at www.1177.se, Vårdguiden (care guide).
Diet: Avoid rich or spicy food before going to bed. The rate of digestion decreases when you sleep and it can be difficult to relax if you go to bed directly after a large meal.
Avoid alcohol and nicotine: Smokers often find it more difficult to sleep and wake up more frequently during the night than non-smokers. Alcohol contains large amounts of calories. It may help people to relax initially, but it often leads to disrupted sleep.
Naps: If you can, take a nap during your break. Try not to sleep for more than half an hour, though. Then there is a risk that you fall into deep sleep, and it can take some time before you wake up properly.