Managing crew fatigue

Managing fatigue is everybody’s responsibility, both morally and legally. This guidance will help you manage fatigue.

Owners and masters must take all practicable steps to make sure the vessel and people are safe. Owners must involve crew in the management of fatigue and the risks to safety.

What is fatigue?

Mostly it is lack of sleep

Fatigue is a state of weariness because of working for too long, working against your body clock, heavy physical or mental workload, insufficient rest or inadequate sleep. Fatigue can develop quickly, for example if you are doing heavy lifting. But it can also develop slowly, for example if you lose an hour of sleep a few nights in a row. The environment you work in and what you eat and drink can influence how quickly you start to suffer from fatigue.

What happens when you are fatigued?

Fatigued people are very likely to make mistakes.  The effects of serious fatigue are comparable to being over the drink driving limit: poor judgements, slow reactions, poor memory, impaired vision are some of the signs. Fatigue is a factor that significantly increases the risk of accidents. Long term exposure to fatigue is associated with health problems—such as obesity diabetes, and heart disease.

What causes fatigue?

Lack of sleep

Generally, people need between 7-9 hours of sleep per night to perform adequately and effectively. Any less than this can be a problem. Most accidents caused by fatigue follow a lack of sleep or poor-quality sleep. Poor-quality sleep is when your sleep is disturbed, eg by light, noise, motion, alcohol or drugs. Fatigue can also accumulate when you do not get extra sleep to make up for lost sleep.

Body clock disruptions

Our body clock naturally programs us to be asleep at night. There is also a natural tendency to not be so alert in the middle of the afternoon. This means that when you work during the night you must consider your body clock and plan when your sleep times are during the day.


Common features of work that lead to fatigue are a long work day, physical work, boring or repetitive work, few or no breaks, a pay system that encourages long hours, not allowing enough time for sleep, unpredictable work schedules, sleep opportunities during natural times of high alertness and mentally demanding tasks.


The maritime work environment is stressful on seafarers and can make fatigue from lack of sleep worse. Common environmental stressors on seafarers are cold, vibration, heat, noise and ship’s motion.

Lifestyle and home

Seafarers have to balance work, lifestyle/home and sleep. Often lifestyle and home demands come ahead of sleep, making them a cause of seafarer fatigue. Common lifestyle and home demands are commuting, time with family and friends, family routine disrupting sleep, jobs around the house, another job, time to do your own thing, alcohol, stress, medication.

How do I manage fatigue?

We need to sleep

The answer to fatigue that builds up over a few nights (cumulative fatigue) is easy—SLEEP. There is no other answer.

Other conditions, like heat or long physical work, can make fatigue caused by lack of sleep worse. But accidents are usually linked with lack of sleep.

Understanding how the body’s need to sleep works is the starting point for managing fatigue. The need to sleep is built into our bodies in two ways: the need for recovery after being awake for a while and our body clock. People are designed to spend about a third of their lives sleeping. If we don’t sleep our performance and health suffers.

Planning your time and sleep: Seafaring can be demanding, leaving little time for other activities. Family and friends need time, seafarers often commute and there is still a need to sleep. Sleep time is often traded off. This happens because often others do not understand your need for sleep when you are working shifts or long hours. To get the best sleep deal, you should plan with others how they can help you protect your sleep period.

The need for recovery

After being awake for a while, our bodies and brains do not function as well. Sleep is needed to recover from all the things we do when we are awake. Most people sleep about 8 hours a day when they have the opportunity to do so. So, after being awake about 16 hours we are naturally ready to go to sleep. While we can continue to stay awake, the chances of something going wrong increase, as time passes.

There are a number of practical tools that can be used for assessing whether fatigue may be a problem in your work.

The below table provides guidance on risk times for fatigue .

Risk of fatigue increases when...
Work hours per week are more than 60 hours
Work hours per day are more than 12 hours 
Rest hours between work periods are less than 7 hours
Night work per seven days (between 9 pm and 9 am) are 4 or more
Short breaks within work period (10 minutes) there are no breaks
Recover days (per 7 days) is less than 1 day

Related information

Last updated: 

Friday 12 June 2020