When the US National Transportation Safety Bureau (NTSB) investigated the worst man-made environmental disaster at sea (EXXON VALDEZ) it concluded that the company had not adequately considered the significant increase in workload caused by minimum manning. 11,000 square miles of ocean were covered in crude oil, causing economic collapse, suicides and billions of dollars in damage. The cause - fatigue.
None of the three crew members on the bridge had been allowed to take their mandatory six hours off duty before their next 12-hour shift for many weeks.
Despite the inevitable findings, reduced staffing is one of the most widely used methods of reducing crewing costs and raising efficiency. In positive ways this reduction can be achieved through increased automation, however it often falls to crew members to work in their off duty time at expense of health and safety.
How Much Can You Take?
The desired outcome of reduced manning is increased efficiency, but this can be only achieved when safety is not compromised. Fatigue leads to an increased probability of mistakes, so a balance between over- and under-manning must be established.
What causes fatigue and stress?
* Workload: The higher the workload the more recovery time is needed. Tools and equipment in use and current procedures influence the workload
* Perceived risk or interest: Stimulation of the senses (pleasure or fear) allows longer alertness
* Diet: A bad diet can influence concentration and stress resistance. One liter of water in your body less than it needs (e.g. through sweating) can lower your IQ test score by 30%
* Low Fitness
* Time of day: Humans are animals with a fixed day and night rhythm. We are less alert between 3am and 5am.
Much was learned about fatigue and sleep deprivation thanks to the thorough investigation of the EXXON VALDEZ disaster. The UK’s Marine Accident Investigation Branch (MAIB) stated that 82% of all groundings, which are due to fatigue, happen between 2 am and 6 am.
A Case Study
The current practice of six hours on/ six hours off duty makes it impossible to complete all jobs within the given time. The Human Element in Shipping provides us with the case study involving the accident of the ANTARI cargo vessel, whose watch keeper fell asleep and grounded the ship.
An investigation revealed that the Master and the Chief Officer had been significantly overworked during the previous two months, amassing a huge debt of sleep.
Vessels with less than three officers are especially endangered, as their attention is required constantly for port calls, preparations, cargo operations etc.
How to Stop Fatigue
Since a number of combined factors cause fatigue, the solutions are divided into design and operational considerations:
* Brighter lightbulbs: It has been found that normal ship lighting is not bright enough to help fight sleepiness during the nightshift
* Reduce the level of ship noises; they disrupt the important REM sleep phase
* Reduce vibrations; they can cause stress and aggression, and can affect blood pressure and heart rate
* Reduce the ship motion; pitching and rolling can disrupt sleep pattern
Most readers will be aware that the rules demand a minimum rest time of 10 hours within any 24-hour period, which also applies to the 2x6 hours model. But are those rules being followed? Here are some interesting facts taken from the guide (p. 52)
* Two-thirds of all seamen work four weeks on/four weeks off
* Most of them need three days to adjust to the change (both ways)
* 50% of seafarers work 12 hours on/12 hours off, and 25% work six on/six off
* People who get less than six hours of sleep per day over 14 consecutive days suffer a measurable performance deficit
* The probability of an incident is twice as great in a 12-hour shift as in an eight-hour shift
* Up to 40% of seafarers think they are a danger to themselves or to operations due to their working hours
* Naps can reduce the rate of incidents by up to 50%
Most seafarers think the most effective ways of reducing fatigue are to increase manning and reduce paperwork – rather than to increase leave or introduce tougher laws.
While the above facts are interesting to know, the real problem remains: many companies pay lip service to rules and regulations instead of implementing effective changes to avoid fatigue.
The guide continues with a list of effective measures which can be implemented to improve both effectiveness and safety. These measures are combined with a fatigue management plan which includes the participation of all stakeholders: the seafarer, the ship manager and the master.
The ship manager is requested to ensure: adequate hand-over time on crew changes, adequate voyage length, time in port and service time. In addition, he is requested to eliminate social and language barriers and to communicate the ISM code requirements very clearly.
The master will ensure adequate family contact, shore leaves, workload, effective work/rest arrangements and nap time. Furthermore, he will create an open and just culture for reporting fatigue and he should Implement a rotation for high and low demand tasks.
In return the seafarer needs to arrange adequate sleep by ensuring a healthy lifstyle, for example avoiding alcohol before sleep and taking strategic naps. The seafarer is also requested to perform accurate self-monitoring.
These points can improve awareness of the dangers of fatigue. Most of the time even an exhausted crew will get the ship into harbour, but accidents are more likely, as as the EXXON VALDEZ proves. And it remains that the risk and consequential costs are likely to be much higher than the savings achieved through reduced manning.