Fatigue
Governing: STCW Code Section A-VIII/1; MSN 1877 (M) Amendment 1 (Merchant Shipping (MLC) (Hours of Work) Regulations 2018); IMO MSC.1/Circ.1598 Guidelines on Fatigue (January 2019).
What fatigue is
IMO's definition: a state of physical and/or mental impairment from inadequate sleep, extended wakefulness, work and rest out of step with circadian rhythms, and physical, mental or emotional exertion, that can impair alertness and the ability to operate a ship or perform safety-related duties safely. It affects everyone regardless of skill, knowledge and training.
The rules
| STCW A-VIII/1 | Requirement |
|---|---|
| Rest in any 24 hours | At least 10 hours |
| Rest in any 7 days | At least 77 hours |
| Division | No more than two periods, one at least 6 hours |
| Interval between rest periods | Not more than 14 hours |
| Emergencies and drills | Rules may be set aside in an emergency; drills conducted to minimise disturbance of rest |
| On call | Compensatory rest if call-outs disturb normal rest |
| Records | Daily hours of rest kept in a standard format, in English and the working language; the seafarer receives an endorsed copy |
| Watch schedules | Posted where easily accessible |
| Alcohol | Not greater than 0.05% BAC or 0.25 mg/l in breath on designated duties |
MSN 1877 applies the same limits to UK ships under the 2018 Hours of Work Regulations. Administrations may allow limited exceptions (for example, 70 hours in 7 days); these are for the flag to authorise, not the yacht to invent.
Worked check: 0700-2300 work, 2300-0500 rest, 0500 onwards work. In the 24 hours from 0700, rest = 2300 to 0500 = 6 hours. That is below the 10-hour minimum, and the next interval from 0500 would run into the following night. Non-compliant.
Sleep
MSC.1/Circ.1598 explains:
- Quantity: on average seven to eight hours of good quality sleep per 24 hours.
- Continuity: six one-hour naps are not the same as one six-hour sleep.
- Sleep debt builds over consecutive days, and the sleep-deprived lose the ability to judge their own impairment.
- Sleep inertia after sudden waking can last more than 30 minutes; the 0300 call to the bridge needs a moment before decisions.
- The window of circadian low is typically 0300-0500, with a smaller post-lunch dip at 1500-1700. Maritime incidents cluster between midnight and 0600.
Signs
The MCA guide lists degraded vigilance, narrowed attention, forgetfulness, more risk-taking, slower or poorer decisions (often without awareness), irritability, withdrawal and odd behaviour.
Yacht realities
Charter turnarounds, late guest nights followed by early starts, deliveries with thin crews, and shipyard periods with long days all push rest to the limit. The records must be true. Falsified rest hours are an offence and hide the risk they were meant to reveal.
WARNING — Guest nights Interior crew working until 0200 and then serving breakfast at 0730 are outside the rules, and so is the deckhand who drove the tender. Rotas must account for it.
TIP — Look after yourself Protect your main sleep period, use short naps sensibly, limit caffeine near sleep, and say when you are too tired to stand a watch safely.