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Fatigue and the Watch: 31.5% of Groundings, the Rest Rules and What Actually Helps

🕑 5 min read words Mlc • Human-element • Safety

Sources: Nautical Institute study with the University of Strathclyde (as supplied); MAIB reports; IMCA SF 21/22; TSIB report on VIYADA NAREE (rest rules); Large Yacht Code LY3 section 26
The number: 31.5% of grounding investigations in the IMO’s GISIS database cite fatigue (186 of 590)
Relevant to: every seafarer who stands a watch

The Numbers

The Nautical Institute, working with the University of Strathclyde’s Maritime Human Factors Centre, has told the IMO that 31.5% of grounding investigations in the IMO’s GISIS casualty database cite seafarer fatigue: 186 of 590. For UK groundings investigated by the MAIB between 2010 and 2025 the figure is 33.9%. The same study found fatigue recorded in 62 of 244 collisions (25.4%) and 37 of 351 onboard fires, explosions and occupational accidents (10.5%). These figures come from the Institute’s own announcement and we have not seen the full report.

The Rules

The minimum rest requirements under STCW and MLC 2006 are, for any seafarer on watch duty:

not less than 10 hours of rest in any 24-hour period, and not less than 77 hours in any seven days;
rest may be split into no more than two periods, one at least six hours long;
the interval between consecutive rest periods must not exceed 14 hours.

Exceptions exist for emergencies and drills. The Large Yacht Code (LY3, section 26) states that fatigue at sea is a serious safety issue and that vessels should be sufficiently manned to avoid excessive hours. Records must be accurate.

What The Cases Show

Crystal Stream. The skipper, the only person awake, fell asleep at the helm. He had managed just over four hours of rest in the previous 24. The wheelhouse watch alarm was not connected to the autopilot.
Sustain. About 18 hours of accumulated sleep debt, a skipper who felt tired and said that was normal at that point in a trip, and a 7.7-knot grounding.
Silver Cloud II. A skipper who was ill and judged himself fit, working 16.5- to 18-hour days against rest in fragments of three, four and six hours.
IMCA SF 21/22. A Mate fell asleep on a calm night watch after about 29 hours worked in 48. Logs filled in once a week. No ECDIS alarm set.
Exxon Valdez. Fatigue and a single-officer watch are among the tags on our case.

Why Records Matter

In several cases the work and rest logs were filled in to look compliant rather than to say what happened. If the log says the rules were met, the company sees no risk. An honest log is the only way fatigue is ever managed instead of hidden.

What Helps On The Watch

Know the signs. Heavy eyes, drifting attention, re-reading the same line, not remembering the last few minutes. These are the signs a micro-sleep is close.
Act, do not push through. IMCA’s advice from SF 21/22: stand up, move around, call a deckhand to the bridge or call the Master.
Use the safety net. A watch alarm connected to the autopilot. ECDIS and depth alarms set.
Treat quiet nights as higher risk, not lower. Calm sea and a monotonous passage are when it is easiest to drift off.
Tell the Master. Not being fit for a watch is a safety report, not a failing.
For the Master and company: plan the work around rest, do not rely on the log, and do not make being unfit a thing to hide.

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