A mooring line parted and snapped back. The officer was standing in the wrong place.
On 2 March 2015, while the LNG carrier Zarga was berthing at South Hook in Milford Haven, a mooring line under tension parted. The line snapped back across the deck and struck a deck officer, who suffered severe head injuries.
Words in this case
- snap-back
- The violent whip of a rope or wire when it parts under tension.
- to part
- Of a line: to break.
- retirement criteria
- The rules for taking a worn line out of service.
- tension mode
- A winch setting that keeps a set pull on a line automatically.
- mooring station
- The forward or aft deck where the lines are handled.
More words like these in the glossary and in listening practice.
What happened
Zarga is one of the largest LNG carriers in the world. During berthing in strong wind, the mooring winches were heaving on the lines to hold the ship against the berth. One line, made of a modern high-strength synthetic fibre, parted under load.
When a line parts, the energy stored in it releases along a path that is not a straight line: the rope whips back and sideways, and the snap-back zone is larger and less predictable than the old diagrams suggested. The officer supervising the mooring station was hit and seriously injured.
The Marine Accident Investigation Branch found that the line had been used beyond the point where it should have been retired, that the design of the line and the winches allowed very high loads, and that the danger zone at that mooring station was not understood. The report drove new industry guidance on mooring line management and snap-back.
Why it happened
- The line was worn and its strength had dropped; it parted at a load well below what a new line would hold.
- Powerful winches heaving on modern lines can generate loads that break the rope before anybody notices.
- The people at the station stood inside the area the line would sweep when it parted.
What to remember on board
- Snap-back zones are the whole mooring deck, not a painted patch; when a line comes under load, everybody who does not need to be near it is not near it.
- Lines are retired by condition and record, not when they break; inspect, log, and replace.
- Winches in tension mode hold, they do not fight the ship; the officer decides the loads, not the drum.
- Helmet, gloves, and the habit of looking at where the line leads before you step.
What changed afterwards
The industry mooring guidelines (OCIMF MEG4) were revised with new rules on line selection, retirement criteria and snap-back awareness; many companies repainted and re-trained their mooring stations.
Three questions
The kind of questions a knowledge test asks about this case. Keys 1 to 4 answer, Enter goes on.
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Source: Serious injury to a deck officer when a mooring line parted on board the LNG carrier Zarga, Milford Haven, Marine Accident Investigation Branch (UK), report 2017. Find the report.
On this site: Gas carriers ยท Mooring vocabulary in the glossary.
Plain-English summary of an official investigation report. Facts and findings are the investigators'; the wording is ours. Nothing here is legal advice or a substitute for the report itself.