If a mooring line parts - where are you?

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If a mooring line PARTS - where are you?


By Senior Health and Safety Consultant, Master Mariner, Søren Bøge Pedersen

Imagine you are on a vessel preparing for the ship to moor. The sun is shining and the crew knows what do. The pilot is on board, the wind is perfect and the preparations are going smoothly. Everything is in control, so far. During the mooring, you hear a load crack and a scream immediately after. A workmate has been hit by a line that parted, snapped back and hit his upper chest.


The story ends here…

…but as any professional seafarer, we can see the nightmare begins. The sad thing is that it still happens much too often that our fellow seafarers around the world are hit by broken ropes while doing their job. The consequences
after being hit by a mooring line are enormous, both social and economic.
If you are lucky and not getting killed, you properly will suffer from long term
damages for the rest of your life. That is why we constantly need to alert each other of the risks using the
mooring lines. 



Marking does not do the job

Until recently, many mooring guides recommend the marking of snap back zones on the mooring deck around the critical points such as the warming drum, roller fairleads and pedestal rollers. The aim of these markings was to warn the seafarers to avoid standing in these zones when mooring lines are under tension.

So, the headline for this article could might as well have the name “Avoid snap back zones” but the truth is that seen from a mooring team point of view - it’s not possible.

You may say that seafarers engaged in mooring operations are somehow forced to be in the snap back zones in order to do their job – namely mooring the vessel. Due to the design and construction of mooring decks the mooring crew cannot avoid being in the snap back zones and the mooring deck

should therefore be considered as one big snap back zone.


Snap back zones are complex

Recent studies have shown that the nature of snap backs are much more unpredictable and complex than perceived before, due to nature of the mooring line used regarding elasticity and breaking strength, which may influence the path of a parted line.

Hence the marking of snap back zones on the deck, although convenient and simple, does not reflect the actual complex snap back zone and may lead the seafarer into a false sense of security that they are safe if they are not standing in the highlighted area. In principle, the whole mooring deck is a hazardous workplace and should be considered accordingly


What can you do as mooring team leader?


  • Invite the mooring team for an expanded risk assessment for mooring operations. It’s a good idea to prepare a Birdseye view of the mooring deck. A photo or a copy of the general arrangements could be used.


  • Identify the snap back zones together and explain how the zones are changing and developing as more lines are used and the zone increase.


  • It’s a good idea to divide the mooring operation into small bits as a process from the first line has been fastened to mooring has ended. Where can the crew be at the different stages? Where is it unsafe to be and where can you seek for cover?


  • Remember the snap back zones changes during the mooring operation and you must always have a constant focus on the mooring team.


  • Do not assume that the crew are situationally aware of the dangers as they are busy handling lines.


  • It’s is recommended to use the weather resistant SEAHEALTH poster as a training tool in the risk assessment process and as an alerting signage displayed at the mooring station. Posters can be ordered at www.seahealth.dk/shop


  • Before each mooring operation, carry out a pre-arrival meeting in order to refresh safety precautions and clarify roles and duties of each mooring team member.


  • Review the latest mooring and plan the next.


  • Do an instruction session. Give the new deck hand instructions to read about mooring. It would be best if you have something that exactly describes the mooring procedures on your ship.



What can you do as a rating engaged in mooring?


Have in mind that being in a snap back zone is just as risky as standing under a heavy net of goods. The mooring line may break as well as the wire for the hanging net.

Perceive the risk of being hit by a broken rope very seriously and minimise the stay in the snap back zone as good as you possibly can. Learn and understand the nature of the mooring ropes on your vessel with regards to elasticity and the breaking strength which influence the trajectory of a parted mooring line.


Never lose your awareness of where you are and treat every line under load with extreme caution and remember to stay clear of the potential path of a snap back.


Keep a close eye on your workmates and alert them immediately if any of them are in a snap back zone.


Be extra aware where you stand when handling the first line. Experience shows that the first lines ashore, such as spring lines, have the greatest potential of breaking as they are the only lines holding the ship.


When lines are subject to a straight pull, the snap back zone is minimal, but  if the lines are angled round a bollard or roller, then the snap back area increases.


Take ownership and responsibility of your own safety. Ask questions at pre-arrival meetings and in risk assessment processes.


Be aware of the risk of a line snapping back onto the deck if it parts outboard of the ship’s side, particularly if the deck is protected only by open railings.




The Nautical Institute has recently published a case study in its Mariners’ Alerting and Reporting Scheme (MARS) regarding an incident which occurred during mooring stations and is related to snap-back zones



The P&I Club SHIPOWNERS would like to bring attention the dangers of tensioned mooring lines and also highlight the concept of ‘snap-back’ zones



The diagram shows the potential areas of danger (snap-back zone) when the spring line parts at the spring line fairlead. The snap-back zone would be increased if both pedestal fairleads were used. (Swedish Accident Investigation Authority Report S-95/11 Morraborg)