Mooring near-miss: Lines break during un-docking operation

  • Safety Flash
  • Published on 18 April 2016
  • Generated on 23 July 2026
  • IMCA SF 10/16
  • 1 minute read

The Danish safety organisation Seahealth.dk has circulated a near miss incident in which lines parted during undocking operations.

What happened?

A vessel’s mooring lines (double braided synthetic fibre rope 65mm) were used as tug lines (two lines connected to one tug). When the vessel dropped off all the lines from the berth, the tug started pulling the vessel. After about three minutes the two lines parted. There were no crew standing in the area where the tug line was connected. There were no injuries and no damage to the vessel except for the two failed mooring lines.

It will be understood that the potential consequence of this incident could have been a fatality.

Investigation revealed that the mooring ropes bore no sign of damage prior to the incident, and had been in operation since delivery of the vessel in 2005. The same vessel had seven other mooring lines in use of that age.

Members may wish to refer to the following:

Latest Safety Flashes:

MAIB: Catastrophic engine failure and subsequent fire

MAIB has published Accident Investigation Report 10/2026 into a catastrophic failure of a diesel generator engine on board the vessel Kommandor Susan.

Read more
BSEE: Compressed gas cylinder hazards

BSEE has published Safety Alert 516, relating to potential risks involving compressed gas cylinders.

Read more
MSF: dropped object inside vessel tank

MSF have published Safety Alert 26-05 relating to a tank cleaning machine coming lose and falling within a tank on a vessel.

Read more
Uncontrolled movement of cargo

During offshore cargo operations alongside a rig, a single pipe loaded on deck shifted due to vessel motion and swell conditions.

Read more
Positives – rubber seals on hatches, securing of shackle pins, fuel sample box

A Member reports a few positive findings.

Read more

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of the entire offshore industry.

The effectiveness of the IMCA Safety Flash system depends on the industry sharing information and so avoiding repeat incidents. Incidents are classified according to IOGP's Life Saving Rules.

All information is anonymised or sanitised, as appropriate, and warnings for graphic content included where possible.

IMCA makes every effort to ensure both the accuracy and reliability of the information shared, but is not be liable for any guidance and/or recommendation and/or statement herein contained.

The information contained in this document does not fulfil or replace any individual's or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.

Share your safety incidents with IMCA online. Sign-up to receive Safety Flashes straight to your email.