Mooring operations are among the most dangerous tasks carried out on board ships. Data collected by the Australian Maritime Safety Authority (AMSA) indicates that mooring incidents occur regularly and often result in injury. Furthermore, in the last 10 years, two fatalities have occurred during mooring operations in Australian waters.
While there have been various innovations across the maritime industry to reduce the hazards associated with traditional mooring systems, the majority of vessels still rely on mooring arrangements involving ropes and winches. These systems have benefits, as they are flexible and enable berthing at most ports. However, the risks associated with operating traditional mooring systems continue to increase as vessels become larger.
Failure of mooring line on board LNG carrier Zarga with 1 person injured
A deck officer suffered severe head injuries when he was struck by a parted HMPE mooring rope during a berthing operation at South Hook LNG terminal, Milford Haven on 2 March 2015.
The area where the officer was standing was clearly within the snap back zone of the rope but had previously been designated as a safe area.
The perception on board was that HMPE ropes did not recoil on failure, and the elasticity introduced by the rope’s tail had not been properly assessed.
The vessel’s mooring lines were not fit for purpose, they did not have the minimum breaking strength specified at build. they were not compatible with the vessels mooring deck fittings and the required working load limit was too high.
The predominant failure mode, axial compression fatigue, had not previously been associated with HMPE rope failures.
The rope’s tightly bound jacketed construction increased the likelihood of axial compression fatigue and prevented the crew from inspecting its load bearing core and identifying key discard criteria.
Guidance provided by the rope manufacturers and shipping industry bodies for the selection and use of high modulus synthetic fibre mooring lines was limited and often contradictory.
(Marine Accident Investigation Branch 2017)