Transport Malta’s Marine Safety Investigation Unit has issued an investigation report on an injury due to snapping rope, that took place at Teesport, UK, on 31 January 2023.
The incident
According to Transport Malta, on 31 January 2023, the vessel Tortugas was berthing at Teesport, UK. After securing one spring line and a breast line both forward and aft, the vessel received instructions to shift ahead by approximately 10 meters. For the shifting procedure, the officer supervising the forward mooring station positioned himself in close proximity to the forward spring line to monitor its adjustment.
However, it was discovered that the brake of the mooring winch for the forward spring line had not been loosened, and its gear had not been re-engaged.
During the attempt to shift ahead, the forward spring line, still under tension, unexpectedly parted, resulting in an injury to the officer.
The safety investigation determined that the forward spring line failed due to tensile overload. Following the incident, the Marine Safety Investigation Unit (MSIU) conducted an analysis and did not issue any specific recommendations based on the safety actions taken by the Company.
The complexity of mooring operations
Mooring operations constitute a critical task on board, essential for swiftly securing the vessel. Various factors contribute to the urgency, including financial aspects such as pilot and tugboat engagement. Moreover, the safety aspect is paramount, considering tidal streams, currents, and winds, particularly in tidal ports. Prolonged mooring operations expose the vessel to natural phenomena, placing considerable strain on already fastened mooring ropes. Delays in mooring operations further hinder the vessel’s timely positioning for effective cargo operations, leading to potential financial repercussions.
While mooring is routine for all deck crew members, it remains a hazardous and complex task. The mooring deck layout, with its equipment and fittings, poses obstacles for crew members working under time pressure. Hazards also arise from mooring equipment or fitting failures, resulting from wear and tear or material fatigue. Among the common causes of injuries during mooring operations is the failure of a mooring rope. The unpredictable path of parted rope sections, especially under tension, makes the entire mooring deck a hazardous area, constantly exposing crew members to risks.
Completing a mooring operation quickly demands swift actions from crew members who must juggle numerous simultaneous tasks. Their actions depend on their understanding of the situation at any given time. This context emphasizes the complexity of a mooring station, where accidents can potentially lead to severe consequences.
The additional task of communication with the bridge further complicates matters for crew members at the mooring station. Instructions from the bridge or requests for vital information compete with other pressing tasks for the crew members’ attention. When crew members find themselves in unsafe positions on mooring stations, it may be a conscious decision, assuming that the ropes and other mooring equipment will not fail. Alternatively, crew members may unknowingly place themselves in unsafe positions, particularly when focused on executing instructions or addressing queries from the bridge. Clear visibility of the mooring deck and effective communication are crucial. If one crew member observes another in an unsafe position, they can advise them to move away from that location.
Conclusions
The forward spring line parted due to tensile overload. The rope’s residual breaking load had most probably been lowered by previously broken fibers and yarns, making the rope susceptible to overload caused by dynamic loading conditions.
Past high load events may have caused creep damage, significantly lowering the rope’s maximum breaking stress prior to tensile failure. Although the crew members knew that the forward spring line had to be slackened for the vessel to move ahead, neither the third officer nor any of the other crew members had gone to the mooring winch to loosen the brake and engage the gear. This was indicative of a communication gap between the members of the forward mooring team.
The seriously injured third officer had positioned himself in close proximity to the forward spring line and did not use the pedestal specifically fitted to observe the mooring ropes since he felt that using it involved a risk of falling overboard.
The condition of all mooring ropes was noted as satisfactory by the chief officer in December 2022, while after the occurrence, the PSCO observed that three additional mooring ropes of the forward station needed to be replaced. This suggested that a visual inspection of mooring ropes by crew members may tend to be subjective.
Lessons learned
Following its internal investigation of this occurrence, the Company took the following actions across its fleet:
- Reviewed and updated the section on mooring operations in its safety management manual (SSMM).
- Implemented an electronic line management plan (LMP), which included guidance on the required documentation and wear and tear identification.
- Circulated the lessons learnt.
- Introduced an awareness campaign on the human element of safe mooring, addressing training (including e-learning and computer-based training modules), SSMM requirements, and vessel-specific risk assessment.
- Ensured that its vessels completed a thorough inspection of all mooring lines and documented details of the inspection either in the PMS or LMP.
- Verified the fleet’s status of replacement of old mooring ropes with snap-back arrestor-type mooring ropes, and several mooring ropes have been replaced across the fleet.
- Ensured that its vessels had set up tasks for mooring winches, their brakes, mooring lines, and other associated tasks/inspections in the PMS.
