A UK marine aggregate dredger was undergoing mooring operations alongside a wharf on the river Thames. The vessel’s bow thruster was inoperative and a tug was assisting, secured at the port shoulder.
The forward backspring was being used to arrest forward movement and bring the stern of the vessel alongside and was cut when it was forced against the corner of a metal fender by the vessels hull. The line parted outboard of the bulwark, so the majority of the energy was dissipated aft and upwards and the line carried significantly reduced energy when it struck the forecastle. CCTV footage of the incident shows sufficient energy in the line to have caused significant harm to anyone it struck.
Although the crew had been briefed on the hazards of the manoeuvre and were aware of the danger areas when the brake was applied to the spring line, CCTV footage shows both crew on the forecastle positioning themselves directly in the snapback zone of the line and not paying attention to the line as the weight comes on. Fortunately, no injuries or damages (other than to the mooring line) resulted.
- A pre-arrival briefing was conducted with the mooring parties but it was not comprehensive as the berth is visited regularly and the vessel had been operating without the bow thruster for about a week.
- The berthing manoeuvre and sequence of running lines was discussed.
- The forecastle crew had held a toolbox talk which focussed on the role of the tug. While they were very aware of the snap-back hazard posed by the backspring, the CCTV footage shows both positioning themselves within the snap-back zone whilst preparing to run the headline.