Two marine tugboats that were sunk at the dock after a ship crashed into them have been recovered from the bottom of the Mersey River in Tasmania.
AAL Shipping has undertaken a salvage operation to remove the two tugs from the river in Devonport on the north-west coast of Tasmania that had been sunk by a cement carrier in January.
New South Wales based emergency response, salvage and environmental support specialist, United Salvage, engaged AAL to supply a vessel from its longstanding Asia to Australia East Coast Liner Service. The AAL Melbourne a 31,000DWT 700 tonne heavy lift vessel was chosen for the job, and was able to not only salvage the tugs, but also transported them to Brisbane.
“United Salvage originally planned to use a floating crane and barge to recover these tugs,” said Chris Yabsley, chartering manager at AAL Australia.
“However, once we demonstrated that our A-Class vessel could not only recover the tugs but also transport them back up the East Coast for delivery to Brisbane, it was clear that AAL would be the perfect partner.”
The first tug, the 420 tonne York Cove, was pulled out of the Mersey on August 7th using the AAL Melbourne’s two port-mounted cranes working in tandem. The tug had to have large holes cut into its hull to allow trapped water and sediment to drain.
The second tug, the 455 tonne Campbell Cove, was recovered and loaded onto the AAL Melbourne a few days later. Both tugs were lashed to the weather deck of the ‘mega size’ vessel in preparation for their onward shipment to Brisbane, using specifically designed cradles.
The recovery was carefully planned and modelled over several months and involved collaboration with several key stakeholders including United Salvage, TasPorts and cargo insurers. The Australia Maritime Safety Authority (AMSA) was required to confirm calculations.
“Lifting took time as the tugs weighed significantly more than expected, due to trapped water and fuel. Working throughout the evening on the second tug, the full weight of the tug stayed on our ship’s cranes overnight – awaiting the salvage company to pump out whatever was still trapped inside her,” said Nicola Pacifico, head of transport engineering at AAL.
Yabsley added, “As the proposed position of our vessel during the salvage operation impacted the swing basin for critical port operations needed to keep Tasmanian supply chains open, we worked closely with the Harbour Master and Pilots to avoid impacting other port movements. The removal of the sunken tugs allows Devonport to return to normal operations.”
TasPorts CEO Anthony Donald estimated that more than 100 people worked on the project. “We not only had the significant challenge of tide and weather, but also the natural eddies in the area and potential marine pollution,” he said. “TasPorts worked closely with EPA Tasmania, which had representatives on site to advise on environmental management. The insurers and salvors, that have extensive international experience, say it was one of the most complex salvage activities they have ever undertaken. The salvage itself was slow and deliberate and reflects the detailed and collaborative planning that was required to complete the operation successfully.”