After several days of strenuous efforts, the South African Navy successfully salvaged the Tug de Mist out of the Still Water Basin of Simon’s Town Harbour on December 5 2018.
The Tug de Mist sank on November 10 settling on her port side in a shallow depth of 10 metres, prompting the Naval Energy department and Navy divers to bring the boat out of the water using a limited number of lifting bags and submersible pumps.
In order to save the tug, it had to be lifted off the seabed and towed into the Synchrolift facility, a dock where boats are repaired or lifted out of the water. The facility was an estimated 50 metres away and shallow water salvages are known to be difficult due to the lack of air expansion and buoy available at that depth.
Tug de Mist is 39-years-old and the main challenge in salvaging the boat was attempting to make it more airtight and buoyant.
The SA Navy explained how divers attempted to prevent more leaks during the retrieval.
“The divers used underwater welding equipment to seal off holes in order to pump her full of air, but as soon as leaks were sealed, other leaks bubbled to the surface,” said an official statement
On November 28, Navy divers were able to raise the tug 2-metres away from the quay. The Moor Lighter, built by dock apprentices over 100 years ago was used as a mechanism to further lift the tug out of the water. Unfortunately, the Moor Lighter does not have a generator and cannot operate a capstan, a mechanism used to allow the boat to reel in other structures.
“In order to mitigate this, the winch of Tug Umalusi was used to create this lift through the Mooring Lighter’s fair leads. The docking plate under the tug kept on getting stuck in the sand during the lifting process, adding to complications,” said the SA Navy.
During the lifting process, divers continued to repair leaks, filling fuel, freshwater and ballast tanks with air.
Naval Harbour Master and Naval riggers created a way of using ‘snatch blocks’ to increase buoyancy to raise the tug high enough to clear the platform of the Synchrolift.
On December 5 2018 at 3pm, the tug was finally lifted out of the water and pulled into the Synchrolift.
SA Navy, Commander Greyling van den Berg, acknowledges the achievements of those involved in saving the tug.
“The salvage operation and obstacles overcome is an amazing display of teamwork and resourcefulness by the dedicated team of professionals who worked tirelessly to solve numerous mathematical, physical and engineering problems,” he said.
Picture: SA Navy/Tug de Mist