Navy divers salvage sunk Tug de Mist
THE SA Navy has succeeded in getting the vessel Tug de Mist out of the water after days and nights of ingenuity, tenacity and sheer hard work.
Tug de Mist sank on Saturday, November 10, in the still water basin of Simon’s Town Harbour, settling on her port side at a relatively shallow depth of 10m.
After a comprehensive assessment was conducted by the Naval Engineering department and Navy divers, operations commenced to bring her out of the water using a limited array of lifting bags and submersible pumps.
Commander Greyling van den Berg said: “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.”
The salvage entailed raising the tug off the seabed and towing her to the Synchrolift facility about 50m away.
However, shallow water salvages are known to be extremely difficult (because of the lack of air expansion and buoyancy at this depth).
The main challenge over the past few weeks was trying to make the 39-year-old tug airtight (and thus buoyant).
The divers used underwater welding equipment to seal off holes to pump her full of air, but as soon as the leaks were sealed, other leaks were discovered.
However, the personnel of the Armscor Dockyard were constantly on hand to provide bungs and other mechanisms for leak stopping and shoring.
On Wednesday, the Navy divers concentrated all lifting efforts to the aft of the tug, and managed to raise her and bring her 2m away from the quay, with her keel resting on the bedrock.
The same was achieved on the forward side.
The Mooring Lighter (built by dockyard apprentices more than 100 years ago) was used as a mechanism to create further lift.
On Monday, Naval riggers, in conjunction with the Naval Harbour Master, devised a way to use “snatch blocks” to create further buoyancy.
Through continued effort, by Wednesday the tug was floating, but still listing slightly, and she was finally pulled to the Synchrolift.
“This exercise also provided invaluable practical salvage experience for the Navy divers, at no cost to the organisation.
“A floating barrier was also put in place to contain the oil spill within the still water basin, with a second barrier between the still water basin and outer basin,” Van den Berg said.