Navy divers sal­vage sunk Tug de Mist

Cape Times - - PAGE 2 - STAFF WRITER

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.

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