Cable-laying ship on way to finish Tasman Global Access cable
The ship that is laying an undersea cable between Australia and New Zealand has docked briefly in Auckland en route to the next leg of its journey.
Part of the Tasman Global Access (TGA) undersea cable has been built from Australia and laid 1400 kilometres out from Australia's Narrabeen Beach into the Tasman Sea.
French ship Ile de Re is on its way to the middle of the Tasman Sea where it will pick up the cable and continue laying the final section, which will end at Ngarunui Beach in Raglan.
Upon completion, the cable is expected to improve New Zealand's international broadband connection.
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Spark, Vodafone and Telstra invested $100 million to build the cable which will be the first international cable laid from New Zealand since work started on the Southern Cross Cable linking New Zealand, Australia and the United States in 1998.
Spark wholesale general manager Lindsay Cowley said the physical build was expected to finish in December this year and the cable should be in use in late January.
However, there would not be a significantly noticeable difference in internet connectivity, at least not in the beginning.
"The project is around ensuring we have a good reliable supply, so we've got different cable routes to key markets Australia and Asia," Cowley said.
"It's ensuring if there is an event that led to one of the cables connecting to New Zealand not working, then we've got another cable that will continue to carry traffic."
Cowley said the cable will carry 500 gigabits of internet traffic once it is launched, with a total capacity of 20 terabits.
HOW IT WORKS
The 140 metre long Ile de Re is carrying about 1500 tonnes, or 500,000km, of cable on board.
Made in France, the cable is only about 17 millimetres thick. More insulation is used around the parts of the cable built in shallower water, but even then it will be no bigger than 40mm.
The cable is spooled out of two tanks on the ship, which carry 500km of cable each.
It takes about a dozen staff to hand-coil the cable inside the tanks.
There has not yet been an automated way invented for coiling the cable and it is crucial this is done right, otherwise either or both the cable and the ship could get damaged.
The cable is laid up to a depth of 5000 metres into the sea.
Where the water is less than 1500 metres deep, the cable is buried into the seabed using a cable plough.
Located on the back of the ship, the plough feeds the cable out to sea and is buried 1 metre below the seabed.
There is also a remotely operated vehicle available on the ship, complete with robot arms and cameras.
It can float on the water and perform maintenance on the cable.
The crew on Ile de Re work 12 hour shifts and the ship is out at sea for four to five weeks at a time.