VIDEO: Shell Prelude now under tow to Australia

JUNE 29, 2017 — The world's largest floating LNG facility (FLNG), Shell's Prelude, is now under tow from shipbuilder Samsung Heavy Industries shipyard in Geoje, South Korea, to gas fields off the coast of Western Australia. It is a journey of some 5,800 km (3,600 miles).

Prelude is 74 m wide and 488m long. It is being towed by three POSH Terasea tugs, each more than 75m long. A fourth tug acts as an escort.

Prelude now faces a journey of at least a month to its new home off the coast of Australia. The most difficult part was at the beginning, when nine additional tugs carefully coaxed Prelude from the harbour through a narrow U-shaped channel into open waters.

"The channel has strong currents and Prelude is very large, so you can imagine it's like a fast car turning a tight corner. The manoeuvres had to be very precise," says Captain Gerald Seow, Chief Executive of PACC Offshore Services Holdings, the Singapore-based marine services company in charge of the ocean tow (POSH Terasea is a joint venture between PACC Offshore Services Holdings and Terasea Pte Ltd.

Willem Keij, a Shell engineer responsible for the tow, experienced mixed feelings as Prelude departed. "I'm excited, of course. But I also feel a tremendous sense of responsibility," he says. "All the years of planning have finally led to this moment: we are the team taking Prelude safely to Australia."

Keij is one of 160 people staying on board Prelude during the journey. He describes his role as "the spider in the web," gathering information from each of the tugs and from Stockwell, helping decide which route to take depending on the weather, and communicating with the Shell project team in Perth, Australia.

At top speed, Prelude will be traveling at around five knots, about the same pace as a fast walk. Along the way, the convoy may encounter small fishing boats and other vessels that Prelude will need to safely avoid.

The convoy left Geoje at the end of June and moved into the East China Sea, across the Korea Straits. It will then go through the Philippine Sea, past the islands of Indonesia and across the Timor Sea. At the Indonesian archipelago, a fifth vessel will meet the convoy to help refuel, replenish supplies and replace the crew.

Once Prelude reaches its final destination, work will start to plug it into the undersea infrastructure. As 16 pre-laid mooring chains are lifted from the seabed and attached to Prelude's 93-m high turret, a sixth towing vessel will join the five boats to keep the facility in place.

Because Prelude sits in an area of cyclones and strong ocean movements, the turret will allow the facility to pivot safely with the prevailing current and wind. Once operational, this ability to act like a weathervane means Prelude can ride out storms without having to disconnect the flexible pipelines that feed in gas from deep below the waves.

When all 16 chains are in place, Prelude will be considered storm-safe and the work of the tugboats will be officially complete

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