In a few months, the giant Aasta Hansteen spar platform will afloat in the ocean, anchored to the seabed around 300 km offshore, northwest of Sandnessjøen in Nordland. But how it will get there is the story of a voyage with a difference. Norway’s first spar platform, and the world’s largest, had to travel around the coast of Africa to reach her destination.
Taking on this unusual challenge was the world's largest heavy transport vessel, Dockwise Vanguard. 275 metres long and 79 metres wide, the ship is the length of three football pitches, and more than a football pitch in width. When it submerges to lift large installations, the semi-submersible looks more like a block of flats jutting out of the sea than a ship. It is designed to lift and carry loads equivalent to 12 Eiffel Towers at a time.
In April, Aasta Hansteen’s gigantic substructure was ready for the long voyage from the shipyard in South Korea. Planning, accurate assessments and calculations were necessary to get the spar platform out into the water and om board the Dockwise Vanguard, ready for departure.
Aasta Hansteen’s floating spar base alone weighs 46,000 tonnes and is 200 metres tall, with a diameter of 50 metres. By comparison, Oslo Plaza Hotel is 117 metres tall, 83 metres shorter than Aasta’s jacket.
For two months, the platform hull crossed several oceans on its journey to Norway. From South Korea, the voyage went south to India, and continued south around the Cape of Africa. At that point it was barely halfway to its first stop: Høylandsbygd in the county of Sunnhordland. The ultimate destination is the Norwegian Sea at the northern edge of Europe. The trip was 14,500 nautical miles, equivalent to nearly 26,900 km, or more than 640 marathons—a distance that amounts to more than half of the Earth’s circumference.
Here, the hull was floated off the transport vessel and towed into Klosterfjord in the country of Hordaland, where it was upended in the sea before being anchored inposition to await the arrival of the topsides. The platform deck followed, making the trip aboard the Dockwise White Marlin this autumn and arriving at the end of November. Soon the platform deck will be transferred to two other vessels in order to be floated over and connected to the hull at Stord.
Tension before the transfer
Skidding out an entire platform deck of this size onboard a ship requires great skill, and there were many anxious faces to be seen at the yard as the operation took place. It has been an unusually large project for the yard and Statoil.
When everything has been joined together and the platform is in place in the Norwegian Sea, production will start in 2018.