Operational regions include West Africa, Brazil, Gulf of Mexico and the North Sea.
YANTAI – The semisubmersible OOS Gretha was launched on November 25, 2013 with six Thrustmaster 5000 HP (3700 kW) Azimuth DP3 Thrusters classed by ABS.
The Brazil bound semisubmersible drilling rig was built at the Yanti CIMC Raffles shipyard and is due to work for Petrobras offshore drilling.
CIMC Raffles said it is the first asymmetric semisubmersible unit without bracing in the world. This reduces the towing resistance and dynamic positioning load, improving self propelled transit speed from an average 8 knots to more than 12 knots.
The asymmetric pontoon outline, with pneumatic de-ballast system, also aids quick ballast adjustment, to suit heavy lifting operation.
The OOS Gretha is 137.5m-long, 81m-wide, 39m deep (base line to main deck), with a maximum variable load of 7070-ton. It can accommodate 618 people.
The vessel has two 1800-ton offshore mast cranes, which can perform tandem lifting, and it can withstand more than 22m wave height, says CIMC. Its specification means it can work in West Africa, Brazil, Gulf of Mexico and the North Sea, added CIMC.
