Since the upsurge in ordering of drillships, Rolls Royce has been successful in capturing nearly 90 per cent of contracts for thrusters for these high-specification vessels, which will use dynamic positioning to keep position while drilling in ultra deep waters. An example is the Stena Forth.
Many of the owners of this new generation of drillships have chosen Rolls-Royce again to meet their propulsion requirements because they have found the UUC series azimuth thrusters on their existing vessels to be efficient and reliable.
The favoured thruster type is the UUC range in various sizes as these are designed to be mounted and dismounted underwater without needing to drydock the vessel. This of course saves much time & expense when repairs are needed.
Samsung Heavy Industries is building many of these vessels. For example, the three vessel Stena Drill Max series for Stena Drilling all have six of the UUC 455 azimuth thrusters, each rated at 5,500kW. They work in conjunction with the vessel’s Class 3 dynamic positioning system. The recently launched first vessel, Stena Drill max, is to work in the Gulf of Mexico initially, but is also suited to harsh environments such as the Norwegian and Barents Seas. It can operate in up to 3,000 metres water depth.
Seadrill is building three drillships of a Samsung design with double derrick drill package. Rolls Royce is providing the thruster outfit; six azimuth units each accepting 4,500 kW and either operating in the DP 3 dynamic positioning system or giving a transit speed of 11.5 knots. The first of these drill ships, West Capella, is due to start operations in the first quarter of 2009.
Rolls Royce thrusters are also on order for other vessels at Samsung, including drillships for Pride International, Cardiff Marine, Saipem and Tanker Pacific Management.
Transocean has ordered four drill ships for operation in ultra deep waters from Daewoo (DSME) in Korea. Due to start operations in 2009, Discoverer Clear Leader and its companions are enhanced versions of Transocean’s Enterprise drill ships. The first three are scheduled for operation in the Gulf of Mexico and the fourth offshore Angola. All will have Rolls Royce azimuth thrusters; six units each with a total power of 6 x 5,500kW. A UUC thruster equipped drill ship is also on order at DSME for Taiwan Maritime Transport.
Also in Korea, Hyundai is building a drill ship for Global Sante Fe using Rolls Royce thrusters for propulsion and dynamic positioning. This will be an upgraded version of the existing C R Luigs and Jack Ryan vessels.
Apart from equipping drill ships, the UUC range of thrusters are in demand for propelling and positioning many of the semi submersible drilling rigs that are under construction, in some cases together with Rolls Royce mooring systems and Bergen engines.
Rolls Royce is one of the world’s leading manufacturers of azimuth thrusters. The propeller rotates 360 degrees around the vertical axis so that the thruster can perform both the propulsion and steering duties for a vessel, or positioning for a semi-submersible rig, drillship or FPSO.
Ultra deep water is generally considered to be depths of over 800m.