Brazilian state oil company Petrobras has awarded Brazil Offshore Services (BOS) long term charters
to operate one vessel under the Petrobras 12 000 contract and another under the Petrobras 15 000 contract. BOS is a Brazilian joint venture company owned 50/50 by Farstad of Ålesund in Norway and Petroserve of Brazil.
BOS in turn has selected Rolls-Royce design and equipment packages worth altogether about NOK 270 million for the two vessels. Both will be to the UT 722L design, but specifications vary to suit the two operating contracts, each of which has an eight year period. Estaleiro Itajai in Brazil has been chosen as the builder of these vessels, which will be of a very high standard. Deliveries are scheduled for 2005.
The UT722L is a multi-function anchor handling tug supply vessel, and is a lengthened version of the UT722. Farstad ordered the first example of each design; the UT 722 Far Grip which entered service in 1993 and the UT722L Far Senior in 1998, and currently has three UT 722 and two UT 722L AHTS in its fleet.
Ship Technology – Ulstein in Rolls-Royce is responsible for the designs and associated comprehensive equipment packages. The main role for the vessels will be setting out anchors and laying and maintaining moorings for floating oil installations in the Brazilian deep water offshore fields. They will therefore have powerful and complex Rauma Brattvaag low pressure hydraulic winch outfits for handling chain, wire and synthetic fibre rope. Supply capacity will be secondary to towing and anchor handling, but the two vessels are to be equipped to FiFi II standard for firefighting and will also have equipment and a substantial tankage for oil recovery.
The main difference in specification is in the engine power and machinery layout. The vessel for the Petrobras 12 000 contract will have a bollard pull of over 150 tonnes, and will have a twin engine installation – two Bergen 12 cylinder BVM-series units. The other is to have a more powerful four engine father-and-son layout, using an eight cylinder Bergen B32:40 longstroke engine and a six cylinder unit of the same type driving each of the two Kamewa Ulstein CP propellers. In this case the bollard pull will be in excess of 180 tonnes.
Dynamic positioning to IMO DP1 has been specified, and to achieve this the CP propellers and high lift rudders will be assisted by two Kamewa Ulstein tunnel thrusters at the stern, each rated at 736kW, an 883kW tunnel bow thruster and a 1,120kW Ulstein Aquamaster swing-up azimuth thruster under the bow.
There is to be accommodation for a total of 30 people, and in accordance with its usual practice, Farstad has stipulated very low levels of noise and vibration.
Similar winch systems have been chosen for each vessel. The main anchorhandling winch will be a two drum unit, rated at 350 tonnes pull on the first layer, which is less than some of the other AHTS in the fleet, but balanced by a higher hauling speed. Chain lifters for up to 165mm chain will be provided and there will be very large rig chain lockers totalling 560m3. Four secondary winches will be stacked in pairs above and ahead of the main winch, each with a 125T pull and 170T brake rating, intended for fibre rope.
When the two vessels enter service Farstad and BOS will have altogether 12 offshore support vessels operating for Petrobras in Brazilian waters.
Farstad has chosen UT-Designs since 1987 and to date has put into service examples of the UT 705, UT 712, UT 722, UT 722L, UT728, UT 730, UT 745, UT750, UT 755 and UT 755L designs, in some cases several of each or the first of the type. At present the company has a UT728L under construction at Itajai for its Brazilian BOS joint venture, a second UT712 due for delivery in July 2003 from Simek in Norway for the IOS joint venture, following Lady Caroline which was handed over in March of this year, and a UT 755 at Brevik also for IOS.