MAN Diesel & Turbo’s medium-speed propulsion packages have gained another foothold in Middle Eastern offshore operations. After successfully completed seatrials, Abu Dhabi-based Adyard has earlier delivered the ‘Topaz Dignity’ – which is now followed by the ‘Topaz Triumph’ AHTS.
Topaz Energy and Marine, a subsidiary of Oman-based Renaissance Services SAOG and a regional leader in providing offshore support vessels and engineering services, has passed yet another milestone in its 35-year history by building two Anchor Handling Tug Supply vessels.
The two 67-metre, ’80-ton bollard pull’ vessels are ready for anchor handling tug supply services and the transportation of dry and liquid cargo to and from pipe-laying barges, drilling platforms and production platforms for offshore operations. The Topaz Dignity will operate on behalf of BP, the oil and gas major, on a long-term-contract basis in the Caspian Sea – whilst Topaz Triumph may remain in the Middle East and be operated by Topaz Marine MENA. The state-of-the-art vessels are equipped with the latest technical equipment and are custom-built for Fi-Fi Class I and DP2 operations.
Propulsion package
The twin-screw propulsion package for each vessel consists of 8-cylinder, medium-speed MAN L27/38 engines of 2,720 kW each, horizontal offset reduction gearboxes with an CPP servo oil distribution unit, and a 1,500 kW shaft alternator PTO. The gearboxes drive approximately 18-metre intermediate shafting, and 13 metre propeller tailshafts in oil-lubricated stern tubes. The MAN Alpha CP Propellers are 2,800 mm diameter ducted, turning 198 r/min at MCR. The propeller thrust and pulling power is boosted by Alpha High Thrust nozzles, customised to hull integration with a length/diameter ratio (L/D) of 0.6. The Alphatronic 2000 Propulsion Control System is configured with twin control stations on both main bridge, aft bridge and in the engine control room – including interfaces to joystick and dynamic positioning systems.
Performance
Upon completing seatrials for the Topaz Triumph – Topaz Marine, Project Manager, Stewart Smith, expressed his satisfaction with the propulsion system and vessel performance in general: “Everything fulfilled our expectations. Compared to the estimated design speed of 13.5 knots for the vessel, we even achieved a radical increased top speed of 15 knots”. Additionally, a bollard pull test verified the vessels’ pulling power specification by achieving a test result of 87 tons.