APRIL 8, 2013 — Two 67 m, 80 ton bollard pull AHTS vessels built for Topaz Energy and Marine, a subsidiary of Oman-based Renaissance Services SAOG, the Topaz Dignity and Topaz Triumph, have MAN Diesel & Turbo medium-speed propulsion packages.

Topaz Dignity on the slipway

Built by Abu Dhabi-based shipbuilder Adyard, the 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 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-m intermediate shafting, and 13 m 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, customized 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.

After sea trials for the Topaz Triumph, Stewart Smith, Topaz Marine's Project Manager,  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.