Anchor handling tug
Orcus is an anchor handling tug (AHT) owned and operated by Harms Bergung, a maritime services provider located in Hamburg, Germany. The tug was built at Mutzelfeldt Shipyard in Cuxhaven, Germany, on behalf of MAN Ferrostaal (now Ferrostaal) and was delivered in September 2010. Her commissioning works took place one month later in October.
In January 2011, the tug was contracted by Tullow Oil to tow a brand-new semi-submersible drilling rig, Ensco 8503, from the Gulf of Mexico to French Guyana.
In another contract, the tug and her sisters, AHT Taurus and AHT Pegasus, were engaged by Murphy Oil to deliver offshore support duties in Surinam.
Functions and specifications
The tug was designed by MAN Ferrostaal and Hitzler Werftfor for global offshore operations. Basic duties performed by the tug include long distance towing and anchor / hose handling. It performs berthing, fire fighting (FF) and salvage functions as well.
The overall length of the tug is 74.30m and length between perpendiculars is 66.65m. Maximum draught is 8m, while overall beam is 18.50m. Depth to main deck is 9.50m.
The tug can provide permanent accommodation for 59 persons. There are nine single berth cabins for officers and 19 double berth cabins are provided for crew members. Passengers can be accommodated in three four-berth cabins. A two-berth cabin is used as hospital.
Towing / anchor handling and salvage equipments
The maximum bollard pull capacity of the tug is 306t, while continuous bollard pull is 298t. The electricity driven towing winch has a capacity of 250t, pulling with a speed of 7.5m a minute (500t pull at 3.5m a minute).
The length of the main towing cable is 1,600m and diameter is 83mm. The two working cables, PS and SB, have a length of 2,000m and 800m respectively. There is also a 76mm spare towing cable of 1,600m length.
The tug is provided with two 3in cable lifters to lift and lower cables. For chain handling, there are two chain lockers, each with 93m3 capacities.
Salvage equipment includes two portable diesel-driven salvage pumps, a fast rescue boat and a work-boat with outboard engine capacity of 50BHP.
Deck equipments and tank capacities
The tug has a working deck area of 315m² (comprising two clear decks of 90m² and 225m²) and is equipped with two hydraulic cranes, each with a safe working load (SWL) of 4t at 12m outreach. There are two tugger winches of 10t each, pulling at the rate of 15m a minute.
A stern roller of 300t SWL is fitted at the stern edge of the tug. It prevents excessive damage to the stern by dragging various heavy objects aboard the ship.
Other equipment includes two pieces of Karmoy shark jaws (650/300t SWL), Karmoy fork / towing pins (650/300t SWL) and two high speed anchor winches.
Optional equipment includes an electro-hydraulic portable A-frame. It is operated with external power pack and has a SWL of 150t.
Tank capacity for heavy fuel oil (HFO) is 2,440m3, marine diesel oil is 190m3, fresh water is 130m3 and ballast water is 500m3. Luboil, sludge and fuel overflow tank capacity is 170m3.
AHT Orcus is powered by four MaK 9 MC 32 main engines, each rated 4,500kW. This power pack generates a maximum power of 18,000kW at 600rpm. The engines are connected to two twin gearboxes with a clutch.
Two controllable pitch propellers provide the propulsion. For steering, two flap type high performance rudders are mounted at the stern of the tug.
Manoeuvrability is achieved by three controllable pitch type side thrusters. Two of these are electric-driven bowthrusters (1,200kW each) and the third is a sternthruster of 400kW.
Electrical power supply is provided by two shaft generators, each of 2,000kW, and two MAK 3412DITA generator sets.
Navigational and communication equipments
AHT Orcus is equipped with Dynamic Positioning (DP) class-2 control system. The tug is provided with three remote controlled searchlights, three Gyro compass and A3 GMDSS equipment.