The Boa Sub C and Boa Deep C are two offshore support vessels designed to support Chevron’s deepwater offshore developments in the Gulf of Mexico. The Boa Sub C is being used for the offshore installation activities of Chevron’s Blind Faith platform.
Boa Sub C
The Boa Sub C has an overall length of 120m, a moulded breadth of 27m and a draught of 8.8m. The depth to the first deck is 11.6m. It’s gross tonnage is 12,400t and it’s deadweight is 9,000t. The vessel has a helideck designed for a Super Puma/S61 helicopter.
The ship has 105 single cabins, with ten equipped with Pullman beds. The vessel’s facilities include a cinema, gymnasium and sauna.
The Boa Sub C has a fuel oil capacity of around 2,800m³ and can carry 3,700m³ water ballast/drill water. It can also carry 1,300m³ of fresh water.
In addition, the vessel can carry tanks of lube oil (200m³), hydraulic oil (65m³) oily water (45m³), sewage (140m³), grey water (140m³), sludge ( 87m³) waste oil (75m³), drain ( 27mf³) and bilge (30m³).
The vessel is equipped with a 400t AHC mid-ship crane and a 30t AHC stern crane, capable of working at a depth of 3,000m. The mid-ship crane, supplied by National Oilwell Varco, has a hoisting speed of 35m/min at 200t and its working radius is 42m.
For data and telephone communication, the vessel has been equipped with Dual VSAT C-band system. The vessel also supports an ethernet data communication network.
Boa Deep C
The Boa Deep C has two work-class remotely operated underwater vehicle (ROV) hangars on its port and starboard. It uses two Oceaneering Millenium-designed ROVs rated at 3,000m water depth. The ROVs can be deployed in a typical wave height of 4.5m.
The vessel is installed with a 250t AHC mid-ship crane and 30t AHC stern crane, capable of operating up to a depth of 2,000m.
The ship has 1,150m² of free deck space. In order to carry out installation work, the deck is reinforced for a specific load of 15t per square metre.
Power is provided by two 2,420kW generator sets, two 1,820kW sets and a 910kW genset. There is also a pair of 4,800kW shaft generators, giving a total capacity of 18,992kW.
The vessel’s main propulsion is based on two 9,000kW engines and a 1,200kW azimuthing propeller, giving a total output of 19,200kW. In order to manoeuvre, there is a pair of fore and aft 1,425kW tunnel thrusters.
The Boa Deep C’s total thrust capacity is 6,900kW, allowing a bollard pull of over 260t, a maximum speed of 15kt and an economy speed of 12.5kt. The vessel is equipped with anti-heel and roll damping tanks.
The ship has an active heave compensated crane with a 250t lifting capacity at 15m and a working depth of 2,000m. A 500t anchor handling drum (with an inner diameter of 3,500mm and a 5,700mm external diameter) has a capacity for 8,100m of 90mm diameter wire.
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