STENA SIRITA 127,466-dwt Crude Oil Tanker
STENA SIRITA, a 127, 466-dwt offshore loading twin-screw shuttle tanker was delivered in August 1999 to Stena Ugland Shuttle Tanker Ltd.by Hashihama Shipbuilding Co., Ltd. /Tsuneishi Shipbuilding Co., Ltd. The vessel that twin-skeg type shuttle tanker was designed for the first time in Japan for offshore loading of crude oil via a bow loading system at the North Sea oil field and for shuttle transportation.
During offshore loading, the vessel is able to keep its position by dynamic positioning system (DYNPOS AUTR and Equipment Class II) emphasizing safety aspects through redundancy, which consists of two (2) controllable pitch propellers driven by two (2) main engines, two (2) special rudders with flap, two (2) bow thrusters and control and position reference systems. Furthermore, two (2)stern thrusters, one (1) on each skeg, are arranged and used as a back up in the event of failure of one of two aft lateral thrust systems.
Hull structures are strengthened compared with the conventional tanker in consideration of the severe sea weather. For durable and long term ship operation, structural analyses were conducted through simulation of the maximum and repetitive loads on the vessel. Special coating with long lasting performance against corrosion is applied to inside surface of ballast tanks and cargo oil tanks. (CSA-2 (25))
Total enclosed bridge is arranged to improve the work efficiency of the crew, which is extended from the wheelhouse to both sides of the bridge. The cockpit type arrangement is adopted in the bridge for centralized control system including bow loading and vessel's position keeping.
Furthermore, the submerged turret loading (STL) system is able to apply in the future since the vessel is already provided with a cone (opening) at the bow bottom to connect with an oil loading buoy under the sea surface.
If the need for the STL system arises, the STL system can be completely installed on the vessel without drydocking.
PRINCIPAL PARTICULARS
Length (o.a.) ... 262.613 m
Length (b.p.) ... 247.000 m
Breadth (mld.) ... 46.000 m
Depth (mld.) ... 23.700 m
Draft (mld.) ... 15.700 m
Gross tonnage ... 76,836
Deadweight ... 127,466 MT
Main engine ... MAN-B&W 7S50MC x 2 sets
MCR ... 13,100 PS (9,635 kW) x 123 rpm
NOR ... 11,140 PS (8,193 kW) x 117 rpm
Speed (max. trial) ... 16.44 knots
(service) ... 14.6 knots
Complement ... 30
Classification ... DNV
Cargo pump ... 4,000 m3/h x 135 m T.H. x 3 sets
Loading capacity (tank) ... C.O.T. 141,783 m3 (incl. Slop T.)
