Concordia Maritime in Sweden has invested a lot to increase the safety and flexibility of its new tanker concept, the Stena V-Max tankers, and believe its investments will pay. The first of two vessels, Stena Vision, was delivered from Hyundai Heavy Industries Shipyard in Ulsan, South Korea on 24 April 2001. The sister vessel is scheduled for delivery end of June 2001.

Stena Vision is chartered on a 3-year contract by Sun Oil Company. She will deliver crude oil to its Philadelphia refineries on the Delaware river, U.S.A.

The main difference from other VLCCs (Very Large Crude Carriers) is that Stena Vision has several features improving manoeuvrability and reliability for safer operations in narrow waterways. The vessel has been built to DNV Class. It is the first time Hyundai Heavy Industries (HHI) has built this kind of ship and it has been a challenge for all parties involved.

Loss of control eliminated
According to Lars Carlsson, Concordias Managing Director, the new concept has eliminated the risks of losing vessel control due to machinery and system failures, cause of more than 30% of serious tanker accidents. Using only one of the twin engines, the ship can manoeuvre for at least 72 hours at a speed of six knots in a head sea and winds of Beaufort force 8. This reserve of power makes the new vessels the first VLCC tankers to satisfy DNVs special class notation RPS (Redundant Propulsion and Separation).

Shallow draft
With a beam of 70 m (58-60 m is normal for a VLCC) and an extremely shallow draft of only 16.76m, the vessel is tailor-made for ports with draft restrictions. Lightering operations at sea and transfer in intermediate ports are costly and time-consuming, but with this design can often be reduced or avoided.

Redundancy and separation of propulsion and steering
The vessel is equipped with a double set of main engines, rudders, steering gears and propellers. The two engines are in engine rooms completely separated from each other with fire- and watertight division. The vessel has also redundant remote control system and propulsion support systems.
In case of fire or flooding in which one engine room is lost, the vessel will still be able to operate with one propulsion and steering system in operation. Arrangements are made to compensate for a possible loss of the Engine Control Room.
Through the solutions developed for the Stena V-Max vessels, the RPS notation has been evaluated. Adjustments are being made to make it even more attractive to owners and yards building vessels with extra focus on safety, redundancy and flexibility.

Propulsion systems
The propulsion system on board the vessel is unique for a VLCC, thanks to the redundancy and use of special components. To reduce the propeller revolutions per minute, thus giving a more cost-effective operation, each main engine is geared down from 105 to 66 rpm. The Schelde Gears have integrated clutch with soft clutch-in characteristics. Repair and maintenance can be done on one propulsion line with the other side still operating. In addition, a special Vulkan elastic coupling with progressive characteristics is installed between each main engine and the reduction gear to dampen harmful impacts.