High-Capacity Subsea Vessel That Refuses to Accept Failure

Ulstein Group has joined forces with GC Rieber Shipping to offer the market a new standard in operational security and performance – a ship that refuses to accept failure, thanks to the pioneering ‘operation+’ philosophy.

GC Rieber Shipping, the Norway-based harsh environment shipping specialist, has charged ULSTEIN with developing a high-capacity subsea vessel based on its SX121 design. This NOK 800 million (approx USD 137.7 Mln) ship, ordered in June 2012, alongside an option for a sister vessel, has been commissioned in response to strong market desire for offshore construction support vessels (CSVs) for deep and harsh environments.

Reliability in the extreme

Alongside state-of-the-art features, equipment and performance figures, the vessel will give GC Rieber Shipping maximum operational availability – a vital characteristic for both the company and those chartering the ship. Downtime will be minimised thanks to the ‘operation+’ feature, an evolution of GC Rieber Shipping’s own ‘fail-to-safe’ design approach.

‘Operation+’ allows the vessel to continue to operate even if it has experienced a significant failure. Bjørn Valberg, GC Rieber Shipping’s Technical Director, explains more:

“Fail-to-safe means that even if a ship encounters a failure it is rendered in a safe condition. Our objective with this ship is to take that philosophy a step further,” Valberg comments. “In the case of this vessel a single failure – such as a failure of a generator set, a single thruster or even an entire switchboard section (operating two generators and two thrusters) – will not threaten the redundant continuation of operations, giving charterers real peace of mind.”

Configured for success

ULSTEIN’s design and solutions team has been working to turn this concept into reality and deliver the Holy Grail of minimal operational downtime and maximum efficiency and reliability.

Geir Sivertstøl, principal engineer electrical systems at ULSTEIN, says that the vessel, equipped with three main thrusters and three side thrusters (for stationkeeping during pipe laying), is fully optimised for carrying out assignments without interruption. ”The switchboard system, propellers and diesel motors can be configured in groups of two, three or four. In case of an AUTR operation (i.e. the occurrence of a single major failure), the vessel will only lose one third of its installed power package and propulsion, and will be able to complete the operation with two thirds of its capacity. This in combination with the highest standards for dynamic positioning, DYNPOS-AUTRO, will ensure that charterers can look forward to operational standards that are custom made to tackle the world’s harshest – and potentially most resource rich – environments.”

Equipped, flexible, compelling

GC Rieber Shipping’s version of the SX121 (yard number 300 at Ulstein Verft) has been equipped to meet the most diverse requirements, in the most demanding of conditions.

The 130-metre long, 25-metre wide vessel can accommodate a crew of 130 and cut through deep waters with a top speed of 14.5 knots, while meeting all the latest environmental standards. She is equipped with a powerful 250 ton AHC (active heave compensated) offshore crane, perfect for lifting and lowering heavy equipment to and from subsea environments.

A large cargo deck creates the optimal environment for a variety of operations, ensuring that the vessel is well placed to meet the hugely diverse demands of the offshore construction market. It also offers the ability to carry two ROVs (remotely operated vehicles) – one that will be launched from the starboard side and the other through a moon pool.

In addition, the ship has been designed with SURF (subsea umbilical riser and flowline) capabilities and is prepared for the installation of a below-deck basket/ carousel with a 2500 ton capacity, as well as a 250 ton VLS (vertical lay system) for deployment through the moon pool.

Delivering promises

GC Rieber Shipping’s vessel is, according to Tore Ulstein, deputy CEO in Ulstein Group, the ‘perfect project’ for ULSTEIN to show its renowned design and shipbuilding pedigree. Tore Ulstein notes that the business is well accustomed to developing and producing vessels that have the capability to minimise operational downtime, maximising customers’ profits. “Our organisation has broad expertise in developing advanced high-capacity offshore vessels together with customers, so this project suits us perfectly.”

The SX121 is scheduled for delivery in the first quarter of 2014, boosting GC Rieber Shipping’s fleet (which was fully booked at the conclusion of 2011) of 18 advanced special purpose vessels, 12 of which are owned by the company.

[mappress]

Shipbuilding Tribune Staff, August 28, 2012; Image: ulsteingroup