Super Vessel To Carry Up To 110,000 Metric Tons

E&P is shifting from shallow water to extremely deepwater fields, which calls for the deployment of very large floating production units (FPUs). In addition, growing interest in exploring remote areas that have no integration infrastructure requires larger and heavier equipment to be built as completed integrated units. Being able to move these larger structures to the point of operations broadens horizons for the E&P market and delivers significant cost benefits at the same time.

Extremely large structures such as tension leg platforms (TLPs), semisubmersible platforms, and gravity-based structures with a dead weight of more than 50,000 metric tons outweigh the capacity of existing self-propelled semisubmersible transport carriers. This means these types of FPUs have to be transported in segments that are integrated at the destination, resulting in both a time- and cost-consuming schedule. The same applies to large newbuild FPSOs and semisubmersible crane vessels that still depend on tug power and a towline.

From the very early introduction of self-propelled, semisubmersible heavy transport vessels, heavy marine transport specialist Dockwise realized transport capacity is a significant factor in the industry’s approach to construction and mobilization. Being able to transport larger integrated structures creates more freedom in the choice of a construction site. Moreover, it substantially saves on costly onsite man-hours for hookup and commissioning, and reduces risks and insurance costs. In many cases, the bottom line is that it also contributes to reducing the time to production.

Meeting an industry need

To address these industry requirements, Dockwise has begun building a vessel that exceeds the capabilities of any vessel in today’s market.

In late 2012, Dockwise will add the twentieth vessel to its fleet of semisubmersible carriers. Construction has started on what the company refers to internally as its “Type 0 Super Vessel,” a unique heavy transport ship with a deck size of 275 m by 70 m (902 ft by 230 ft), a revolutionary bowless design, and a carrying capacity of more than 110,000 metric tons. A vessel capable of carrying structures of truly extreme dimensions has the potential to change the way offshore structures of this scale are designed, built, integrated, mobilized, and installed on site. South Korea’s Hyundai Heavy Industries (HHI) is building the vessel, which is scheduled for delivery in 4Q 2012.

More than just an addition to the company’s fleet, the mega carrier is designed to overcome scale limitations, and in doing so, creates new opportunities for exploration, production, and processing in deepwater fields and remote areas.

Vessel design

The Type 0 Super Vessel will stand out in the Dockwise fleet not only by sheer size and carrying capacity, but also because of its revolutionary design characteristics. The accommodation block and navigation bridge are on the extreme starboard, which allows cargo to protrude on all sides of the carrier. And the vessel has no bow, which has allowed the company’s engineers and naval architects to stretch the limits of transport capacity by implementing optimized deck strength, extreme wind load capabilities, and stability characteristics to carry state-of-the-art semisubmersible production structures in line with the latest air-gap requirements.

The company pursued the Type 0 Super Vessel design without compromise, pushing for the best solution from the standpoint of cargo and with a view to achieving optimum propulsion, safety, strength, ballasting, and flexible deck space. With two diesel-electric main propulsion trains and two azimuthing thrusters, the new carrier will be able to achieve a top speed of approximately 12 knots fully loaded with unprecedented stability characteristics and excellent maneuverability to ensure maximum safety to the cargo.

The concept uses the vessel’s deck dimensions to the fullest measure and offers maximum flexibility in loading procedure and cargo stowing. No other self-propelled vessel of this class exists to date.

With the ability to submerge to a depth of 16 m (52.5 ft) of water above deck, the Type 0 Super Vessel will not only serve transport demand for the largest types of cargo, it also will cater to cargo types with specific characteristics or requirements. The company expects the vessel to be the ideal carrier for transporting 5th and 6th generation semisubmersible rigs in great part due to the increased maximum submerged draft of 16 m, which is 3 m (10 ft) more than the largest existing vessel, the Blue Marlin, also a Dockwise vessel. A relatively high vertical center of gravity will allow cargo to better fit on the new vessel as well.

The new vessel redefines the boundaries of what can be transported and opens opportunity to rethink approaches to integrated builds that previously were far beyond the industry’s reach.