Newbuild offshore structures are increasing in number and size, creating a virgin market for giant heavy-lift vessels that can transport facilities or carry out offshore dry-docking on location.

The impending completion of Dutch marine contractor Dockwise's innovative semisubmersible Dockwise Vanguard by the end of this year will see this vessel arrive on the market with the capability to be a true "game-changer."

With three transportation contracts already signed, the Vanguard has been welcomed by oil companies looking to speed up the process of transporting their facilities, often halfway around the world. The sums are simple enough – the self-propelled vessel will be able to sail at 12.5 knots to 14 knots from the Far East shipyards to the Gulf of Mexico (GoM), for example, in around 50 days. That is a distance that normally takes around 120 days in a wet tow. Such a crucial cut in sailing time has benefits in terms of bringing fields onstream to begin earning revenue much earlier than currently possible.

image of he Dockwise Vanguard

The Dockwise Vanguard’s movable casings mean it is able to carry fully integrated structures with overhang available on all sides. The vessel’s first contracted job at year-end 2012 will be to transport the Jack/St. Malo semisubmersible platform for Chevron from South Korea to the GoM. (Images courtesy of Dockwise)

According to Robb Erickson, Dockwise vice president, sales for heavy marine transport, the vessel also enables the dry transportation of complete FPSOs and other floating production systems without the need to carry out further work at the other end of the journey. "For FPSOs we can bring the whole thing over from the Far East, topsides and all, rather than do the hull there and the topsides in the West," he said. "This further adds to the time-saving and earlier revenue-generating advantages of using this vessel for such jobs."

He added that a future option might be for FPSOs – "which are just a big box" – to be built without engines instead being transported by the Vanguard to its location for mooring.

The offshore industry's requirement to deploy increasingly large and heavy floating production units (FPUs), not only FPSOs but tension-leg platforms, semisubmersible platforms, and spars, is what drove Dockwise to brainstorm and eventually go ahead with its "Type 0 Super Vessel." With many such facilities weighing more than 50,000 metric tons, the vessels are well beyond the capabilities of the existing fleet of self-propelled semisubmersible transport carriers.

Until now this has led to these FPUs being shipped in segments and then integrated at their destination. "For spars, for example, their own size has been limited by the size of our vessels," said Erickson.

Being able to transport larger integrated structures has the benefit not only of saving time in terms of hookup and commissioning, but it also reduces risks and insurance costs as well as bringing forward first oil or gas.

A grand scale

The sheer scale of the Vanguard is impressive, with a carrying capacity of 117,000 metric tons, a length of 275 m (902 ft), and a beam of 70 m (230 ft). This vessel is the largest semisubmersible ever built and can easily carry ships that are giants in themselves. Erickson pointed out that Dock-wise also is in negotiations with the US Navy over possible applications, including the transportation of aircraft carriers. It also has a 50% larger lifting capacity and 70% greater deck area than the currently largest active heavy lift ship, the Blue Marlin, another Dockwise vessel.

image of the FPSO vessel

The ability to drydock a vessel such as an FPSO or drillship on location will enable operators to avoid any nonoperational downtime, as FPSOs will be able to continue producing while inspection, maintenance, and repairs are carried out. The Vanguard and FPSO will be able to weathervane around the production system’s turret.

To put the scale of the vessel into perspective, the Vanguard's first job scheduled for December this year after its handover from South Korea's Hyundai Heavy Industries is to transport Chevron's large Jack/St. Malo semisubmersible platform hull from South Korea to the Kiewit yard in the US. Erickson said the platform "was well within the capabilities of the vessel."

The second contract currently in 2013 is to transport Eni's circular Sevan 1000-design Goliat floating production platform (with fully integrated topsides) from South Korea to Norway, while its third at present will be to transport Statoil's Aasta Hansteen spar platform in the first half of 2015 to Norway. The latter spar buoy, with an approximate length of 200 m (656 ft), diameter of 50 m (164 ft), and weight of 45,000 tonnes, is "close to the maximum capacity" of the Vanguard, Erickson said.

Other market opportunities

Aside from the transportation options, however, the scale of the vessel also allows Dockwise to pursue other markets previously not possible. The most interesting of these is offshore dry-docking, which the company noted earlier this year at the Offshore Technology Conference in Houston was a major business opportunity.

According to Dockwise, the ship was designed specifically with this in mind, as the ability to be able to dry-dock an FPSO (or drillship) while the unit remains on location is attractive to operators. The FPSO will be able to carry on producing oil and gas while in dry-dock on location, rather than the normal procedure of taking it offline for up to three months while it heads to shore for inspection, maintenance, and repairs, with all the loss in revenues that entails. "We believe dry-docking offshore could be a very big market," said Erickson.

The American Bureau of Shipping in March this year issued an approval in principle to Dockwise for the offshore dry-docking concept. A unique feature of the dry-docking option is that both the anchor lines and the flow risers will remain connected to the FPSO's internal or external turret mooring system, enabling the combined vessels to freely weathervane around the FPSO turret mooring system.

chart - Tech Spec - Dockwise Vanguard

Regarding the revolutionary design of the Vanguard, there is no bow that is more striking, allowing an FPSO for example to overhang beyond both the bow and stern. Its navigation bridge, accommodation area, and lifeboats are situated on the starboard edge of the ship (although the captain also is able to steer from a portable module on the port side if necessary).

The whole design was done with the aim of maximizing cargo space and also features repositionable casings that give it greater flexibility in terms of its cargo-carrying options. Specialist shipbuilding engineering agency DeltaMarin of Finland designed the vessel in detail.

Overall, it allows for large amounts of water to flow along the entire deck of the vessel without there being any chance of water entering the confines of the Vanguard itself. With the ability to sink itself in the water to allow up to 16 m (52 ft) of water above its deck, this first-of-its-kind vessel has a maximum submerged draft that is 3 m (10 ft) more than the existing largest vessel, the Blue Marlin, allowing even larger structures to simply float on before the vessel is raised again.

As the offshore industry continues its journey into deeper waters and remote regions with little nearby infrastructure, other mega-carriers are likely to emerge. Dockwise itself may well opt for a second similar vessel in due course. The cost is not inconsiderable – the Vanguard will cost the company a total of US $240 million. But the rewards, with around $100 million in contracts already received for the vessel and more in the pipeline, are likely to be substantially more.