WTIVS: The future – An owner/operator’s perspective

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Offshore WIND also spoke to the top management of four of the WTIV owner/operators to find out what their views and ideas are concerning the tools of their trade, the wind turbine installation vessels. These four companies are all working in the same market, experiencing the same conditions, both financial and physical. What are the companies experiencing now and how will it affect the future?

A2SEA

Jens Frederik Hansen, CEO at A2SEA A/S, started with the Danish contractor and project shipping company in 2008. A2SEA is co-owned by DONG Energy (51%) and Siemens Wind Power (49%). The company has four self propelled jack up vessels, two of the latest generation of WTIVs.

The SEA INSTALLER was delivered in December 2012, and her sister vessel SEA CHALLENGER will be delivered in the beginning of 2014. A2SEA celebrated the completion of its WTG no. 1,000 installation four months ago.

MPI Offshore

Paul Gibson, CEO at MPI Offshore, and his team were responsible for the first jack up vessel, 10 years ago. This vessel is now named the MPI Resolution and their fleet has since been augmented by two sister vessels, MPI Adventure and MPI Discovery, built as upgraded derivatives of their senior sister.

The three vessels have continued to provide the industry with the top of the range middle to heavy weight capacity, even after the delivery in the past 12 months of the new heavyweight vessels. The company continues planning in many directions for the future.

Seajacks UK

Blair Ainslie, Managing Directory at Seajacks UK Ltd. has brought this company from having two smaller WTIVs 3 years ago, the Seajacks Kraken, Zaratan and Leviathan, to the position where they are today with three WTIVs working at sea and two new vessels being built. Of the new builds, Seajacks Hydra will be in the same class as their first two WTIVs, while the second, Seajacks Scylla, is destined to become the largest WTIV in the world when completed in 3 years time.

Seafox Contractors

Bert van Dijk is the Commercial Director - Renewables at Seafox Contractors. Seafox have vast experience in oil & gas industry. The Seafox 5, delivered late last year, is their first purpose built WTIV. It has a l,200t crane and is one of the largest WTIVs in operation at the moment. Built at Keppel Fels in Singapore there is an option for another vessel to follow.

Learning curve

With so many factors controlling the offshore wind industry: financial, political and technical, the future is difficult to predict, certainly beyond 2016. Until then the four men concur that the current number of WTIVs will be sufficient. They all expect growth after 2016 but how soon after 2016 is difficult to predict.

Even more difficult to predict is what will be required when the next generation is ordered? Productivity of both the existing and the new generation fleet will be an important factor. Track records and experience are not easily earned. The four companies to whom we have spoken do have experience; however each new vessel comes with a new learning curve.

Roughly, in pragmatic statistics, a WTIV's productivity can be depicted as 125 full foundations per vessel, per season; or 250 turbines per vessel, per season. Seafox Contractors looks at the Dutch offshore wind target of 4.4GW for 2020 which on these rates will result in 12 vessel years. But the political determination must remain steadfast, because up to now the 40GW European target rate is not even reaching 50% of the required installation rate.

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One of the companies, Seajacks, has already placed an order for what they see as being the next generation of WTIV. It will tick all the boxes that are known today, for the larger foundations, either jackets or XL monopiles, in deeper waters. The components used for the wind turbines will be heavier and larger, so deck space, lifting capacity has been increased accordingly, as has the ability to carry heavier specialist equipment such as that required for up-ending piles.

WTIV shopping list

Heavier lifts and a higher lifting requirement for nacelles and longer blades are also on the shopping list for the next generation. A2SEA has already covered the need for the increased lifting heights with its new vessels and cranes. The cranes on SEA CHALLENGER (900t) and the SEA INSTALLER (800t) have been designed with the capability to easily extend the boom length when required.

Longer legs make the WTIV capable of working not only in deeper water, but also on differing sea bottom conditions. A soft seabed results in deeper leg penetration levels, and a safe air-gap still has to be maintained.

The Seajacks Scylla will have 115m legs and be capable of working in 65m water, and even with perhaps a 10m leg penetration they will still have a sufficient air-gap. Deck load and deck area, lifting reach, and water depth limits are all factors that will determine the design parameters of the new generation WTIV.

"Six legs - good, four legs - bad" to paraphrase George Orwell's book Animal farm. Four legs may not be bad, but at this moment MPI will prefer to stay with six 'good legs' on any new design. Spreading the weight between six legs reduces the weight of the vessel. They will also go with larger spud cans, 20% larger, on a leg with a wrap around crane installed to control leg penetration.

Not all of the group agreed with this six leg philosophy however, stating that the extra legs occupy much needed deck area and that 4 legs provide better stability when elevated and the jacking cycle is faster with simpler preloading. Nobody had plans for three legs, which works very well for their offshore cousins in the oil & gas sector, a question of deck space, or at least the lack of it!

There is at least one more point that united the group. They all agreed that their vessels, both existing and those to be planned in the future, would load up with their components in port, sail out to the wind farm, install what they had on board and return to port to reload. The question of whether to use feeders and keep these large vessels active in the wind farm remains only a slim possibility because the weather window required for transhipment at sea is too unreliable.

This point raised the question of service speed. To which the answer was that the difference between lOkts, 12kts or 14kts would not be so noticeable in productivity, whereas the extra fuel required to provide the extra knots would be very noticeable. Putting a WTG in place in 8 hours was far more important than saving an hour or two on sailing time.

Improved technology

A2SEA has identified high technology as being a critical factor in safely lifting the nacelles and blades at such heights as will be expected. These vessels are complicated and rely on a lot of expensive high technology to get them working. There are possibilities that cheaper solutions could be found by using more engineering ingenuity in the installation operations.

The amount and degree of technology produces a larger capability but not all of it is needed for every project. However this high tech equipment must still earn its worth even if it is not working for whatever reason.

High working rates come with a high idle rate as well. Bert van Dijk put it bluntly when he told Offshore WIND that foundation vessels could end up being too expensive for turbine installation. Is a compromise between high tech and high rates possible to follow the demand for lower prices and rates in the industry?

Logistics is the key

Turn key operations provided by the WTIV owners are making their vessels more useful. MPI are working on interfield cable laying activities while installing transition pieces, towers, nacelles and blades. Areas of deck space and lower deck storage space are being designed to cater for cable spools and sub-sea equipment. MPI's operations in the future will be total packages with several companies all working together on the same contract.

This approach is the one that GustoMSC were thinking of when they exclaimed 'logistics' as being the most important design factor in the future; designing WTIVs to avoid the bottlenecks and keeping the operation going.

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The prospect of being able to work in an alternative industry, such as oil & gas, is always a fall back opportunity if the vessels are ready for it. A 900t, or larger, crane is an attractive gadget to have for this work. Oil & gas companies offering decommissioning contracts will look favourably on the larger vessels, larger in every dimension as the work moves further North.

Prior experience in the sector, such as Seafox Contractors and Seajacks UK Ltd can provide, will also be appreciated This extra work ability could well speed the financial aspect when placing the building order at the ship yard. Paul Gibson was thinking of the oil & gas sector of the offshore industry when the MPI Resolution was designed.

Unlike the oil & gas jack ups and platforms only a few of the WTIVs have a helideck. One of the reasons for not having one included the fact that it was more useful to have the extra 500t weight as more cargo. It would also avoid all the extra regulatory requirements that helicopter operations would incur. Beside those valid reasons there is one other reason for not having a helideck, and a quite simple one; they manage perfectly well without!

A final interesting point of note is that some of these companies are busy with tenders for contracts for work as far in the future as 2018 - with equipment that does not yet exist! These men, and their colleagues in other companies, are truly men of vision.

Dick Hill

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