United Kingdom

United Kingdom

Vessel designers start to find their sea legs

Vessel design and availability can greatly influence the viability of the offshore wind power sector, as the combined effect of Round 3 progress and 2020 targets propel developers into ever-deeper waters. We report on how one firm tackled the innovation challenge

passengers need to be looked after and kept entertained to maximise their productivity upon arrival on site.
passengers need to be looked after and kept entertained to maximise their productivity upon arrival on site.

This year has seen the completion of two major UK Round 2 offshore wind farms, Sheringham Shoal and Greater Gabbard, off the East Anglian coast as well as smaller farms such as Ormonde, in the Irish Sea. While there has been significant progress around the UK and Europe on near-shore projects, it is time for projects further out to be kicked off. Developers and the supply chain are now turning their attention in earnest to this challenge.

One of the central issues is the supply of vessels equipped for safe, cost-effective operations far offshore. This is a problem across the board, whether you are looking at site survey, crew transfer, flotels, motherships or jack-ups. The lead time from order to delivery can be as long as the construction of a wind farm.

This itself presents a dilemma. Who will invest in building specialist vessels without the guarantee of a return? Who would charter a new design without proof of the concept working in the real world? Who will provide the finance for a first-in-class or innovative design without seeing a contract for its use?

With our experience of the challenges posed by the expansion of offshore wind, lets us focus specifically on the smaller vessels that are needed for crew transfer, surveying, and maintenance and servicing.

Potential of smaller craft

Sea states and weather conditions restrict access of personnel for installation, commissioning and maintaining of the met masts, turbines and substations. The designs of these offshore structures limit the size of craft that can dock in with them, while vessel build costs — and therefore charter rates — escalate quickly with larger vessels that may be equipped with dynamic positioning and motion-compensating gangways.

We need to go back to the drawing board to work out what can be achieved from smaller crafts and how those abilities match the requirements of developers or utilities.

Our market research has thrown up significant shortcomings in many of the vessels being used for crew transfer. Additionally, the vessels were being managed poorly, without enough preventive maintenance to provide the charterers with the day-to-day reliability that they expect. Therefore we sat with the naval architects at Mercurio Group in Spain and laid out our demands (see box).

Research bears fruit

The results of our research, combined with our knowledge of the marine environment, informed our work as we began to design vessels tailored to the specific needs of the offshore wind industry.

The boats we have built so far are named Ginny Louise and Eden Rose (with Tia Elizabeth to follow shortly). Each is 20 metres long with an eight-metre beam, and both are regularly transferring passengers at wave heights in excess of 1.5 metres. We have even transferred passengers in 2.5-metre swell more than 70 miles from safe haven — Maritime Coastal Agency (MCA) Category 1 waters — with less than one rung of movement on the ladder.

Both boats are financially competitive with vessels in the industry thanks to glass-reinforced plastic rather than aluminium construction. Their lower weight leads to significant savings in capital costs and fuel. Mercurio’s patented and innovative hull design has eliminated most of the transit slamming typically found in catamarans. The addition of RG Seasight fenders allows the boats to grip tightly to landings for transfers.

The two vessels are able to carry ten tonnes, loaded using their own cranes, have a dedicated survey room with access to a moonpool and can be used for any task from bird watching to turbine servicing.

They are MCA Category 1-coded to operate up to 150 miles from safe haven, easily encompassing the UK’s Round 3 projects. There are beds for 12 passengers and up to four crew so they can stay offshore for as long as the four fridge-freezers can sustain them.

While the two vessels may not be the definitive solution to Round 3 operations and maintenance, they represent an innovative step forward that goes a long way to meeting the requirements that we laid out.

Now that our growth plans are clear and the proof of concept has been delivered, attracting finance at the right terms is essential to realise the plan.

Cooperative planning

If the shortage of appropriate vessels is to be resolved then developers and utilities that need vessels, but do not wish to own them, must work with the vessel owners to increase their fleets.

It is up to a vessel owner to prove a concept but once this is done, the client needs to step up to the plate with a long-term contract — a minimum of one year but preferably three to five years. This will allow the vessel owner to go to the bank to borrow against secured income.

Option periods are worthless as these can further restrict the vessel owner from securing other, longer-term contracts. In today’s world, no bank wants to end up with a second-hand boat as security.

Longer contracts are beneficial to all parties: longer charter periods mean cheaper charter rates. If we all need to cut costs then let’s work together.

Leo Hambro is director of marine transport firm Tidal Transit

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