What will the wind support vessels of the future look like? Stevie Knight finds out that it’s all surprisingly close.
Imagine an unmanned cargo boat. This has the advantage of being able to nip back and forth from base in conditions that a crewed vessel carrying technicians wouldn’t dream of.
Sounds too far-fetched? In fact, it’s almost here: Denmark’s Tuco Marine Group, working with Sea Machines, are just about to launch a remotely operated demonstrator.
The interesting point is that while it might sound groundbreaking, it’s firmly based on known technology: the 12m ProZero Light Pilot: “All these boats are fly-by-wire,” explained Jonas Pedersen of Tuco. “It means that you don’t need a mechanical interface - you can plug right into the steering so it’s not a big step.” This daughter craft could be piloted remotely from the mother ship or a landside base, or guided in by an operator on the tower, the cargo being plucked off by the turbine’s crane using a heavy lift magnetic or suction grab like those used in the production industry.
Even more groundbreaking are the truly autonomous craft under development by the likes of BAE Systems, ASV Global, Rolls-Royce, and Kongsberg: this last sees the arena as an extension of its own dynamic positioning and control systems. Kongsberg’s tech is being utilised by the Automated Ships project for a world first: Hrönn, is a 35m utility vessel aimed at the offshore energy sector which should be launched by the end of next year. For those worried about safety, it’s worth noting these craft include sophisticated AI, “object recognition” software fed by cameras, LiDar, infrared, radar and so on - and can tell the difference, say, between a floating log and a small boat. Given something outside their experience, they’ll throw a request for help back to base where a pilot will take a peek through the vessel’s cameras... and they have the ability to learn from each encounter.
Inside the engine room of the future, electrical power wins – some with a hydrogen fuel cell which keeps ticking away in the background, supplying an energy top up. The fact is that batteries can respond to dynamic seas much faster than a combustion engine: electrical power being much better suited to the touchy business of navigating around wind farms and locking onto towers (yes, that will change too).
Heavy R&D and sharp competition has already dropped footprint, price and raised battery power density dramatically, years ahead of predictions – and new chemistries that promise even more should be off the testbed and into production inside the next decade. Hydrogen looks like catching up – at present there are a number of lightweight composite tanks suitable for holding the gas under pressure, though as it’s also possible to create hydrogen from water using electricity, these systems could advance enough in the coming years to make onboard installation plausible.
There’s a trend to try to take technicians off the towers wherever possible, so WFSVs might gain a drone deck. At the end of last year, Cyberhawk carried out close visual inspections of three of TenneT’s converter stations, dropping the entire project time by more than half to just a week.
This summer Esvagt partnered up with inspection specialist AtSite, its SSV Champion acting as a base for drone inspection of the 80 towers and blades that make up the BARD Offshore 1 farm. According to Esvagt, examinations that normally take up to a whole day were cut down to around 25 minutes per turbine. Moreover, no one had to get up a ladder in the North Sea.
Surprisingly, the weather limits are rather wider for drones than you might expect: René Merrild of inspection specialist AtSite says, they can be launched and recovered in over 2m significant wave heights, even potentially coping with double that depending on vessel size: Most importantly they can deal with 12m p/s winds, more with a programme tweak.
However, personnel transport will still be needed and the human factor has started pushing an evolution below the waterline: designers are working hard on alternative hulls for longer journeys and rougher seas.
For example, there’s a self-levelling innovation from Australian Nauti-Craft. The deck sits up on passive, linked hydraulic chambers and these ‘legs’ react individually to the sea’s surface, evening out rolling and pitching motion; the vessel also corners better at speed than a standard cat – the effect being reminiscent of a skilled water skier. The design allows adjustment for various sea states and load conditions and another, active system maintains the horizontal attitude of the deck with a special mode for approaching turbines or other low speed manoeuvres.
Then there’s the idea of floating the vessels, not on water, but on air. Some Surface Effect Ships (SES), like Umoe Rapid which came to Seawork 17, have a roughly similar shape to a catamaran, but Umoe has blocked off the tunnel between the hulls, putting flexible rubber seals fore and aft.
This space holds a cushion of air blown under the vessel by lift fans; as a result the boat sits high in the water, presenting less drag. Further, the pressure can be managed to dampen motion during high speed transits as well as during engagement with the towers. They are certainly fast: both the 26.6m Umoe Firmus (which has been working at Sheringham Shoals) and Rapid are capable of speeds up to 42kn with a transit of around 38kn. More, they are stable: builder and designer Umoe Mandal say these vessels can take on landings in 2.5m wave heights.
But what about the overall efficiency picture? Counter intuitively, while those pressurized fans do require a substantial amount of energy, the reduction in resistance at high-speed actually adds up to a lower installed power than on an equivalent monohull – and according to crew reports, it’s actually quieter too.
By Stevie Knight
