If you’ve been near Weybourne on the north Norfolk coast recently, you’ve probably noticed a strangely shaped vessel that looks like it’s on stilts just offshore – and are wondering what in the world it’s doing there.

It’s an offshore jack-up installation vessel playing a critical role in the UK’s green energy transition.

The Haven Sea Challenger jack-up barge is helping to create the vital link that will connect the renewable energy generated by Ørsted’s Hornsea 3 offshore wind farm 120km off the Norfolk coast with millions of UK homes.

Above the waves

Hornsea 3 will have a generating capacity of 2.9 gigawatts – that’s enough green electricity to power over three million UK homes.

But first, all that green energy needs to be brought onshore and connected to the National Grid.

That’s where the jack-up barge comes in.

Jack-up installation barges are equipped with legs to lift them above sea level. Standing firmly above the surface of the water, the vessels can operate safely and securely without being impacted by currents and waves.

The Haven Sea Challenger jack-up barge is off the coast of Weybourne to create a stable platform for the installation of the offshore cable ducts, or pipes, that will transmit the green electrical power generated offshore by Hornsea 3 to land.

Four cable ducts will be installed using a technique known as horizontal directional drilling. The construction method involves drilling tunnels under the ground and seabed, so that the cable ducts can be pulled through.

The technique avoids some of the surface disruptions caused by traditional open trenching. The same process is being used along the onshore cable route.

Environmentally friendly process

Jamie Priestley, Ørsted‘s senior project lead for the landfall aspect of the horizontal directional drilling, has 25 years’ experience with the technique and worked on similar installations for Ørsted’s Hornsea 1 and 2 offshore wind farms.

“We’re installing the connecting onshore and offshore ducts in an environmentally friendly way by drilling from land to sea, to allow the cables to be transitioned between them,” said Jamie.

“Our aim is to work safely in conjunction with the local community and the landowners,” added Jamie, who lives three miles down the coast from the installation point in Sheringham.

Stephen Start, the offshore installation manager, ensures the project is following approved procedures and remains compliant with the statutory requirements set out by the Marine Management Organisation and Natural England.

“My primary role is to work with our contractors and their subcontractors to oversee the installation process, ensuring adherence to safety procedures, quality standards and the environment. To make sure we have people doing the right things, for the right reasons and that everybody goes home safe every day,” said Stephen.

With over 40 years’ experience working in offshore energy, first in oil and gas before switching to renewable energy about 15 years ago, Stephen has worked around the world from Scotland to Singapore and the US.

Collaborating with local and UK-based suppliers including Red7 Marine, the Suffolk-based company providing the jack-up barge, and AMS, the horizontal directional drilling experts based in Scunthorpe, is an important part of the project.

“We’re on a superhighway to develop bigger and better wind farms in the UK. We can only do that if we share our experiences, engage with local businesses and give them the opportunity to shine,” he said. “Everyone can be a part of a greener, more sustainable way forward.”

An engineering feat

The jack-up barge’s work is aiming to be complete by the end of September.

While the jack-up vessel may be a curious object to paddle boarders, kayakers and jet skiers, it is an active work area and for safety reasons should not be approached by onlookers.

“We would really ask the public not to approach the jack-up barge,” said Jamie. “There are diving activities and mooring lines that people could get tangled up in – and we really don’t want people to approach it.”

So please continue to observe this engineering feat enabling the green energy transition from afar.

For more information, please visit hornseaproject3.co.uk