Scroby Sands Offshore Wind Farm celebrates 20th anniversary

Commissioned in March 2004, RWE’s Scroby Sands Offshore Wind Farm was one of the UK’s first commercial offshore wind farms. It has an installed capacity of 60 megawatts and has been powering the electricity needs for the equivalent of all the homes in King’s Lynn (48,000) for two decades.

Located on the Scroby Sands prehistoric sandbank in the North Sea, 2.5 kilometres off the coast of Great Yarmouth, it was one of the first of a group of projects to be built in coastal locations with relatively shallow waters close to shore.

The 30 turbines are located in water from 13 to 20 metres deep. Each turbine has three 40-metre blades that rotate around a centre-point some 60 metres above the mean sea level.

The Jumping Jack jack-up platform (Image: CHPV)
“However, due to natural changes in the marine environment and coastal erosion, the sandbank has risen over time, effectively isolating four turbines from being accessed by service vessels,” explained Phillip Croston-Clegg, Scroby Sands’ general manager.

“To that end, RWE, in partnership with Commercial Rib Charters (CRC), initiated an offshore wind revolution, with the innovative design and build of a world-first amphibious crew transfer vessel for reaching offshore wind farms in shallow waters.

“The unique vessel, named the CRC Walrus, it is a fully seaworthy crew transfer vessel, which can also drive on land, providing a unique access solution for some of the industry’s first-generation assets affected by very dynamic seabed conditions.”

Technicians working on the installation of the turbines (Image: CHPV)
A fire in the nacelle of one of the turbines in August 2023 resulted in the loss of that turbine. The decision to remove or re-plant the affected turbine is not yet confirmed. RWE is reviewing technical solutions for both options due to the complex and amphibious nature of the specific location.

All remaining turbines continue to be operational.

As RWE celebrates Scroby Sands’ 20th birthday, it is reviewing what the next five years for the wind farm will look like, and its end-of-life management.

In addition to Scroby Sands, RWE has an extensive portfolio of offshore wind projects in East Anglia: three operational sites and five projects in development, including the recently acquired Norfolk Vanguard East and West and Norfolk Boreas projects.

The amphibious CRC Walrus was launched early last year (Image: RWE)

RWE pioneers world first at Scroby Sands

Scroby Sands sparked an offshore wind revolution with the innovative design and build of a world-first amphibious vessel for reaching offshore wind farms in shallow waters.

The unique crew transfer vessel was initially designed to reach turbines at Scroby Sands, which have become stranded by the natural rising tide of the sandbank on which it is built. 

The CRC Walrus took its maiden voyage in early January 2023 with positive results, achieving speeds of 24 knots on water and 6 km/h on land. 

The 12-meter vessel has a 1,000kg cargo capacity and is capable of safely transferring 10 technicians and two crew to any of the turbines within the Scroby Sands array, including on the raised sandbank. 

The design means that the two wheels at the front and one at the back can be deployed, similar to an aircraft, when transferring from deeper water into shallow water and sand. 

Sven Utermöhlen, CEO of offshore wind at RWE Renewables, said: “The new amphibious maintenance vessel at Scroby Sands is really exciting; it’s a great testimony to the talent of our employees and contractors, and once again demonstrates RWE and its partners leading the way in future-proofing offshore wind. 

CRC Walrus has enabled access to the four turbines on Scroby Sands that have been stranded by rising tides (Image: RWE)
“Innovation is a critical part of the energy transition, supporting the growth of the offshore industry and ensuring the long-life operations of our offshore wind fleet in the UK and around the world.” 

The fully seaworthy vessel, which can also drive on land, provided a unique access solution for some of the industry’s first-generation assets affected by very dynamic seabed conditions. 

Natural changes in the marine environment and coastal erosion effectively isolated four turbines from being accessed by service vessels.

The bespoke solution was jointly developed in record time between RWE’s operations team, its technical innovation team and its vessel provider Commercial Rib Charter (CRC), which contracted naval architects Chartwell Marine to carry out the design to the specifications requested. 

The vessel was built by Isle of Wight based boat builders Diverse Marine, and is operated for RWE by CRC on a six-year contract.  

The fully seaworthy vessel is named ‘CRC Walrus’ in honour of R.J. Mitchells’ classic 1930s Supermarine amphibious biplane.

Capturing the magic from the start

When offshore photographers and filmmakers Alan O’Neill and Andrew Pinder went off Great Yarmouth to capture the construction of Scroby Sands, they had to hire a fishing boat because crew transfer vessels didn’t exist.

Alan O'Neill, owner of CHPV Offshore Film and Photography (Image: CHPV)
“It took about an hour to get out there. When we got there, we climbed on to the transition piece (TP),” explained Alan.

It was one of the first offshore wind farms that Alan and Andrew photographed and filmed. This year, Alan’s CHPV business marks its 60th anniversary, having photographed and filmed on offshore gas assets as well as being involved at the start of the wind industry. 

In the days before drones - now standard kit for CHPV - they had to take a helicopter to fly over the wind farm.

Andrew Pinder (Image: CHPV)
For further filming, they went out on the Jumping Jack jack-up platform, which is still working now as Sea Jack in Greece.

“In those days, the turbines were installed in just three lifts compared to six today,” said Alan. “Towers were installed in one piece then the whole nacelle with two blades in one go.”

For further information on RWE’s portfolio, visit uk.rwe.com/our-energy/offshore-wind/