The solution

Orbital, in collaboration with the University of Edinburgh, chose our Origin 600 ADCPs to collect high-quality current and wave data around the O2 turbine at EMEC’s Fall of Warness site.

This would help them both characterise the site and calibrate their computational models.

Our Origin 600 ADCP enables users to monitor waves, currents and turbulence in high-energy sites.

“Its built-in acoustic modem provides remote access while deployed, letting teams check battery and memory, inspect and upload data, adjust schedules, and run quality control—without recovering the instrument—supporting time-critical decisions with near real-time delivery,” says ADCP group manager Tom Culverhouse.

The ADCPs were positioned and orientated as shown below. The goal was to position one ADCP upstream of the O2, as a control, and the other three ADCPs downstream of one of the rotors to investigate the effect of the wake induced by the rotor:

Easy and accurate positioning and heading for ADCPs

Historically, ADCPs have been deployed at sites such as EMEC with locations estimated from deployment vessel position and orientation from an onboard magnetic heading sensor.

This typically results in positional accuracies as low as tens of metres and magnetic orientations that can suffer bias (e.g., by nearby electricity-carrying subsea cables).

Recognising these limitations, one of our Ranger 2 Ultra-Short BaseLine (USBL) positioning systems was used during deployment and recovery. This was with a Gyro USBL transceiver, which, thanks to its integrated AHRS, comes pre-calibrated for easy installation as well as optimized positioning.

This system provided the location of each bedframe to within ±2.5 cm – a much better result than the tens of metres typically achieved.

“As each Origin Seabed Lander contained two release beacons, and each ADCP was mounted in a fixed orientation relative to the bedframe, these could be used by the USBL to derive the lander heading acoustically,” adds Culverhouse.

“This resulted in ADCP heading uncertainty of ±3˚and – critically – free from systematic magnetic effects of nearby chains and cables.”

Having deployed, positioned and orientated the bedframes successfully, the ADCPs were left to gather data for one month – sufficient to measure currents and waves over a full lunar tidal cycle.

The deployment period included extreme weather conditions as Storm Floris passed through, resulting in highly dynamic near-surface data observed in the ADCPs!

The results

The devices were recovered using the integrated RT-6 1000 acoustic releases and pop‑up buoys. Following a month of exposure to extreme subsea conditions, all acoustic releases functioned correctly, allowing seamless recovery of every lander.

This demonstrated the robustness of the full Sonardyne integrated technology stack, including the bedframe, acoustic releases, popup buoys, external ADCP batteries and the ADCPs.

“Measuring the wake from a turbine in the highly dynamic tidal environment is a real challenge,” says Calum Miller, Chief Engineer and Design & Innovation Manager at Orbital. “In particular, we needed to be able to deploy the instruments within a small target area at c.45m depth with a specific heading, and to be able to confirm that the installation tolerances had been achieved in real time.

“The integrated solution offered by Sonardyne was the perfect tool for the job and the Sonardyne team gave us all the support we needed for a successful installation and measurement campaign.”

The image below shows just a few hours of data from one of the four ADCPs, showing currents of up to 4.5m/s.

Each Origin 600 ADCP was able to profile water velocities from the seabed to the surface. An example of this is shown below, where a five-minute burst of data during Storm Floris causes rapidly changing velocity fluctuations near the surface at about 46 m.

Brian Sellar, Associate Professor in the School of Engineering at the University of Edinburgh, says, “This collaboration with Sonardyne and Orbital Marine Power is an important part of our ongoing efforts to assist the tidal energy sector in the roll-out of large-scale tidal energy.

“This field work, led from our side by Nairn Spence an EPSRC Case PhD student co-funded by Sonardyne shows the value of partnership, developing improved methods and exploiting great tools. We would like to thank EPSRC and Crown Estate Scotland for funding support and Edinburgh Innovations and Leask Marine for their services.”

“Working in energetic tidal sites like the Fall of Warness is operationally very challenging,” adds Nairn Spence, PhD student at the University of Edinburgh. “Wakes are relatively narrow features within the water column, so accurate placement and orientation of our ADCP bedframes was essential.

“The integrated positioning capability of the Sonardyne systems enabled us to guide the instruments rapidly and precisely onto their predefined locations during the short slack-water windows available.

“At this site, there is typically around a one-hour slack water period to operate every six hours, and deployment is only possible during neap tides, a two-to-three-day period in the roughly 14-day spring-neap cycle. Being able to mobilise the system quickly on the operations vessel, without losing additional days in port for set-up and integration, made a significant difference to the success of the campaign.”

“This campaign was designed to measure the effect of the wake and to calibrate a site model developed by the University of Edinburgh to the measurements made by the ADCPs,” adds Culverhouse. “We look forward to their upcoming publications that will provide scientific analysis of the data and compare the measurements to sophisticated computational site models.

“This work will provide greater insights and guidance for measurement requirements for environmental regulations and help inform site operators such as Orbital on maximising the commercial potential of their sites.”