A trial to understand the dynamics of cable movements in floating offshore wind installations provided the opportunity to also trial real-time measurements (logged every 20 minutes) of waves and currents using an Origin® 600 Acoustic Doppler Current Profiler (ADCP) in the same location. This blog examines the results of the trial and looks at how Origin 600 could be utilised for other similar applications.

Introduction

France Energies Marines (FEM) is a French institute for energy transition dedicated to offshore wind energy. The institute operates as a public-private collaboration bringing together around 30 entities from academia, government, and industry, including energy specialists, developers, manufacturers, and engineering firms. It conducts R&D projects and runs long-term sector-focused programs, transferring their findings to offshore wind stakeholders through research services, licensing and consultation.

The institute maintains a national presence with strategic locations across French coastlines to support both bottom-fixed and floating offshore wind development. It plays a key role in France’s goal to become a leader in green hydrogen and renewable energies by 2030, having already completed over 35 projects and operated €10 million in funding during its early years. FEM, working in collaboration with a number of partners, conducted a floating offshore wind farm (FOW) site characterisation trial in the Bay of Douarnenez, South of Brest, France over a four-day period in July 2024, using Sonardyne equipment supplied by our reseller, Cadden.

The deployment site was chosen for its similar characteristics of offshore wind sites and good accessibility. The FOW trial report can be read here. While the FOW trial was taking place, the opportunity was taken to also deploy an Origin 600 to monitor waves and currents at the same location. The site had a nominal depth of around 33m; with a maximum current profiling range of over 60m, Origin 600 was therefore ideally suited to this task.

Approximate location of the trial in the Bay of Douarnenez, France.

Equipment

Origin 600 was mounted in a gimballed Mooring Systems Inc. (MSI) tripod bedframe, along with dual RT 6‑1000 acoustic releases, rope canisters, and popup buoys for recovery of the equipment. The bedframe was lowered to the seabed using the vessel winch line and released using an RT 6-3000 acoustic release; the full equipment set is shown in the image below.

Origin 600 was first calibrated at quayside to ensure that the internal magnetic heading sensor would report accurate bearings. Site-specific metadata such as depth, latitude, longitude and sound velocity were entered to the device to provide comprehensive auditing of the data post‑recovery. The ADCP was then configured to ping at 4Hz continuously for the duration of the trial.

Data Analysis

Origin 600 was configured to log industry‑standard PD0 data, alongside proprietary high‑fidelity A‑gram data. On recovery of the device, Origin Viewer software was used to provide a simple quality check of the data. Log files were downloaded from the ADCP and read into Origin Viewer for visualisation and inspection. Although this deployment was of short duration and produced a relatively small volume of data, Origin Viewer is capable of quickly rendering heatmaps of up to 1 terabyte of A-gram data. So, whether for small surveys like this one or deployments for months at a time as part of an intensive measurement campaign, the Origin ecosystem supports operations of differing lengths and intensities.

Screenshot from Origin Viewer showing heatmap of current bearing over four days and the tidal cycle.

In addition to simple data logging, Sonardyne’s Waves Edge application was installed on the ADCP prior to deployment to process and report directional and non-directional wave data as it was acquired. This is a textbook example of the utility of Sonardyne’s Edge computing environment, a general‑purpose and user‑customisable means to deploy custom in‑situ data processing on all Origin ADCPs.

The Waves app in particular allows users to both monitor currents and waves in real‑time and harvest the processed results as acoustically downloadable data files, allowing mid‑deployment insights of the subsea environment to be gained without the need to recover the instrument.

For currents, the app computes the mean average current in the central 50% of the water column. This vector average is then itself ensemble-averaged at 20 minute intervals. Figure 2 shows the output of this process for the duration of the trial. The twice daily (semi-diurnal) tidal cycle is clearly observable, and the overall current speed at the site is around 10cm/s. This is ideal for offshore wind sites as low currents means less stress on infrastructure and scour around the monopiles and cables.

Figure 2: Current measurements during the trial: Top is (horizontal) current speed, bottom is current bearing.

For waves, like currents, the app accumulates data and computes average wave properties every 20 minutes. Figure 3 shows the significant and maximum wave heights calculated by the app over the duration of the trial. While the significant wave height generally does not exceed 0.8m, the maximum wave height rises above 1.6m on occasion. On average, both quantities increase steadily with time, approximately doubling over the measurement campaign. This demonstrates that even on relatively short timescales there is a need to continuously monitor such parameters, which can impact offshore safety‑critical logistics such as crew transfer operations.

Figure 3: Significant wave height (purple), and maximum wave height (orange), for the duration of the trial.

Equally significant wave parameters are the peak wave period and their direction (noting that the convention for waves is to report the direction from which they arrive, rather than the direction to which they head, unlike currents). These are shown in Figure 4, both as simple 20 minute averages, and over a one hour averaging window. This data demonstrates that Origin 600 can accurately and operationally track such parameters, which are important not only for crew transfer, but also operational maintenance of infrastructure which may be degraded over time by wave action.

Figure 4: Surface wave peak period (top) and bearing (bottom). Blue shows the 20 minute average, purple shows a windowed one hour average for each quantity.

The analysis above shows that Origin 600 can measure these parameters accurately, providing operators with mission‑critical information they can trust. Furthermore, this processed data can be reported through the integrated acoustic modem: Two modes of operation are possible; either harvesting files of data during periodic site visits or via unmanned vehicles, or via real-time streaming to a topside modem permanently installed on nearby infrastructure.

Summary

France Energies Marines, in partnership with Cadden, deployed an Origin 600 ADCP in the Bay of Douarnenez, France. The Origin was configured to continuously measure currents and waves over a three‑day period in July 2024. Average current and directional and non-directional wave parameters were computed onboard the device using Sonardyne’s Edge computing environment. The results were reported every 20 minutes to a log file and streamed acoustically on the same cadence. This demonstrates the ADCP’s ability to accurately measure critical current parameters and report them wirelessly, taking advantage of the Origin’s key USPs of an integrated acoustic modem and onboard Edge processing.

Origin 600 can provide key optimisations in efficiency as site operators can access critical data when it matters. This capability can lead to substantial cost savings, such as fewer wasted crew mobilisations, early warning of infrastructure degradation, and more.