Taking to the Skies

THURN Group is a UK-based manufacturer that specializes in technology development, integration, and the sales and service of highly engineered systems for the seabed and inland waterway survey industries.

Since 2011, THURN has partnered with a long list of clients from the ocean industries, including offshore operators, survey services providers, and survey equipment manufacturers. As marine survey continues to explore the potential of increasingly remote operations, much of our work in recent years has centered around the integration of ever more advanced robotics as turnkey survey solutions, be them deployed on the water’s surface or in the air.

LIFT OFF

In early 2021, THURN Group launched the THURN QuickDip™ system for unmanned aerial vehicles (UAVs). This cutting-edge new system for autonomous airborne hydrographic survey can be supplied with a variety of in-water sensors and offers a range of benefits, which include rapid deployment and data collection from multiple sites of interest; autonomous, repeatable map-based surveys to monitor change detection; and the ability to safely collect data from difficult-to-access and dangerous waters, as well as restricted-access waters, such as reservoirs.

THURN’s integration with SPH Engineering’s UgCS hardware and software allows the drone to fly at an accurate fixed height over water using a map-based pre-programmed autonomous survey pattern, dipping the sensor into the water at known points and along pre-programmed paths and depths while taking continuous readings.

The drone-carried system is ideal for dangerous, inaccessible or very shallow waters, or where multiple quick missions are required in a short time over a wider area (for example sewage outflow lagoon systems). Risk is reduced as the launch and recovery of boats (manned or unmanned) in unfamiliar and unprepared settings carries much greater risk than a controlled UAV launch far from the water.

INDUSTRY COLLABORATION

The QuickDip system was first launched in partnership with leading oceanographic and hydrographic instrument manufacturer Valeport. Integration with Valeport’s miniSV&P (sound velocity and pressure) sensors enabled sond velocity profiles for correcting sonar depths. The THURN QuickDip+Valeport is now available with the Environmental range of sensors, including the Hyperion range of environmental sensors for the measurement of Turbidity, Chlorophyll a, Fluorescein, Rhodamine or Phycocyanin as well as the miniSVS, miniCTD, and SWiFT SVP.

The latest addition to the range is the THURN QuickDip™+side-scan. This is a dipping side scan sonar system which can be manually flown or fly an autonomous pre-programmed search pattern. The side scan is a selectable 330kHz/800kHz digital search and recovery sonar that sends out a pulse of sound to either side and receives the sound that echoes back off the seabed. As the drone tows the side-scan along, this enables riverbed imaging either side of the flight track. In other words, operators are able to render images of any submerged objects on a wide swathe of the seabed along the survey route. The width of the image depends on the useful range of the sonar, which depends on the sonar frequency and water environment.

IMPRESSIVE RESULTS

Testing on rivers in the UK has proven the system to be highly successful and gave ranges of approximately 25 m/side on the low frequency and at least 15 m/side on the high frequency (higher frequency produces higher resolution).

UAV flight time with the side scan is around 15-30 minutes, a window that mostly depends on the wind conditions. At a survey speed of about 2-4 kts (1-2 m/s), this allows about 1.5-2 km of survey line per set of batteries with an area coverage of around 100,000 square meters.

THE FUTURE

Now that the THURN QuickDip™ capability is available commercially, there are a whole range of sensors on the roadmap to be considered and integrated, from chemical to sonar to laser to radar, and even a sample-at-depth and quick-freeze system for environmental DNA lab analysis.

No question, 2021 is going to be an interesting year. THURN is reaching out to sonar and sensor manufacturers for solutions that address the challenges of surveying hard-to navigate nearshore waters, rivers or lakes. If manufacturers are interested in seeing their sensors integrated into a pioneering airborne or surface autonomous system, then they should get in touch with the New Product Development team at THURN Group Acle.

For more information, contact support@thurngroup.com or visit www.thurngroup.com.

This story was featured in ON&T March 2021. Click here to read more.