Background
Quay wall surveys are crucial for maintaining the safety and structural integrity in ports and harbors. This survey mission was completed by our German distributor, Subsea Europe Services with a 3,6m long MARTAC Systems Mantas T12 USV, fitted with a tilted Sonic 2026-V MBES.
Why USV?
USV’s are particularly well-suited for surveying in ports and harbors due to several key advantages that include their compact size and agility to navigate in tight spaces and reduced operational costs and emissions (the Mantas T12 operates with electric propulsion)
MBES System Description and Set Up
The Sonic 2026-V multibeam echosounder (MBES) is a shaped continuous wave system based on a sixth-generation sonar architecture that networks all modules and embeds the processor, controller and inertial measurement unit (IMU) in the sonar head to make for straightforward installation.
This all-in-one system minimises lever arm error and angular misalignment between the motion unit and the MBES, resulting in more accurate data collection. The high-resolution features of the 2026-V ensures a very detailed survey for vertical structures. The MBES was mounted on the USV using a tilted flange. The position and motion system is embedded in the MBES receiver and dual antennas were fixed 2,5m apart on the USV for high precision positioning, motion and heading. For the survey a tilt angle of 25 degrees was set, considering the depth of the flange and the space underneath the USV.
A survey grid of 15cm was used to create a detailed 3D model of the quay wall and environment. The multibeam depth was 0.60cm below the water surface and with the 25 degree tilt, the quay wall up to 0.9m below the water surface was achieved.
Outcome and Benefits
This survey successfully demonstrated the benefits of using a tilted MBES with a USV for vertical structure survey. The high resolution data collected by the Sonic 2026-V provided detailed and accurate representation of the quay wall, identifying any potential issues promptly. The use of the USV enhanced productivity and allowed for efficient data collection in tight and hard-to-reach areas.
Advantages of the tilted set-up over traditional beam steering methods for vertical structures:
- Optimized angle of incidence: With the tilted MBES, the beams are aligned more perpendicularly to the vertical surface, enhancing the quality and accuracy of the returned signal (reduces angle-related distortions)
- Enhanced surface detail
- Reduced complexity: No need for complex beam steering algorithms and operator interventions
- Improved coverage: Depending on the tilt, the wall close to the water line can be surveyed
- Minimized noise and artefacts improving the overall quality of the survey results
The only limitation of the tilted system is that survey lines can only be done in one direction with the tilted face on the vertical wall, and also the length of the flange and space under the USV will determine the tilt angle that you can achieve.
This case study illustrates the effectiveness and productivity that can be achieved by integrating one of the most advanced multibeam systems on an agile, high performing USV.
(Credit to Ezekiel David M.Sc., Ing. Jorge Ibaceta M.Sc and Subsea Europe Services for this case study information and photographs)
