Advancing submarine cable detection with inertial navigation technology

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In the subsea industry precision is paramount. Seekable BV, an emerging company in the Dutch geophysics market, aims to revolutionize submarine cable detection. Through a recent collaboration with Exail, they are integrating the Quadrans AHRS into their cable tracker prototype.

Seekable BV’s unique approach to cable detection

In the context of growth in the submarine cable systems market, Seekable BV, established since 2021, recognized the pressing need for precise cable localization. The alarming fact that 77% of financial losses in offshore wind projects are due to subsea cable failures emphasized the critical nature of their mission. Yet, the inherent challenges of fishing activities, anchoring mishaps, the lack of accurate data on cable positioning and burial depths represent significant obstacles.

Seekable BV’s innovative approach led to the development of a survey system capable of measuring electromagnetic fields emitted by subsea cables. This system accurately determines cable positioning and burial depths, addressing industry needs effectively. “Our system measures the magnetic field emitted by power cables and inverts this field to find the cable position under the seabed. We model the complex behavior of cables carrying currents, and our tailored algorithms ensures high precision for every type of cable.” comments Michiel Künzel, Geophysicist and Co-director at Seekable BV.

Seekable’s sensor cart setup. The Quadrans is mounted inside the black box at the center of the rig.

Achieving unprecedented accuracy with Quadrans AHRS

Seekable BV was looking for a robust motion sensor to convert cable positions into precise underwater coordinates. They chose Exail’s Quadrans AHRS for its renowned reliability and precision. Powered by fiber-optic gyroscope (FOG) technology, Quadrans surpasses traditional sensors, providing a high degree of precision as well as immunity to any electromagnetic interference. This system allows Seekable BV to achieve unrivaled accuracy and real-time cable detection.

Our original prototype faced severe issues with a MEMS-based magnetic heading sensor, greatly affected by the powerful electromagnetic fields around cables. Since switching to Exail’s Quadrans AHRS, our motion sensor values remain unaffected by cable EM noise. Our algorithms now function correctly, and the Quadrans offers superior precision compared to the MEMS sensor, enhancing both real-time performance and post-processing.” comments Michiel Künzel.

Quadrans is a fully strapdown gyrocompass and attitude reference system. Based on FOG technology, it provides all the necessary data for demanding navigation and control applications.

Showcasing precise cable localization through rigorous testing

Using Exail Quadrans, Seekable BV was able to carry out rigorous tests on various power cables, including those serving the Princess Amalia Wind Farm at Wijk aan Zee (Netherlands) and the BritNed cable connecting the UK and Dutch power grids. The Quadrans served as the center of gravity of their survey setup, surrounded by an H-frame containing five magnetometers to detect the cable’s EM field, and an RTK-GPS setup on top for positioning.

Survey cart (left, containing the survey computer) and sensor cart during a survey of the BritNed cable.

The results were impressive, showcasing high accuracy in estimating cable positions. Seekable BV’s confidence in its solution grew as the Quadrans AHRS consistently provided reliable data, paving the way for safer and more efficient cable maintenance. “The data gathered over the last few months has provided us with valuable insights into the behavior of electromagnetic fields around real-world cables. This has bolstered our confidence that our system will surpass currently available systems.” said Michiel Künzel.

Results of one of Seekable’s test surveys on an electrical cable landing. The estimated cable location is shown with bright colored dots, measured from two sensor cart traces (opaque dotted lines, 2-4 m distance). The real position of the cable is marked orange.

On the road to commercial deployment

Following successful initial testing, Seekable BV continues with sea trials and aims to enter the commercial market by Q4 2024.

Thanks to the data collected during the trial surveys, we are refining our algorithms and gearing up for our first marine trials. This milestone wouldn’t have been achievable without Exail’s support, and we extend our gratitude from everyone here at Seekable BV for the remarkable success achieved using their motion sensor.” said Michiel Künzel.

As Seekable BV transitions from testing to commercial deployment, its partnership with Exail illustrates the power of collaboration and innovation. “We are proud to collaborate with Seekable BV and excited to be part of their cable tacking solution by providing the necessary tools and support to turn their vision into reality. Seekable BV expertise and passion mirror Exail’s commitment for innovation, pushing technological boundaries beyond. This partnership underscores our belief that challenges can be overcome with ingenuity and that collaboration fosters solutions.” stated Theodora Sick, Regional Sales Manager at Exail.