Characterizing Vessel-Cable Interaction and Seabed Events Using Distributed Acoustic Sensing (DAS) for Maritime Safety Applications

Abstract

This work presents recent progress under the subsea cable sensing research programme in employing DAS for vessel activity characterization and subsea event detection. The study focuses on field validation of DAS signal behaviour during controlled vessel operations, including anchor drops on the seabed and injector movements during the subsea cable removal process, within the nearshore section of a sensing cable. Anchor-drop experiments exhibited clear high-frequency components in the 25–35 Hz range during impact, consistent with excitation from anchor contact. During injector setup and movement, distinct spectral features were observed: ∼10 Hz associated with slow repositioning, ∼30–36 Hz linked to the Hydraulic Power Unit (HPU), ∼13 Hz corresponding to thruster blade-passing vibration. When the cable was in physical contact with the injector during operation, the 13 Hz component was observed, indicating the vibration transmission through the injector structure and cable contact. When the operational linkage was released, this component disappeared and the cable was no longer interacting with the injector, verifying that the vibration transmission occurs only during direct physical interaction. Additional high-frequency signals (>25 Hz) recorded outside the test area suggest seabed-impact activity unrelated to ship operations.