Dynamic cable monitoring using Distributed Fiber Optic Sensing

Acoustic Sensing (DAS) and Distributed Strain Sensing (DSS) offer spatially continuous measurements that can capture vibration, deformation and cyclic loading, but their interpretation remains challenging due to submarine ambient noise and complex strain transfer mechanisms.

Within the HT-20MW project funded by ADEME, CORIMER and France 2030, an 80 m dynamic cable was deployed offshore in a lazy-wave configuration to assess the capability of

DAS and DSS to monitor its dynamic behaviour under realistic operating conditions.

Fibre-optic signals were continuously recorded and compared with the motion of a floating structure equipped with an Inertial Navigation System (INS). The objective was not to reconstruct the full cable shape, but to analyse the response of DFOS measurements to dynamic excitation and their sensitivity to cyclic loading.

Results show that DAS measurements are highly sensitive to dynamic events and correlate with floater motion, while DSS captures slower variations related to global loading. These observations highlight the complementarity of DAS and DSS and provide insight into their applicability and limitations for long-term monitoring of dynamic subsea cables.