Crew Transfer Vessels (CTV) are essential for the maintenance of offshore wind turbines. Their high speed operation in waves can benefit from an innovative onboard wave radar, coupled with motion prediction.

Figure 1 Wave observations with new radar in range 0-250m

Predictions are done by combining measured wave profiles forward of the ship with wave propagation and ship motion calculation models. This requires multi-disciplinary cooperation and expertise regarding radar technology, wave systems, vessel motions, as well as data processing and systems engineering. In the Do-It JIP MARIN worked closely with partners Radac, Damen, KNRM and NextOcean to improve the workability and safety of fast CTV serving the offshore wind sector. The project was supported by the RVO (Netherlands Enterprise Agency).

A real-time, fast craft motion prediction tool and measurement of wave orbital velocities using Doppler radar were the key aspects considered. An innovative, compact, solid state phased array FMCW radar was developed by Radac with the assistance of TNO; MARIN and NextOcean formulated a wave inversion model to integrate the Doppler orbital velocities into a 3D wave system and finally, MARIN developed and validated a numerical model for the fast boat motions. The complete system was integrated into a real-time simulation model and tested on board the Royal Netherlands Sea Rescue Institution (KNRM) lifeboats at speeds up to 30 knots.

The system will become available as an advanced onboard wave sensor and as an integrated motion prediction tool.

MARIN is continuing to assist Radac with the evolution of the technology. We are addressing the following:

  • The wave inversion algorithm for deterministic wave detection and forward prediction is being extended to provide validated wave statistics output.
  • Motion predictions and optimisation of the end user output will be addressed in the RVO-approved Offshore Operational Advisory System project, aka OOAS JIP, which is now starting.
  • Evaluation of the accuracy of the system in higher sea states where breakers and spray affect surface measurements.

MARIN intends to deploy the new wave radar in monitoring campaigns for ships, offshore structures and wind turbines in the very near future.