Supported by Vattenfall and Geosea, W3G Marine recently achieved an underwater noise reduction of 25dB in SEL (Sound Exposure Level) and 35dB in peak pressure using its patented HydroNAS™ system.

The trial was conducted during the installation of a 5m diameter monopile with no energy restriction, using an S1200 hammer.

The result confirms numerical modelling conducted by the Institute of Sound and Vibration Research (ISVR) at Southampton University and follows three other successful scale trials and four years of development work.

The trial was configured to measure the transmission loss through the walls of the HydroNAS™ barrier and did not consider aspects of seabed noise transmission.

According to the company, HydroNAS™ represents a cost effective solution for piling noise mitigation which is installed off the main vessel critical path and requires minimal deck space.