The measurement of the wave climate plays a vital role in many stages of the development of Marine Renewable Energy (MRE). Wave climate measurements are for example needed for resource characterisation for identification of potential sites for commercial developments or for environmental monitoring of MRE sites. Wave measurement is also needed in the development of MRE converters, during testing phases at model scale in a controlled environment up to testing phases at full scale out at sea.
Non-intrusive instrumentation can provide several benefits compared to in-situ instruments. The fact that the instrumentation does not interfere with the wave field to be measured can be an advantage in laboratory experiments where it reduces unwanted disturbances, but also at sea where the instrument does not (or less) suffer from exposure to sea water corrosion, bio-fouling, wave load and damages from human activities.
The Marinet program dedicated a work package (WP4-Research to innovate and improve Infrastructures, technologies and techniques) to improve the facilities, operational techniques and instrumentation at European Infrastructures for Offshore Renewable Energy Research. Within this work package, a task (T4.1.2) was identified to develop innovative non-intrusive methods in order to characterize the water wave conditions, for model scale measurements and full scale. Its aim was to build operational instruments and to produce guidelines about their use in WEC studies.
This document presents and discusses some recent developments in a number of non-intrusive techniques for the measurement of water waves, with particular attention paid to the recent works done by some partner institutions of the Marinet program. Because the spatial and temporal scales required for the study of water wave dynamics are different out at sea from those needed at model scale, the techniques developed do differ. Late developments in non-intrusive techniques for ocean wave field measurement at sea are presented in a first section, while those concerning techniques used in laboratories are presented in a second section.