Performance of a new submersible tide-wave recorder

This paper considers the comparative performance of a new pressure sensor wave recorder with that of two acoustic wave recorders. This new recorder is small (265 mm times 38 mm OD), and can be mounted on the sea or harbour floor, fastened to an existing structure, or attached to a mooring line. Recorders of this new type have been deployed in an open bay alongside both Nortek AWAC and RD Instruments ADCP acoustic instruments. The output of interest of any wave recorder is the significant wave height. It was demonstrated that as the sea-state became rougher, the new recorder correlated well with both acoustic systems. For calmer seas, the new recorder showed some discrepancies with the AWAC system, however, the AWAC was able to detect much higher wave frequencies during these episodes. This is a consequence of the deployment depth and the different measuring techniques of the AWAC system and the pressure-based recorder which is disadvantaged because the pressure signal of higher frequency waves experiences rapid attenuation with depth. These deployments demonstrated that the new recorder is a viable low cost method of measuring tide and sea-state in moored applications provided care is taken with the mooring details. To optimize the deployment, a new method for computing attenuation and other parameters is presented