Waves are primarily important for the tidal current power generation as they relate not only to the wave load acting on the tidal turbine but also to the installation/maintenance cost of the device through the workable day rate at the sea. Generally, the tidal current power site is in a narrow strait, and the wave characteristics are strongly dependent on the place. Also, there are few data itself. So, we conducted the wave observation in Naru Strait, Goto City, Nagasaki, where the tidal current power project by the Ministry of Environment is in progress.
An AWAC (Acoustic Wave and Current Meter) was deployed on the sea bottom of 20m depth in Naru Strait on 18 May and recovered on 12 November, 2017. The wave data obtained for about 6 months were analyzed as wave spectra and mean directions by the records of surface elevation together with tidal current velocity. In particular, the changes of wave amplitude by the tidal current and the storms including typhoon passing are presented.