Abstract: This paper presents the results from an experimental study on the power capture of bottompivoted pitching cylinders in intermediate water depth subjected to irregular waves. It follows the work presented by the same authors at the ICOE 2008, where the influence of damping and inertia modification was shown to be highly influential on power captured. Results of the experiments also showed that efficiency would benefit from having these parameters adjustable in response to the wave conditions.
The purpose of the work presented in this paper is to optimize the power capture of different cylindrical shapes by the mean of inertia modification, which could be implemented by allowing some compartment of the device to be filled by water.
A second aspect of this work is to assess the influence of the extent to which the device is surface piercing on its efficiency, as this design aspect could be critical for good public acceptance of future wave energy devices. From the results of the experiments in irregular waves, a full scale cylinder-shaped prototype of 6m diameter located in 25m water depth could absorb approximately 175 kW (average) in nominal winter conditions (based on observations from the North Atlantic) and approximately 40 kW (average) in summer sea states.
