Physical modelling of the SeAbacus wave energy converter

The SeAbacus is a new patent for a floating offshore wave attenuator, which essentially consists of a rafted Salter's Duck. It is modular, suitable also for low-energy seas and for array installation. This paper presents the first physical model tests carried out in the wave tank at the Hydraulic Laboratory of the University of Bologna. The tests focused on the effects of the device shape (by changing the shape of the Salter's Duck) and of the mooring layout (by testing a Tension Leg Platform, a Catenary Anchor Leg Mooring configuration and a spread mooring system) under wave attacks characterised by different wave height, wave steepness and wave obliquity. The results of the tests highlight the relevance of the shape of the Salter's Duck and the capability of the device of producing wave energy also in mild seas, provided a moderate wave steepness. Wave obliquity significantly decreases the device pitch motion. The mooring layout affects the device motions because the more rigid the moorings the higher the device pitch due to combined motions of the raft and of the Salter's Duck. The best compromise between device pitch motions and mooring loads was achieved with the spread mooring system.