Abstract
The concept of adding a harbour, consisting of two parallel projections to a wave-energy device was first brought to the attention of the wave-energy community at a Symposium in Trondheim, Norway, in June 1982. The proponents of the idea claim that the performance of the device is considerably improved by the addition of the harbour, thereby reducing costs. In this paper two theoretical techniques are described for predicting the performance of the harbour system. First, a relatively simple approximate method using the theory of long thin harbours is described. Secondly, numerical techniques used for rigid-body interaction with waves are adapted to cope with harbour systems with no restrictions on dimensions. It is shown that the simpler approach gives results that agree closely with numerical calculations over a wide range of configurations. Hydrodynamic theory is used to evaluate the performance of the device, assuming that it can absorb energy through a resistive damper. The results are encouraging, demonstrating that the addition of a harbour can be very beneficial and confirming that the concept is worthy of closer scrutiny.