In the present study the hydrodynamic interaction of regular and irregular waves with floating breakwaters (FBs) in shallow and intermediate waters
is examined experimentally in a large-scale facility. The experiments were conducted in the CIEM flume of the Catalonia University of Technology,
Barcelona. The influence of incident wave characteristics and certain geometric characteristics, such as the width and the draught of the structure,
on its efficiency is examined. Four different FBs configurations are examined: (a) single fixed FB, (b) heave motion FB, (c) single fixed FB with
attached front plate (impermeable and permeable) and (d) double fixed FB. Results related to transmission, reflection, and energy dissipation of the
incident (regular and irregular) waves on the structure are presented. For the single fixed FB, the efficiency of the structure is proportional to the
width/wavelength and draught/water depth ratios. The single fixed FB operates in a highly reflective manner. On the other hand, the heave motion FB
operates in a dissipative manner with much lower reflection. The attached plate in the front part of the FB significantly enhances the efficiency of the
structure. No significant differences are observed between the impermeable and the permeable plate cases. Generally, the most efficient configuration
has been the double fixed FB. However, with regard to cost-effectiveness, the configuration of the FB with the attached plate should be considered the
most efficient for design purposes.