This paper reports on laboratory morphological studies of a shore-parallel porous breakwater system. A physical model study of the Elmer breakwater scheme, West Sussex, was conducted in the UK Coastal Research Facility (UKCRF) at HR Wallingford as part of an EPSRC-funded composite model evaluation (LUPY project). Mobile bed experiments, using both sand and anthracite as model sediments are described and discussed. Subsequent analysis showed that the evolution of equilibrium bays and their final width depend not only on the breakwater length and gap width, but also on the properties of the chosen model sediment and the permeability of the structure. It was also found that the 3D morphological changes influence the hydrodynamics, which in turn influences the evolution of the equilibrium morphological features.