CDR International BV is involved with the development of the new Crablock concrete armour unit as alternative to the existing artificial armouring of breakwaters and sea defences. The Crablock unit has the advantage of placement being performed with uniform orientation of the units. This reduces uncertainties in construction and hence increases safety, furthermore it provides 3 contact points with neighbouring units which increases the stability significantly. Currently several studies are being performed in collaboration with UNESCO-IHE from Delft (Netherlands) and Delft University of Technology to determine the actual stability of the unit, applicability finally optimize the unit. Based on this, first design guidance documents will be written.