Discussion on papers 21 and 22

J. A. Melby, US Army Engineer Waterways Experiment Station

How did the authors monitor the placement of Accropode® units? In particular, did the authors utilize GPS or LVDT's on the crane, recently used in Spain to provide x, y, z coordinates for each unit? How did the authors maintain the specified packing density during construction and how close were they to the theoretical packing density?

E. Loewy, Consulting Engineer

Protection of 'intellectual property rights', e.g. by patent royalties, is essential for technological innovation in all fields including the construction industry. The high fees for use of Tetrapods in the 1960s stimulated a worldwide search for alternative designs. One of these, developed by Halcrow, was the 'Stabit' used successfully on the Port Qaboos main breakwater - now overtaken by designs such as Dolos and Accropode®.