A series of model tests was conducted in a wave flume 5 ft wide, 4 ft deep, and 119 ft long using a linear scale of 1:61.4 to determine the stability of a proposed rubble-mound breakwater with cover layers composed of tetrapod armor units. The stability of the breakwater sections, as a function of wave height, was observed visually; and the heights of waves on the harborside of the test sections, generated by wave overtopping and wave energy that was transmitted through voids in the upper portion of the breakwaters, were measured by an electrical wave-gage and oscillograph assembly. (Author).