Use of minimal casting yard or barge space. Use of conventional construction materials and techniques. Existing unit shapes such as the dolos and tribar have slender central sections and long legs, producing very high stresses in the central sections of the units. This results in units which break into pieces having much less mass than the original unit. The broken units have little stability and may contribute to the breaking of adjacent units.
Tetrapods exhibit even lower stability than dolosse.
Their legs extend a shorter distance from the centroid so interlocking is less, and their rounded sections promote rocking on slopes and, when destabilized, rolling. In response to the shortcomings of these existing shapes, CERC developed Core-Loc. The Core-Loc shape has been optimized to provide maximum hydraulic stability, unreinforced strength, and reserve stability. The primary intent of this shape optimization is to have a very stable armor layer, with good wave energy dissipation characteristics, and yet have stresses low enough that normal-strength, unreinforced concrete can be used with little or no armor breakage occurring during the life of the structure. In addition to being used for new construction, the Core-Loc was designed to interlock well with dolosse for use as a repair unit.