Editing Breakwater (structure) (section)

=== Rubble ===
Rubble mound breakwaters use structural voids to dissipate the wave energy. Rubble mound breakwaters consist of piles of stones more or less sorted according to their unit weight: smaller stones for the core and larger stones as an armour layer protecting the core from wave attack. Rock or concrete armour units on the outside of the structure absorb most of the energy, while gravels or sands prevent the wave energy's continuing through the breakwater core. The slopes of the revetment are typically between 1:1 and 1:2, depending upon the materials used. In shallow water, revetment breakwaters are usually relatively inexpensive. As water depth increases, the material requirements—and hence costs—increase significantly.<ref>{{Cite journal|last=CIRIA, CUR, CETMEF|date=2007|title=Rock Manual – The use of rock in hydraulic engineering|url=http://rockmanual.dicea.nl|journal=Ciria-CUR}}</ref>