pile breakwaters because of occupation of a small area is not harmful to sea wildlife. Construction of detached breakwaters There are two main types of offshore breakwater (also called detached breakwater): single and multiple. Single, as the name suggests, means the breakwater consists of one unbroken barrier, while multiple breakwaters (in numbers anywhere from two to twenty) are positioned with gaps in between (). The length of the gap is largely governed by the interacting wavelengths. Breakwaters may be either fixed or floating, and impermeable or permeable to allow sediment transfer shoreward of the structures, the choice depending on tidal range and water depth. They usually consist of large pieces of rock (granite) weighing up to 10–15 tonnes each, or rubble-mound. Their design is influenced by the angle of wave approach and other environmental parameters. Breakwater construction can be either parallel or perpendicular to the coast, depending on the shoreline requirements. Notable locations UK – The Sound, Plymouth; Sea Palling, Norfolk; Elmer, West Sussex; Brixham, Devon, South Gare United States – Long Beach, California; Santa Monica, California; Winthrop Beach, Massachusetts; Colonial Beach, Virginia Japan – Central Breakwater in Tokyo; Ishizaki (檜山石崎郵便局), Hokkaido Prefecture; Kaike, Tottori Prefecture India – Offshore Breakwater at Udangudi for captive coal jetty; Breakwater at BombaysMarine Drive. UAE - Dubai Palm Islands; Abu Dhabi Corniche Hong Kong – Kai Tak and Chep Lap Kok Airports Kuwait - Sabah Al Ahmad Sea City See also Seawall Mole (architecture) Groyne Phoenix breakwater Mulberry harbour Hudson's equation Powell River Giant Hulks breakwater Phoenix breakwaters Port References USACE (1984) – Shore protection manual (Volume I and II) N.W.H. Allsop (2002) – Breakwaters, coastal structures and coastlines. External links USGS Oblique Aerial Photography — Coastal Erosion from El-Niño Winter Storms October, 1997 & April, 1998 Channel Coastal Observatory — Breakwaters Gallery Shapes of breakwater armour units and year of their introduction SeaBull Marine, Inc. — Shoreline Erosion Reversal Systems WaveBrake – Wave attenuation specialists IAS Breakwater in Facebook Coastal engineering Coastal construction