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A dolphin is a group of
Dolphins are also used to protect structures from possible impact by ships, in a similar fashion to fenders. A notable example of dolphins used to protect a bridge is the
A dolphin is a group of piling
A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site. A deep foundation is a type of foundation that transfers building loads to the earth farther down from th ...
s arrayed together to serve variously as a protective hardpoint along a dock, in a waterway, or along a shore; as a means or point of stabilization of a dock, bridge, or similar structure; as a mooring
A mooring is any permanent structure to which a seaborne vessel (such as a boat, ship, or amphibious aircraft) may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to ...
point; and as a base for navigational aid
A navigational aid (NAVAID), also known as aid to navigation (ATON), is any sort of signal, markers or guidance equipment which aids the traveler in navigation, usually nautical or aviation travel. Common types of such aids include lighthouses, ...
s.
Structure
Dolphins typically consist of a number of piles driven into the seabed or riverbed, and connected above the water level to provide a platform or fixing point. The piles can be untreated or pressure-treated timber piles, orsteel
Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...
or reinforced concrete
Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ...
piles. Smaller dolphins can have the piles drawn together with wire rope, but larger dolphins are typically fixed using a reinforced concrete
Reinforced concrete, also called ferroconcrete or ferro-concrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ...
capping or a structural steel frame.
Access to a dolphin may be via a pedestrian bridge, particularly in the case of mooring dolphins, but is often by boat.
Use
As mooring point
Dolphins are usually installed to provide a fixed structure when it would be impractical to extend the shore to provide a dry-access facility, for example, when the number of ships is greater than can be accommodated by the length of the berth/pier. Typical uses include extending a berth (a berthing dolphin) or providing amooring
A mooring is any permanent structure to which a seaborne vessel (such as a boat, ship, or amphibious aircraft) may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to ...
point (a mooring dolphin).
To protect structures
Dolphins are also used to protect structures from possible impact by ships, in a similar fashion to fenders. A notable example of dolphins used to protect a bridge is the Sunshine Skyway Bridge
The Sunshine Skyway Bridge, officially referred to as the Bob Graham Sunshine Skyway Bridge, is a pair of long beam bridges with a central tall cable-stayed bridge. It spans Lower Tampa Bay to connect Pinellas County (St. Petersburg, Florid ...
across the mouth of Tampa Bay
Tampa Bay is a large natural harbor and shallow estuary connected to the Gulf of Mexico on the west-central coast of Florida, comprising Hillsborough Bay, McKay Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay. The largest freshwater i ...
. In 1980, the MV ''Summit Venture'' hit a pier on one of the bridge's two spans causing a section of the bridge to fall into the water, resulting in 35 deaths. When a replacement span was designed, a top priority was to prevent ships from colliding with the new bridge. The new bridge is protected by 36 dolphins: four large dolphins protecting the two main pylons supporting the cable-stayed main span plus 32 smaller dolphins protecting bridge piers for to either side of the main span. The cost of the dolphins was $41 million (equivalent to $ million in dollars).
To support navigational aids
Dolphins are also used to house navigation aids such as lights or daybeacons, and display regulatory information such as speed limits and other safety information, or even advertising.See also
* Starling (structure) - a protective base for bridge piersReferences
{{DEFAULTSORT:Dolphin (Structure) Nonbuilding structures Nautical terminology