Dolphin (structure)

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For other uses, see Dolphin (disambiguation).
Dolphin structures in Germany.

A dolphin is a man-made marine structure that extends above the water level and is not connected to shore.

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 ships (or the number of ships expected) are greater than the length of the berth/pier.[1]

Typical uses include extending a berth (a berthing dolphin) or providing a point to moor to (a mooring dolphin). Dolphins are also used to display regulatory information like speed limits etc., other information like advertising or directions and navigation information like a daybeacon as well as ranges and lighted aids to navigation.

Mooring dolphins can also be used to "cushion" ship impacts, somewhat similar to fenders.[2]

The structures 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 azobé wood, pressure treated pine wood poles, or steel or reinforced concrete beams, blocks or tubes. Smaller dolphins can have the piles drawn together with wire rope, but larger dolphins would typically be fixed using a reinforced concrete capping or a structural steel frame.

Access to a dolphin may be via a pedestrian bridge (mooring dolphins) but is usually by boat.

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