flap gate

engineering
Also known as: box gate

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use in dry docks

  • Lorient
    In harbours and sea works: Entrances

    …the sliding caisson and the flap gate, or box gate, are perhaps the most popular. The sliding caisson is usually housed in a recess, or camber, at the side of the entrance and can be drawn aside or hauled across with winch and wire rope gear to open and close…

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shipyard, shore establishment for building and repairing ships. The shipbuilding facilities of the ancient and medieval worlds reached a culmination in the arsenal of Venice, a shipyard in which a high degree of organization produced an assembly-line technique, with a ship’s fittings added to the completed hull as it was floated past successive docks. In 18th-century British shipyards, the hull was towed to a floating stage called a sheer hulk, where it received its masts and rigging. Modern ships also are launched incomplete.

Typically, a shipyard has a limited number of building berths, sloping down toward the waterway, with large adjacent working areas. Plates and sections are delivered to a point distant from the berth and converge toward the berth as they are assembled into components and subassemblies, which are ultimately welded together. Very large ships are often built in deep drydocks because of the greater convenience in lowering large components. When the hull is complete, water is admitted and the ship floated to the fitting-out basin.

This article was most recently revised and updated by Amy Tikkanen.