Ship canals can be distinguished from barge canals, which intended to carry barges and other vessels specifically designed for river and/or canal navigation. Because of the constraints of accommodating vessels capable of navigating large bodies of open water, a ship canal typically offers deeper water and higher bridge clearances than a barge canal of similar vessel length and width constraints.
Ship canals may be specially constructed from the start to accommodate ships, or less frequently they may be enlarged barge canals or canalized or channelized rivers. There are no specific minimum dimensions for ship canals, with the size being largely dictated by the size of ships in use nearby at the time of construction or enlargement.
Ship canals may be constructed for a number of reasons, including:
- To create a shortcut and avoid lengthy detours.
- To create a navigable shipping link between two land-locked seas or lakes.
- To provide inland cities with a direct shipping link to the sea.
- To provide an economical alternative to other options.
Early canals were connected with natural rivers, either as short extensions or improvements to them.
In the modern era, canals in the United Kingdom are typically associated with the Duke of Bridgewater, who hired the engineer James Brindley and had the first canal (the Bridgewater Canal) built that ran over a flowing river.
In the United States, the canal that brought about an age of canal building was the Erie Canal. It was a long-sought-after canal and connected the Great Lakes to the Hudson River. This canal initiated a half-century-long boom of canal building and brought about many new features that allowed canals to be used in different areas previously inaccessible to canals. These features include locks, which allow a ship to move between different altitudes, and puddling, which waterproofed the canal.
Notable ship canals
The standard used in the European Union for classifying the navigability of inland waterways is the European Agreement on Main Inland Waterways of International Importance (AGN) of 1996, adopted by The Inland Transport Committee of the United Nations Economic Commission for Europe (ECE), which defines the following classes:
|Class||Tonnage (t)||Draught (m)||Length (m)||Width (m)||Air draught (m)||Description|
|Class IV||1,000–1,500||2.5||80–85||9.5||5.2–7.0||Johann Welker|
|Class Va||1,500–3,000||2.5–2.8||95–110||11.4||5.2–7.0–9.1||Large Rhine|
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