About: Boom (navigational barrier)   Sponge Permalink

An Entity of Type : owl:Thing, within Data Space : 134.155.108.49:8890 associated with source dataset(s)

A boom generally floats on the surface, while a chain can be on the surface or below the water. A chain could be made to float with rafts, logs, ships or other wood, making the chain a boom as well. Especially in medieval times, the end of a chain could be attached to a chain tower or boom tower. This allowed safe raising or lowering of the chain, as they were often heavily fortified. By raising or lowering a chain or boom, access could be selectively granted rather than simply rendering the stretch of water completely inaccessible. The raising and lowering could be accomplished by a windlass mechanism or a capstan.

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rdfs:label
  • Boom (navigational barrier)
rdfs:comment
  • A boom generally floats on the surface, while a chain can be on the surface or below the water. A chain could be made to float with rafts, logs, ships or other wood, making the chain a boom as well. Especially in medieval times, the end of a chain could be attached to a chain tower or boom tower. This allowed safe raising or lowering of the chain, as they were often heavily fortified. By raising or lowering a chain or boom, access could be selectively granted rather than simply rendering the stretch of water completely inaccessible. The raising and lowering could be accomplished by a windlass mechanism or a capstan.
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dcterms:subject
dbkwik:military/pr...iPageUsesTemplate
abstract
  • A boom generally floats on the surface, while a chain can be on the surface or below the water. A chain could be made to float with rafts, logs, ships or other wood, making the chain a boom as well. Especially in medieval times, the end of a chain could be attached to a chain tower or boom tower. This allowed safe raising or lowering of the chain, as they were often heavily fortified. By raising or lowering a chain or boom, access could be selectively granted rather than simply rendering the stretch of water completely inaccessible. The raising and lowering could be accomplished by a windlass mechanism or a capstan. Booms or chains could be broken by a sufficiently large or heavy ship, and this occurred on many occasions, including the Siege of Damietta, the Raid on the Medway and the Battle of Vigo Bay. Frequently, however, attackers instead seized the defences and cut the chain or boom by more conventional methods. The boom at the siege of Londonderry, for example, was cut by sailors in a longboat. As a key portion of defences, booms were usually heavily defended. This involved shore-based chain towers, batteries or forts. In the Age of Sail, a boom protecting a harbour could have several ships defending it with their broadsides, discouraging assaults on the boom. On some occasions, multiple booms spanned a single stretch of water. File:Capturing Damiate.jpg|Dutch crusaders break a chain protecting the harbour (at left) in the Siege of Damietta. File:Boom Towers, Norwich - geograph.org.uk - 177643.jpg| Boom towers in Norwich File:Chain Bosphorus.JPG|Remains of the great chain that protected the Golden Horn File:The Great Chain Today.JPG|A preserved section of the Hudson River Chain
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