A vessel sunk deliberately to block a waterway to prevent the waterwayʹs use by an enemy.

Related Terms


Protected waterway suitable for vessel mooring.


The ratio of the underwater volume of a ship to the volume of a rectangular block with the same effective lengths, draft and beam


  1. Having freedom of motion interfered with by collision or entanglement; entangled; the opposite of clear. For instance, a rope is foul when it does not run straight or smoothly, and an anchor is foul when it is caught on an obstruction.
  2. A breach of racing rules.
  3. An area of water treacherous to navigation due to many shallow obstructions such as reefs, sandbars, or many rocks, etc.
  4. Foul the range: To block another vessel from firing her guns at a target.


All countries require that the importer make a declaration on incoming foreign goods. The importer then normally pays a duty on the imported merchandise. The importer's statement is compared against the carrier's vessel manifest to ensure that all foreign goods are properly declared.


A float or low, flat-bottomed vessel to float machinery such as cranes, capstans, etc. or to support weights such as floating bridges boat landings, etc.


A running light placed on the centerline of a vessel showing a continuous white light from dead astern to 67.5° to either side.


The location on a vessel a person goes either during an emergency or a drill to prepare for one. i.e. a Muster Drill. If a person is believed missing, all hands would report to their muster station for a head count.


  1. The underside of a vessel; the portion of a vessel that is always underwater.
  2. A cargo hold.


A system used by ships and Vessel traffic Service (VTS) principally for the Identification and the locating of vessels. AIS provides a means for ships to electronically exchange ship data including: Identification, position, course, and speed, with other nearby ships and VTS stations.


Cargo Control Room - the place where the loading or unloading of a tank vessel is controlled and monitored. Usually contains pump controls and vessel monitoring equipment.

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