Definition of Binnacle

The word “binnacle” comes from the Latin word “habitaculum”, meaning “little house”, and aptly refers to the non-magnetic, cylindrical structure on a ship that houses the delicate magnetic steering compass.

It’s typically made from brass or other non-ferrous materials and is usually located on the monkey island (topmost deck on the ship) and covered by a tarpaulin.

modern compass and binnacle in a sailboat

A magnetic compass is an essential part of a ship’s navigation. Unfortunately, the magnets in a compass respond to both the Earth’s magnetic field and the local magnetic field created by the iron parts of the ship.

The binnacle holds the compass steady and contains magnet correctors to adjust any deviations in the compass caused by the local magnetic field in the ship.

The key parts of a binnacle include:

  • Flinders bar: Contains iron bars of varying sizes to counteract the vertical magnetism occurring naturally in the ship
  • Quadrantal spheres: Are two movable spheres mounted on grooves on either side of the binnacle to adjust the compass deviation caused by iron material in the ship
  • Heeling magnet: Bucket and chain arrangement that corrects the compass deviation caused by the ship heeling or listing
  • Longitudinal and athwartship correctors: Correct deviation caused by the ship’s permanent magnetic field; positioned in both fore and aft, and at right angles to the centerline of the boat, respectively
  • Binnacle light: Illuminates the compass from below and has a dimmer switch to control the brightness, quite similar to the 120V Rotary Dimmer by Vimar
  • Gimbal arrangement: Allows the compass to move with the movement of the ship on the sea and still take steady bearings

a demonstration of the parts of a binnacle

Fun Fact: The word “binnacle” also refers to the part of a car’s dashboard that houses the speedometer and other gauges.

Example of Binnacle in a Sentence

"As the research of magnetism progressed, binnacles were constructed with greater attention to avoid compass disturbances caused by iron."

Related Terms for Binnacle