Boat Terminology
Part III

Continuation of Boat Terminology Part II.


  • Halyard: The wire or rope used to hoist a sail.
  • Harden up: To alter course towards the wind.
  • Haze: A meteorological condition where the visibility is between 1000 and 2000 metres.
  • Heading: The direction in which the boat is pointing.
  • Headsail: A sail set forward of the mast.
  • Headway: Moving through the water in the direction the bow is pointing.
  • Heave-to: Is stopping the boat without lowering the sails. In a motor cruiser it means stopping the engine at sea.
  • Height of tide: The vertical distance between the actual height of water and the level of Chart Datum.
  • Hoist: To raise an object such as a sail using a halyard.


  • IALA: International Association of Lighthouse Authorities.
  • IALA A: A system of buoyage used in all areas other than the USA and Pacific Rim.
  • IALA B: A system of buoyage used in the USA and Pacific Rim.
  • In irons: A condition where the boat has stopped making way with sails flapping and is head to wind.
  • Isobar: A line joining points of equal pressure on a meteorological chart.
  • Isophase: A light characteristic consisting of equal lengths of light and darkness.


  • Jib: A triangular headsail set on the forestay.


  • Kedge anchor: A small anchor, often kept in a locker, for anchoring for a short time.
  • Ketch: A 2 masted yacht where the aft mast is forward of the rudder post.
  • Kicking strap: A device for pulling the boom down in order to flatten the mainsail.


  • Leach: The after edge of a sail.
  • Lee: The direction downwind.
  • Leeward: The opposite side of a boat to that from which the wind is blowing.
  • Leeway: The angle, caused by the wind, between heading and water track.
  • LOA: Maximum length of the vessel. The Length Overall.
  • Local time: The time you would see on a clock at the place specified.
  • Log: An instrument for measuring distance through water.
  • Luff: The front edge of a sail.
  • Luff: To alter course towards the direction of the wind.
  • LWL: The length of the vessel measured on the waterline.


  • Making way: A boat is 'making way' when it is moving through the water.
  • Mast - deck stepped: This means that the mast sits on top of the coachroof.
  • Mast - keel stepped: This means that the mast passes through the coachroof and sits on the keel.
  • Masthead rig: The forestay is attached to the top of the mast.
  • MHWN: Mean High Water Neaps.
  • MHWS: Mean High Water Springs.
  • Mizzen mast: The aftermost mast in a yawl or ketch.
  • MLWN: Mean Low Water Neaps.
  • MLWS: Mean Low Water Springs.

Go back to Boat Terminology Part II

Go further to Boat Terminology Part IV

Return from Boat Terminology to Boating Skills and Seamanship

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