Glossary of Nautical Terms

Since Sea Chest first set sail, and since we started writing our little sailor's blog, we've covered numerous topics and tutorials that every seafarer would enjoy perusing, from knowing how to Plot on a Nautical Map to understanding the growing world of Electronic Navigational Equipment.

One thing we've been quite remiss in is giving a comprehensive list of what all these ocean soaked and ancient terms even mean! So for today's entry, whether they help inspire affirmative action at sea or just a bit of fun banter, we've compiled a full Glossary of the most essential Nautical Terms for you to refer to - ideal for all your casual on-deck conversations!


Abandon Ship! - The phrase/command uttered in order to urge the crew to leave the ship in impending danger, usually as a last resort.

About - To change the course of the ship by tacking, phrased as "to go about".

Absolute bearing - The bearing of an object relative to either geographical or magnetic north.

Admiralty - A naval authority in command of not only a state's Navy, but also their territorial waters i.e. Admiralty law.

Adrift - A boat that is afloat and unattached in any way to the shore or seabed, but is not under way and usually not under control.

Aft - The portion of the vessel that lies behind the middle section of the ship.

Aground - The act of resting on or touching the bottom of a body of water, typically involuntarily.

Ahoy - A cry used to draw attention to an approaching ship, land or other object.

Aid to Navigation (ATON) - A term for any device that's external to the overall vessel that provides assistance to navigators in determining their positions, finding a safe course or to warn them of any oncoming dangers.

Anchor - A weighted object designed to prevent or slow the drift of a ship, usually with a shape designed to plough into the ottom of any body of water.

Apparent wind - A wind that's caused by a combination effect of the true wind, and headwind caused by the boat's own forward momentum.

Arc of Visibility - The portion of the horizon over which a lighted ATON is visible from seaward.

Avast - A command to stop, cease or desist from an activity on a vessel. Originates from a Dutch phrase of the same meaning.


Bareboat charter - Arranging the borrowing or hiring of a vessel, whereby no crew or provisions are included as part of the deal.

Beaching - The deliberate act of running a vessel aground to load, unload or prevent a damaged vessel from sinking.

Beacon - A fixed navigational aid attached directly to the Earth's surface, either lighted or unlighted.

Bearing - The horizontal direction of the line of sight between two objects positioned on the surface of the Earth.

Beating or Beat to - Sailing your vessel as close as possible towards the wind in a zig-zag course as a method of attaining upwind direction where it would be impossible to sail directly.

Berth - The safe distance to be kept between two or more vessels, or from an obstructing object.

Blue Peter - A blue and white flag hoisted on the fore trucks of ships ready to sail.

Bow thruster - A small propeller or water-jet at the bow, used for manoeuvring larger vessels at slow speed.

Broadside - One side of the vessel that is above the waterline.

Bulbous bow - A protruding bulb at the bow of a ship, just below the waterline, which modifies the way water flows around the hull and reduces drag.

Buoy - A floating object in the water that is anchored at a specific position in order to help sailors with navigation.


Cabin - An enclosed room on a boat's deck.

Caboose - A smaller ship's kitchen, or galley on deck.

Capsize - When any kind of vessel lists too far to one side and rolls over, exposing the keel. On large vessels, this is usually follows with the ship's sinking.

Careening - Tilting the ship on its side i.e. when beached to clear or repair the hull from below.

Catamaran - A sea vessel with two hulls.

Chine - A line formed where the sides of a boat meet the bottom.

Crow's nest - An alternative name for the masthead, particularly one with side and possibly a roof to shelter lookouts from the weather.


Debarcation - The process of leaving a ship, or removing goods from the vessel.

Decks - The top portion and structures forming the approximately horizontal structures of the boat.

Dinghy - A variety of small boat, often carried or towed by larger vessels.

Dock - Both the body of water between two piers and wharves to accommodate vessels, and the actual act of tying up your ship.

Dockyard - A facility where ships are built and repaired (different to a shipyard which is exclusively for the construction of ships).

Doldrums - A nautical term for the 'equatorial calms'; the quasi-continuous belt of low pressure lying between the subtropical high pressure belts of the Northern and Southern hemisphere.


Fairlead - A ring, hook or similar device used to keep a line or chain running the desired direction, and to prevent it from rubbing or fouling.

First mate - The second-in-command of a ship.

Flank speed - The maximum speed of a ship, normally used in imminent danger. It's actually faster than 'full' speed.

Freighter - A name for a cargo ship.


Galleon - A large, multi-decked sailing ship used within the European states between the 16th and 18th centuries.

Gunwale - The upper edge of a ship's hull.

Gybe - To change from one tack to the other in a direction away from the wind, with the stern of the vessel turning through the wind.


Harbour - A natural or man-made refuge for ships to shelter from the weather or be stored.

Haul - The phrase used for either steering a vessel closer to the direction of the wind, or for pulling the anchor from the bottom of the water.

Headsail - The sail that is flown in front of the most forward mast.

Heeling - The lean caused by the wind's force on the sails of a sailing vessel.

Helm - A ship's steering mechanism, typically the steering wheel,

Hogging - When the peak of the wave is amidships, causing the hull to bend and warp so the ends of the keel are lower than middle.

Hull - The shell or framework of the basic flotation-oriented part of the ship.


Jib - A triangular shaped staysail at the front of the ship.

Jury rig - Both the act of rigging a temporary mast or sail on a ship, and the name of the actual resulting rig.


Kedge - Both the name of a technique for moving or turning a ship using a light anchor, and the actual name of the anchor itself.

Keel - The central, structural basis of the hull

Knot - A unit of speed used by sea vessels, measured at 1 nautical mile (1.8520 km) per hour.


Land lubber - A slang word for someone unfamiliar with being on the sea.

Lateral system - A structured system of ATON's in which buoys and beacons indicate the sides of a channel or route relative to a conventional direction of buoyage.

Lay - To come and go and to direct the course of a vessel, used as a command to crews.

League - A unit of length, normally equivalent to three nautical miles.

Lofting - A technique of boat construction, where a scaled down drawing is converted to full size measurements.

Luff - The forwardmost edge of a sail.


Magnetic north - The direction towards the North Magnetic Pole, which varies very slowly over time depending on the Earth's surface.

Man overboard! - A phrase shouted out when a seaman has fallen from the ship into the water.

Marina - A docking facility for small ships and yachts.

Mast - A vertically standing pole on a sailing ship which supports sails or rigging.

Metacenter - The midway point between a vessel's centre of buoyancy when upright and her centre of buoyancy when titled.


Nautical mile - A unit of length used at sea that corresponds approximately to one minute of arc of latitude along any meridian arc. The international sailing community agrees it to be exactly 1852 meatres.


Pier - A raised structure in the water, which includes a bridge or some kind of walkway, supported underneath by widely spread pillars. used for multiple purposes, not least of which is the arrival of ships.

Pinnace - A small boat other than a launch or lifeboat that is associated with a larger vessel.

Piracy - An act of robbery or criminal violence at sea, committed by the crew or occupants of one vessel against another.

Pitch - The motion of a vessel that causes the fore and aft ends to rise and fall repetitively.

Points of sail - The general term for the course of a sailing vessel.

Poop Deck - A high deck on the aft superstructure of a ship.

Port - The left side of the boat, or the direction towards the left-hand side of the ship facing forward.


Quarterdeck - The aftermost deck of a warship. Formerly the name for the preserve of the ship's officers in the age of sail.

Quay - A stone or concrete structure on navigable water used for loading and unloading vessels a.k.a a wharf.


Radar - Radio Detection and Ranging; an electronic system that transmits and uses radio signals to determine the bearing and distance of a "target" that the waves reflect off of.

Reaching - Sailing across the wind.

Regatta - A series of competitive boat races.

Relative bearing - A bearing relative to the direction of the ship: the clockwise angle between the ship's direction and an object.

Rigging - The system of masts and lines on ships and other sailing vessels.

Rudder - A rudder is a device used to steer vessels by imparting a turning or yawing motion of the craft.


Sagging - When the trough of a wave is amidships, causing the hull to deflect so the ends of the keel are higher than the middle.

Scantlings - Dimensions of ship's frame, beam, girder, etc.

Sculling - On sailing boats this is a form forward propulsion  made by a balanced side to side movement of the tiller.

Seaman - A generic term for a sailor.

Sextant - A navigational instrument used to measure a ship's latitude by measuring the distance between two visible objects.

Shift tides - Calculating the relative effect of the tides on the navigation of the ship using a sextant and nautical almanac.

Shoal - Shallow water that can be hazardous to navigation.

SonarSound Navigation And Ranging; a method using sound pulses to detect, range and often to image underwater objects and obstacles on the bed of the sea.

Sounding - Measuring the depth of the water, today done with echo sounding.

Spindrift - Finely divided water swept from crest of waves by strong winds.

Starboard - The right side of the boat, or the direction towards the right-hand side of the ship facing forward.

Staysail - A fore-and-aft rigged sail whose luff can be affixed to a stay running forward

Stern - The rear part of a ship, technically defined as the area built up over the sternpost


Tonnage - Various measures of the size or cargo carrying capacity of a ship

True north - The direction of the geographical North Pole.


Upbound - The term for a vessel travelling upstream


Voyage - A long journey undertaken by a ship, and the verb for doing so.


Wake - The turbulence behind a vessel.

Wash - The waves created by a vessel; not to be confused with the wake.

Waterline - The line where the hull of a ship meets the water's surface.

Waterway - A navigable body of water.


Yacht - A recreational boat or ship

Yarr - The phrase to acknowledge an order, or a hearty phrase of agreement!

If there's any crucially important Nautical terms and phrases missing from this list that you know of, do pass them over to us by message in a bottle, or more easily through our Facebook page, on Twitter or via Google+!

Post By Graham