Glossary of Nautical and Sailing Terms and Abbreviations

Navigating the waters of nautical and sailing terminology can be as challenging as sailing through uncharted waters. This comprehensive glossary covers essential terms and abbreviations, providing a valuable resource for both seasoned sailors and landlubbers alike. The terms are organized alphabetically for easy reference.

A

• Aback: When a sail is aback, the wind fills it from the lee side, pushing it against the mast. This is often unintended and can hinder forward motion.
• Abaft: Refers to a location on the boat towards the stern, relative to another object or position.
• Abeam: A direction or position on a boat that is at right angles to its centerline. It’s often used to describe the location of an object or another vessel relative to the boat.
• Aft: Located at, in, or towards the stern of a boat. It is a directional term indicating the rear part of the vessel.
• A-hull: A method used by sailors to ride out a storm with no sails set and the helm lashed to leeward. It’s a technique for minimizing strain on the boat during severe weather.
• AIS (Automatic Identification System): A tracking system used on ships for identifying and locating vessels by electronically exchanging data with other nearby ships and AIS base stations.
• Amidships: The central part of a boat, both in terms of length and width. It refers to the area around the middle of the vessel.
• Apparent Wind: The wind experienced by an observer in motion, combining the true wind and the wind added by the observer’s own speed. It’s important for navigation and sail adjustment.
• ARPA (Automatic Radar Plotting Aid): A system that uses radar to track the position and movement of other vessels, assisting in collision avoidance.
• Astern: Refers to a position or direction behind a boat. It can also describe the action of moving the boat in reverse.
• Athwartships: A direction or position that is at right angles to the fore-and-aft line of the boat. It’s often used in describing the layout or movement across a vessel.
• Azimuth: The angular distance measured in a clockwise direction on the horizon, usually from a fixed reference point like north. It’s a key concept in navigation for determining directions.
• Above Board: Referring to actions or behaviors that are honest, open, and not deceitful. It’s often used to describe dealings or transactions that are legitimate.
• Abandon Ship: A directive given to leave the vessel immediately, usually in the face of imminent danger. It’s a last-resort order when the ship is no longer safe.
• Aboard: Being on or within a vessel. The term “close aboard” implies proximity to another ship.
• Accommodation Ladder: A portable flight of steps down a ship’s side, used for boarding or disembarking.
• Admiral: A senior naval officer of flag rank, with different levels including Rear Admiral, Vice Admiral, and Admiral. This term has historical roots and is key in naval hierarchies.
• Admiralty Law: A body of law that governs maritime questions and offenses. In the UK, it’s administered by a specific division of the High Court.
• Adrift: Describes a vessel or object that is not moored, anchored, or otherwise fastened, floating freely. It implies a lack of control and can also refer to misplaced gear.
• Aground: A state in which a boat or ship is resting on the seabed or ground, often unintentionally. This can occur due to low tide or navigational errors.
• Ahead: A direction in front of the bow of the boat. Moving ahead means moving forward.
• Ahoy: A traditional cry to draw attention, often used in hailing a boat or ship. It’s a part of classic maritime communication.
• Aid to Navigation (ATON): Devices external to a vessel that assist navigators in determining their position or course, or in identifying dangers or obstructions. These include buoys, lighthouses, and markers.
• All Hands: Referring to the entire crew of a ship, including both officers and enlisted personnel. It’s often used to summon the whole crew for important announcements or emergencies.
• Aloft: Above the main structure of the ship, usually referring to the area around the masts and rigging. It’s a term often used when referring to work or lookouts positioned high on the vessel.
• Alongside: Being next to or by the side of a ship or pier. It’s often used when a vessel is moored or in close proximity to another object.
• Anchorage: A designated area suitable for anchoring or where ships can anchor. It can refer to a specific part of a harbor or port.
• Anchor’s Aweigh: This term is used to indicate that the anchor is clear of the sea bottom and, therefore, the ship is no longer secured to its anchoring spot. It signifies readiness to set sail or change position.
• Anchor Ball: A black shape hoisted at the forepart of a ship to indicate that the vessel is anchored in a navigable area or fairway. It’s a visual signal for other vessels.
• Anchor Buoy: A small buoy connected to the anchor to mark its position when dropped on the sea floor. It helps in locating and retrieving the anchor.
• Anchor Chain or Cable: The heavy chain or cable that connects the anchor to the ship, allowing it to be secured to the seabed. It plays a critical role in the anchoring system.
• Anchor Detail: A group of crew members assigned to handle the ship’s anchoring equipment during anchoring or getting underway. They manage the deployment and retrieval of the anchor.
• Anchor Light: A white light displayed by a ship at anchor, to be seen by other vessels at night. Larger ships over 150 feet display two anchor lights.
• Anchor Watch: The duty of ensuring that the anchor is holding and the vessel is not drifting, especially important in rough weather and at night. Many modern vessels use GPS systems with anchor watch alarm capabilities.
• Armament: Refers to the weapons carried by a ship. Armaments are critical for defense and, historically, for offensive naval actions.
• Ashore: Describes being on the land as opposed to being on a ship. Often used when crew members leave a ship to go onto land.
• Astern: The direction toward the back or stern of a vessel. It can also refer to a vessel or object located behind another vessel.
• Asylum Harbor: A harbor that provides shelter from storms or rough weather. It’s a place of refuge for vessels.
• ASW (Anti-submarine Warfare): Activities and equipment focused on combating and defending against submarines. It’s a key aspect of naval warfare.
• Athwart, Athwartships: Positioned or located at right angles to the fore-and-aft line of a ship. This term is often used in describing the layout of the ship or when something is across the vessel’s centerline.
• ATON (Aid to Navigation): Refers to any device external to a vessel that assists in navigation, such as buoys, lighthouses, and beacons. These are critical for safe maritime navigation, providing direction and warning of hazards.
• Avast: A command to stop or cease what is being done immediately. It’s a traditional naval term used to halt an operation or activity on the ship quickly.
• Awash: Describes a condition where the deck or surface of the vessel is barely above water, with water washing over it. It can indicate a dangerous situation, especially in rough seas.
• Aweigh: When the anchor is lifted off the seabed and is no longer holding the ship in place. It signifies the start of a journey or a change in the ship’s position.
• Aye, Aye: A response indicating that an order has been received, understood, and will be carried out. It’s a common response to commands in naval and maritime operations.
• Azimuth Compass: An instrument used to determine the position of the sun in relation to magnetic north. It’s crucial for navigation, especially in celestial navigation.
• Azimuth Circle: A navigational instrument used for taking bearings of celestial objects, aiding in determining the ship’s position and course.

B

• Ballast: Ballast refers to material placed in the lower part of a boat or ship to provide stability and improve its handling and balance. It can be water, sand, or other heavy materials, adjusted according to the vessel’s needs to maintain an even keel and optimal performance.
• Batten: A thin, flexible strip inserted into the sail’s edge, providing stability and shape to the sail, especially in stronger winds.
• Beam: The widest part of a boat, crucial for stability. It’s a key measurement in determining a vessel’s capacity and handling characteristics.
• Berth: A sleeping compartment on a boat, or a designated space in a harbor where a vessel can be moored.
• Bilge: The lowest part of a boat’s interior, where water typically collects and needs to be pumped out to prevent damage.
• Bilge Pump: A mechanical or manual device used to remove water accumulated in the bilge, essential for maintaining vessel buoyancy and safety.
• Boom: A horizontal pole attached to the mast, used to extend and control the foot of a sail.
• Bow: The front or forward part of a boat, often characterized by a pointed shape for cutting through water.
• Bowsprit: A spar extending forward from a ship’s bow, used to support fore-sails and increase sail area.
• Bridge: The area on a ship where the command and navigation are conducted, equivalent to a control center on larger vessels.
• Buoy: A floating device used to mark specific points in the water, like hazards, channels, or anchors.
• Bulkhead: A structural partition within a ship, dividing various compartments or sections for stability and safety.
• Back and Fill: A maneuver using the tide’s advantage when the wind is not favorable, typically in narrow channels or during docking.
• Backstays: Cables or lines extending from the ship’s stern to the masthead, providing support and stability to the mast.
• Baggywrinkle: A soft covering, usually made from old rope, wrapped around rigging cables to prevent sail chafing.
• Bar: A large mass of sand or earth formed by sea surges, often found at river mouths or harbor entrances, affecting navigation.
• Barrelman: A sailor stationed in a crow’s nest, responsible for lookout duties and spotting hazards or other ships.
• Bar Pilot: A specialist navigator who guides ships through challenging areas like sandbars or river mouths.
• Beacon: A fixed navigation aid, either lighted or unlighted, attached to the earth’s surface, marking hazards or guiding paths.
• Bear Away/Down: Nautical terms for steering a vessel away from the wind, often during maneuvers or in response to wind shifts.
• Bearing: The direction or position of an object, typically another vessel, relative to one’s own position, measured in degrees.
• Before the Mast: A term referring to the living quarters of enlisted sailors, located in the front part of the ship.
• Belaying Pins: Rods or bars used to secure ropes or rigging on a ship, typically made of wood or metal.
• Best Bower: The larger of two anchors on a ship, often the primary anchor used for securing the vessel.
• Bimini: A protective covering, typically made of weather-resistant fabric, mounted over a boat’s cockpit to shield from sun or rain. It’s a common feature in sailboats and yachts for added comfort.
• Binnacle: A stand or housing on a ship that holds navigational instruments, including the ship’s compass. It’s essential for maintaining the ship’s course.
• Bitts: Strong vertical posts on a ship’s deck for fastening ropes or cables, especially important during mooring or towing operations.
• Bitter End: The final part of a rope or anchor cable. In nautical usage, reaching the ‘bitter end’ means using the entire length of the rope or cable.
• Boatswain (or Bosun): A non-commissioned officer on a ship responsible for maintaining the vessel’s rigging, sails, and other equipment.
• Boom Vang: A device used on sailboats to control the angle and bend of the boom, thereby influencing sail shape and performance.
• Bow-Chaser: A type of long gun placed at the front of a ship, used for firing directly ahead, especially useful in naval pursuits.
• Bowline: A type of knot creating a fixed loop at the end of a rope, known for its strength and stability.
• Bowsprit: A spar extending forward from a ship’s bow, used to increase the area for fore-sails and enhance sailing efficiency.
• Broaching-To: A sudden veering or turning of a ship, often causing it to face into the wind or waves, potentially dangerous in heavy seas.
• Bulwark: The extension of a ship’s sides above the level of the deck, providing protection against waves and adding structural integrity.

C

• Cabin: Enclosed living space on a boat, offering shelter and accommodations. It can range from basic to luxurious, depending on the vessel.
• Cable: A large rope or a measure of distance at sea, often used in anchoring or mooring a vessel. It is crucial in various maritime operations.
• Capsize: The act of a boat turning over in the water, which can be accidental or due to extreme conditions. Capsizing is a critical concern in boating safety.
• Chart Datum: A reference level on nautical charts, indicating the lowest tide level. It’s essential for safe navigation, especially near shorelines.
• Cleat: A fitting, often made of metal or plastic, used for securing ropes on a boat. It’s a fundamental piece of hardware for mooring and rigging.
• Cockpit: The area, usually lower than the deck, where the boat’s controls are located. It’s the primary operating station for steering and maneuvering.
• Companionway: The set of steps or a ladder leading from the boat’s deck down to the cabin. It serves as the main entry to the interior.
• Catamaran: A boat with two parallel hulls, offering stability and space. It’s popular for both recreational and racing purposes.
• Centreboard: A retractable keel that moves vertically, used to reduce sideways movement (leeway) in sailing boats.
• Clew: The lower aft corner of a sail, where the foot and leech intersect. It plays a crucial role in controlling sail shape.
• Close-Hauled: Sailing as close to the wind as possible without stalling. It’s a challenging point of sail requiring precise control.
• Cringle: A reinforced eyelet, often found at the ends of reef lines or on sails, used for securing or adjusting the sail.

D

• Daggerboard: A vertically movable fin in smaller sailboats, providing stability and controlling side-slippage.
• Deck: The top surface of a boat’s hull where crew and passengers stand.
• Deadrise: The angle formed between the boat’s bottom and a horizontal plane, is important for understanding hull design.
• Dinghy: A small boat, often used for short trips or as a tender for larger vessels.
• Dodger: A protective covering over the cockpit area, shielding from wind and spray.
• Davy Jones’ Locker: Nautical folklore for the seabed, symbolizing the final resting place of drowned sailors.
• Daybeacon: An unlit navigation marker, visible in daylight, used for identifying locations or hazards.
• Deadeye: A round wooden block with holes, part of a ship’s standing rigging, used for tensioning shrouds.
• Deckhand: A crew member responsible for general work on the main deck.
• Derrick: A lifting device on ships, composed of a mast or pole and a boom, used for cargo handling.
• Devil Seam: A particularly difficult seam to seal on a ship’s hull, located near the waterline.
• Dog Watch: A shorter than usual watch period on ships, typically two hours, to rotate duty times.
• Dolphin: A man-made marine structure of piled beams for mooring or navigational aids.
• Downhaul: A rope or line used for adjusting the tension on a sail or spar.
• Draft: The vertical distance from the waterline to the lowest point of a ship’s keel, important for determining navigable water depth.
• Dredging: The removal of sediments and debris from the bottom of water bodies to deepen them for navigation, environmental cleanup, or land reclamation.
• Drogue: A device trailed behind a boat to slow it down, particularly useful in heavy weather to control speed.

E

• EPIRB (Emergency Position Indicating Radio Beacon): A crucial safety device that sends out a distress signal in emergencies, helping in the location of vessels in distress.
• Engine: The power unit used to propel a boat, varying in type and size depending on the vessel.
• Earrings: Ropes used to secure the top corners of large sails to the yardarms, essential in sail management.
• Embayed: A situation where a vessel is trapped between headlands, often with winds blowing onshore, posing navigational challenges.
• Even Keel: Even keel refers to a condition where a boat or ship is perfectly balanced in the water, not tilting to either side. This balance is crucial for optimal performance and safety, ensuring the vessel moves efficiently and remains stable.
• Extremis: A critical point in navigation rules where vessels in danger of collision must take action to avoid it.
• EP (Estimated Position): A navigational term referring to the calculated location of a vessel based on estimations.
• ETA (Estimated Time of Arrival): The predicted time a vessel is expected to arrive at a destination. Read more: What Is ETA and ETD in Shipping?
• ETD (Estimated Time of Departure): The planned time for a vessel’s departure from a port or location. Read more: What Is ETA and ETD in Shipping?

F

• Fairlead: A fitting that guides ropes smoothly, preventing friction and wear.
• Fathom: A unit of depth measurement in maritime contexts, equal to six feet. Read more about fathom as a nautical measurement.
• Flare: An emergency signaling device emitting bright light, used for distress signaling at sea.
• Fender: A cushioning device, often air or foam-filled, used to prevent a boat from damaging itself or other objects.
• Figurehead: A decorative symbol located at the front of older sailing ships.
• Fireship: Historically, a ship filled with explosives and set on fire, used as a weapon.
• First Rate: A classification for large, heavily armed warships in the 17th to 19th centuries.
• Flag Hoist: A series of signal flags strung together to convey messages.
• Fluke: The wedge-shaped part of an anchor’s arm, essential for securing the anchor in the seabed.
• Forecastle: A section at the front of a ship, traditionally housing crew quarters.
• Furl: To roll or wrap a sail around a spar or mast, a common practice in managing sails.

G

• Galley: The kitchen area on a boat, equipped for cooking and preparing meals.
• Genoa: A large jib or foresail, often overlapping the mainsail, used for improved sailing efficiency, especially in lighter winds.
• Gimbal: A pivoting support allowing an object to remain level regardless of the boat’s motion, commonly used for compasses and cooking appliances.
• Gudgeon and Pintle: Components of the hinge mechanism connecting the rudder to the boat, crucial for steering.
• Gaff: A spar supporting the upper side of a fore-and-aft sail, essential in traditional sail configurations.
• Gangplank: A movable bridge allowing passengers and crew to board or leave a ship, especially at a pier.
• Garboard: The bottom plank of a boat’s hull, adjacent to the keel, playing a critical role in hull integrity.
• GPS (Global Positioning System): A satellite-based navigation system providing location and time information globally, vital for modern navigation.
• Grapeshot: A type of ammunition used in naval warfare, consisting of small metal balls, effective against personnel rather than structures.
• Gybe (or Jibe): A sailing maneuver where the boat turns so its stern passes through the wind, used to change direction.

H

• Hank: A fitting used to connect a sail’s luff to a stay.
• HAT (Highest Astronomical Tide): The highest level of tide predicted under average meteorological conditions.
• Hatch: An opening in a ship’s deck for interior access.
• Head-to-Wind: Position where a boat’s bow points directly into the wind.
• Headfoil: A streamlined cover around a forestay, with a groove for a headsail’s luff.
• Heads: Toilets on a boat.
• Headway: Forward movement of a boat through water.
• Heave-to: A maneuver in heavy weather to reduce a boat’s headway by backing the jib and lashing the tiller to leeward.
• Heel: The action of a boat leaning to one side.
• Halyard (or Halliard): Line used to hoist a sail’s head or a spar; essential for sail manipulation.
• Hammock: Canvas bed slung from a ship’s deckhead, used for sailors’ sleeping quarters.
• Hand Bomber: Historical term for a ship with manually shoveled coal-fired boilers.
• Hand over Fist: Expression describing steady upward climbing, akin to a sailor ascending a ship’s shrouds.
• Handsomely: Slow, steady motion, especially when hauling a line.
• Hank: Fastener attaching a sail’s luff to the forestay, typically featuring a spring-operated gate or snap fastener.
• Harbor (or Harbour, Haven): A natural or man-made shelter for ships, providing protection from weather.
• Haul Wind: Sailing towards the wind’s direction, not the fastest sailing point.
• Hawse-hole: A hole in the ship’s bow for anchor cables or chains.
• Hawsepiper: A maritime officer who started as an unlicensed seaman without formal maritime education.
• Head: The toilet or latrine on a vessel, traditionally positioned at the bow.
• Head of Navigation: The farthest navigable point on a river for ships.
• Headsail: Any sail flown in front of a vessel’s foremost mast.
• Heave: A vessel’s temporary vertical motion, up and down.
• Heaving to: Stopping a sailing vessel by opposing the helm and sails, causing a leeward drift.
• Heave Down: Tilting a ship on its side, often for cleaning purposes.
• Heeling: The leaning of a sailing vessel caused by wind pressure on its sails.
• Helmsman: Person responsible for steering a ship.
• Hogging (or Hog): Hull distortion where the keel’s ends are lower than the center.
• Hold: The lower part of a ship’s interior, used for storage, such as cargo.
• Holiday: An unintentional gap in the application of paint or other preservative substances.
• Holystone: Sandstone block used for scrubbing a ship’s deck.
• Horn: A sound signal device powered by electricity or compressed air.
• Horse: Attachment for sheets on a vessel’s deck.
• Hounds: Attachments for stays on masts.
• Hull: The shell and structural framework of a ship’s basic flotation section.
• Hydrofoil: A boat with underwater wings or foils for lift and speed enhancement. Read more about Hydrofoil boats

I

• Icebreaker: A ship designed to navigate and break through ice-covered waters, enabling travel in polar regions. Read more about how icebreakers work or the top 10 biggest icebreakers in the world.
• Icing: A hazardous condition where sea spray freezes upon contact with the ship in cold temperatures (below about -10°C) and high wind speeds (force 8 or above on the Beaufort scale).
• Idlers: Members of a ship’s crew who are not required to stand watches, typically specialist tradesmen like carpenters and sailmakers.
• IMO (International Maritime Organisation): A specialized agency of the United Nations responsible for regulating shipping.
• Impeller: A rotating component in a pump or engine, used to move water for cooling or propulsion.
• In Irons: A sailing term for when a boat’s bow is into the wind, causing it to stall and lose maneuverability.
• In the Offing: Originally meaning in the waters visible from onboard a ship, now refers to something imminent or about to happen.
• Inboard Motor: An engine mounted inside the boat, typically below the deck, used for propulsion.
• Inboard-Outboard Drive System: A hybrid marine propulsion system combining features of inboard and outboard motors, often found in larger powerboats.
• Inclinometer: An instrument used on ships to measure the degree of tilt or inclination, showing the vessel’s angle relative to the horizontal.
• IRPCS (International Regulations for Preventing Collisions at Sea): A set of international rules governing navigation to prevent collisions between vessels at sea.
• Isobars: Lines on a weather map joining places of equal atmospheric pressure, crucial for weather prediction and navigation.
• ITU (International Telecommunication Union): A United Nations specialized agency for information and communication technologies, including maritime communications.
• Jib: A triangular sail set forward of the mainmast of a boat, critical for maneuvering and speed.

J

• Jack: In nautical terms, it refers to either a flag, specifically flown at the jackstaff at the bow of a ship, or colloquially to a sailor.
• Jacklines or Jack Stays: Lines, often steel wire with a plastic coating, running from bow to stern on both sides of a ship, used for clipping on safety harnesses to secure crew while allowing deck mobility.
• Jack Tar: A term for a sailor, historically dressed in ‘square rig’ with a square collar and sometimes a tarred pigtail.
• Jib: A triangular staysail set at the front of a ship, important for its maneuvering and speed.
• Jibe (or Gybe): A sailing maneuver where the stern of the boat turns through the wind, changing the side of the boat the sail is on.
• Jigger-mast: The fourth or rearmost mast on a ship, generally the smallest on vessels with fewer than four masts.
• Jollies: A traditional Royal Navy nickname for the Royal Marines.
• Junk: Old, unusable cordage on a ship, often repurposed by teasing apart strands in a process called picking oakum.
• Jury: Refers to a temporary replacement for lost or damaged gear on a ship, often improvised in emergencies.

K

• Keel: The primary structural element of a boat’s hull, extending along the bottom and often protruding into the water for stability.
• Keelhauling: A severe maritime punishment involving dragging a person under the keel of a ship.
• Kedge: A small, light secondary anchor used for additional anchoring or maneuvering.
• Kelson (or Kelson): A timber placed immediately above the keel inside a wooden ship, contributing to the hull’s structural integrity.
• Ketch: A two-masted sailing vessel with a mainmast and a smaller mizzenmast, the latter stepped forward of the rudder post.
• Kicking Strap (or Boom Vang): A line or tackle used to control a sailboat’s boom position, pulling it down to maintain a horizontal orientation, especially useful on a reach or run.
• Killick: A small anchor, symbolically representing a non-commissioned officer in the Royal Navy, or used colloquially to refer to an able seaman skilled in anchor handling.
• Kissing the Gunner’s Daughter: A naval punishment where a sailor was bent over a cannon’s barrel for a spanking with a cane or cat-o’-nine-tails.
• Know the Ropes: A phrase indicating thorough familiarity with the ropes and cordage necessary for operating a ship.

L

• Ladder: On ships, most ‘stairs’ are called ladders, typically narrow and nearly vertical.
• Laker: A vessel that operates exclusively on the Great Lakes.
• Land Lubber: A person inexperienced or unfamiliar with the sea and sailing.
• Lanyard: A short line used to secure or tether an object, such as a tool, to prevent loss.
• Larboard: Archaic term for the left side of a ship, now known as ‘port’.
• Large (By and Large): Nautical term referring to sailing both with and against the wind.
• LAT (Lowest Astronomical Tide): The lowest level that sea tides can reach, used as a reference in charting.
• Lateral System: Navigation aids system indicating the sides of channels relative to a conventional direction.
• Lay: Orders related to crew movement or ship’s course; also, the twisting of rope strands.
• Lay Down: To begin ship construction in a shipyard.
• Lazy Jacks: Lines or ropes used to assist in controlling a sail when lowering or reefing.
• League: A unit of distance, often equated to three nautical miles.
• Lee: The side of the boat sheltered from the wind.
• Lee Helm: Tendency of a boat to bear away from the wind, requiring the helm to be pushed leeward to maintain a straight course.
• Lee Shore: A shore onto which the wind blows, posing a risk for ships being blown aground.
• Leech: The after edge of a sail, particularly susceptible to twist and controlled by the vang and mainsheet.
• Leeward: The direction toward which the wind is blowing.
• Leeway: The sideways movement of a ship off its course due to wind pressure.
• Let Go and Haul: An order indicating alignment with the wind.
• Letter of Marque and Reprisal: A government license authorizing a privateer to attack enemy ships.
• Lifeboat: A small, sturdy boat carried on ships, used for emergency evacuation.
• Lifeline: A safety line or cable running along the sides of a boat.
• Liferaft: An inflatable raft used for emergency abandonment of a ship.
• Line: The correct nautical term for ropes used on a vessel, each with a specific name based on its use.
• Liner: Originally a term for major warships in a battle line; now refers to large, prestigious passenger vessels.
• List: The lean or tilt of a vessel to one side due to uneven weight distribution.
• Loaded to the Gunwales: Having cargo loaded up to the ship’s rail; colloquially, being extremely drunk.
• Loggerhead: An iron tool for driving caulking into seams; historically, also used in fights.
• Lubber’s Line: A line inside a compass case indicating the ship’s heading.
• Luff: The forward edge of a sail; ‘to luff up’ means turning the boat’s head into the wind.
• Luffing: The condition when a sail is not fully filled with wind, often indicated by flapping.
• Lying Ahull: A storm tactic where all sails are doused and the boat is left to drift.

M

• Mainbrace: The brace attached to the mainmast.
• Mainmast (or Main): The tallest mast on a ship, supporting the primary sails.
• Mainsheet: A line used to control the angle and shape of the mainsail, affecting sail trim and boom position.
• Man of War: A warship from the age of sail.
• Man Overboard!: A cry indicating that a person has fallen off the ship.
• Marina: A facility for docking small ships and yachts, often with amenities.
• Marines Soldiers Afloat: Royal Marines with duties including guarding ship’s officers; formed in 1664.
• Marinized Engine: An automotive engine adapted for use in marine environments.
• Mast: A vertical pole on a ship supporting sails and rigging.
• Mast Step: The socket or base in the keel where the mast is fixed.
• Masthead: A platform partway up the mast, used for lookout and access to the main yard.
• Master: The commander of a commercial vessel or a senior naval officer responsible for seamanship and navigation.
• Master-at-Arms: A naval non-commissioned officer in charge of discipline.
• Matelot: A traditional Royal Navy term for an ordinary sailor.
• MCA (Maritime and Coastguard Agency): The organization responsible for maritime safety and regulation.
• Measured Mile: A nautical mile measured for testing a ship’s speed.
• Meridian: An imaginary line on Earth passing through the poles, used in navigation.
• Mess: An area on a ship where the crew eats; also, a group of crew members who eat together.
• Mess Deck Catering: A system where a mess group collectively manages and prepares meals.
• Midshipman: A junior officer in naval training.
• Mizzen: The shorter after-mast on a ketch or yawl; also, the sail on this mast.
• Mizzenmast (or Mizzen): The third mast on a ship, typically on larger vessels.
• Mizzen Staysail: A light sail set on a ketch or yawl, used in moderate conditions.
• MLWN (Mean Low Water Neaps): The average lowest tidal height at neap tides.
• MLWS (Mean Low Water Springs): The average lowest tidal height at spring tides.
• MHWN (Mean High Water Neaps): The average highest tidal height at neap tides.
• MHWS (Mean High Water Springs): The average highest tidal height at spring tides.
• MMSI (Maritime Mobile Service Identity): A unique identification number for maritime communications.
• Mooring: Securing a boat to a fixed point like a buoy or dock.
• Monkey Fist: A weighted ball woven from line, used for throwing a line to another location.
• Moor: To secure a boat to a mooring point or dock.

N

• Nautical Mile: A unit of distance in marine navigation, approximately equal to 1.852 kilometers.
• Navigation Rules: Guidelines, also known as “rules of the road,” for avoiding collisions at sea and determining responsibility in the event of a collision.
• Nipper: A short rope used to bind a cable to a moving line (messenger) during anchor operations, facilitating the cable’s movement.
• No Room to Swing a Cat: A phrase indicating a lack of space, historically referring to crowded conditions on a ship during floggings where there wasn’t enough room to swing the ‘cat o’ nine tails’ whip.

O

• Oilskin: Waterproof clothing worn by sailors in foul weather.
• Oar: A long pole with a flat blade, used manually for rowing a boat.
• Orlop Deck: The lowest deck in a ship, especially in ships of the line, often covering the hold.
• Orderbook: A record or list detailing the orders placed with shipyards for the construction of new ships. This term is commonly used in the maritime industry to gauge the level of activity and demand in the shipbuilding sector. Related article: What is a Ship Order Book? A Clear Explanation for Traders and Investors.
• Oreboat: A vessel, typically found on the Great Lakes, used primarily for transporting iron ore.
• Outboard Motor: A detachable engine mounted on the stern of a boat, used for propulsion.
• Overall Length (LOA): The total length of a boat or ship, measured from the foremost part of the bow to the aftermost part of the stern, excluding attachments like bowspritRelated article: What Do Boat Measurements Mean? 11 Terms Explained!.
• Outward Bound: Departing from a port or harbor, heading towards the open sea.
• Overbear: Sailing downwind directly at another ship to steal its wind.
• Overfall: Dangerous sea conditions with steep and breaking waves, often caused by opposing currents and winds in shallow areas.
• Overhaul: The action of hauling buntline ropes over sails to prevent chafing.
• Overhead: The ceiling on a boat, technically the underside of the deck above.
• Overreach: In sailing, maintaining a tack too long before changing direction.
• Over the Barrel: A phrase referring to the practice of flogging young sailors over a cannon’s barrel.
• Outhaul: A rope used to control the shape of a sail, particularly the foot.
• Overwhelmed: A term for a boat that has capsized or sunk.
• Owner: A traditional Royal Navy term for the captain, originating from the days of privately-owned ships in naval service.
• Ox-Eye: A cloud or weather phenomenon signaling the potential onset of a storm.

P

• Painter: The bow line used to tow or secure a dinghy or tender.
• Panpan: An urgency call over the radio, requesting assistance but not in immediate danger.
• Parrel: A movable loop securing the yard to the mast on a sailing vessel.
• Part Brass Rags: An expression meaning to fall out with a friend; originates from shared cleaning materials.
• Pay: The action of filling a seam with caulking or pitch, or lubricating rigging.
• Paymaster: A naval officer responsible for financial matters, including paying and provisioning the crew.
• Pier-head Jump: A last-minute assignment of a sailor to a warship just before its departure.
• Pilot: A navigator or person qualified to steer ships through challenging waters.
• Pilothouse: An enclosed space on a boat from where it is navigated and controlled.
• Pipe (Bos’n’s Call): A whistle used by boatswains to issue commands on a ship.
• Pipe Down: A signal indicating the end of the day, requiring silence and lights out.
• Piping the Side: A ceremonial salute using the bosun’s pipe to honor important individuals.
• Pitch: The up-and-down motion of a vessel’s bow and stern, rotating around its lateral axis.
• Pitchpole: To capsize a boat end over end, rather than by rolling.
• Pontoon: A flat-bottomed vessel, often used as a ferry, barge, or float for boarding.
• Poop Deck: A high deck on the aft of a ship’s superstructure.
• Pooped: Being swamped by a high, following sea, or colloquially, being exhausted.
• Port: The left-hand side of a ship when facing forward; marked with a red light at night.
• Port Tack: When a sailing boat has the wind coming from the port side and the mainsail is on the starboard side.
• Position Line/Line of Position: A line on a chart indicating a boat’s location, derived from bearings or sightings.
• Press Gang: Groups used historically by the Royal Navy to forcibly recruit men into naval service.
• Preventer (Gybe or Jibe Preventer): A line used to prevent or moderate accidental jibes.
• Privateer: A privately-owned vessel authorized to engage in warfare under a Letter of Marque.
• Propeller Walk (Prop Walk): The tendency of a propeller to push the stern sideways, affecting maneuverability.
• Prow: A poetic term for the bow of a ship.
• Pulley: A wheel on an axle designed to support movement and change of direction of a taut cable or belt.
• Pulpit: A metal guardrail at the bow of a boat, providing safety for the crew.
• Pushpit: A metal guardrail at the stern of a boat.
• Pusser: A naval term for the purser; responsible for supplies and provisions on a ship.

Q

• Quarter: The side of a boat between the stern and the beam, roughly midway along the boat’s length.
• Quarterdeck: Traditionally, the aftermost deck of a warship, reserved for the ship’s officers; often near the stern.
• Quay (or Quayside): A stone or metal platform lying alongside or projecting into water for loading and unloading ships.
• Queen’s (King’s) Regulations: The comprehensive orders governing the Royal Navy of the UK, issued under the authority of the reigning monarch.

R

• Radar: Acronym for RAdio Detection And Ranging, an electronic system used for detecting and locating objects using radio waves.
• Radar Reflector: A device that enhances a vessel’s visibility on radar screens by reflecting radar energy.
• Range: (1) In navigation, the alignment of two fixed points to guide a vessel; (2) the difference between high and low tide levels; (3) the distance at which a light is visible.
• Range Lights: Two lights aligned to form a navigational aid or mark a channel’s centerline.
• Ratlines: Rope ladders on a ship’s rigging to access masts and yards.
• Reach: A sailing point approximately 60° to 160° off the wind, including close, beam, and broad reaching.
• Reef: (1) To reduce a sail’s area in strong winds; (2) a rock or coral formation shallow enough to ground a vessel.
• Reef Points: Cords attached to a sail for securing excess fabric after reefing.
• Reef-Bands: Canvas strips sewn across sails for added strength.
• Reef-Tackles: Ropes used in the operation of reefing sails.
• Reefing Pennant: A strong line used to pull down the sail’s cringle to the boom during reefing.
• Reduced Cat: A lighter version of the cat o’nine tails, used for disciplining boys.
• Red Duster: Traditional nickname for the Civil Red Ensign.
• Rigging: The system of ropes, cables, or chains supporting a ship’s masts and controlling sails. More about Rigging!
• Rigging Screw: A device used to adjust the tension of a ship’s standing rigging.
• Righting Couple: The force that restores a ship to equilibrium after a heel alters the relationship between the center of buoyancy and gravity.
• Rigol: A rim or ‘eyebrow’ above a porthole or scuttle.
• Roach: The curved part of a sail’s leech, extending beyond a straight line from head to clew.
• Roll: A vessel’s side-to-side motion, rotating about the fore-aft axis.
• Rolling Tackle: Pulleys used to secure the yard to the weather side of the mast in rough seas.
• The Ropes: Refers to the lines used in a ship’s rigging.
• Rope’s End: A short length of rope used as a tool for summary punishment.
• Rudder: A flat piece, usually wood or metal, used to steer a ship.
• Rummage Sale: The sale of damaged cargo, derived from French ‘arrimage’.
• Running Rigging: The movable rigging of a ship, including lines like sheets and halyards, used to control sails’ position and shape.

S

• Sagging: The condition of a ship when a wave trough is amidships, causing the middle part of the ship to bend downward.
• Sail-plan: A set of drawings showing various sail combinations recommended for different conditions.
• Sailing Certification: Official recognition of sailing competence by an established sailing educational body.
• Saltie: A Great Lakes term for a vessel that also sails in ocean waters.
• Sampson Post: A strong vertical post supporting a ship’s windlass and the heel of the bowsprit.
• SAR (Search and Rescue): Operations aimed at finding and helping vessels in distress.
• SART (Search and Rescue Transponder): A device used in search and rescue operations to locate vessels.
• Scandalize: To temporarily reduce the area of a sail without properly reefing it.
• Scantling: Scantling refers to the set of standard dimensions for parts of a structure or vessel, particularly in shipbuilding. It includes the dimensions for beams, planks, ribs, and other components, ensuring structural integrity and compliance with design specifications and safety standards.
• Scud: The lowest clouds, observed mostly in squally weather.
• Scudding: Being carried furiously along by a storm.
• Scuppers: Openings on the side rails that allow water to drain off the deck.
• Scuttle: A small opening in a ship’s deck or hull; to sink a vessel deliberately.
• Scuttlebutt: A barrel for drinking water on a ship; also refers to gossip among sailors.
• Sea Anchor: A device deployed in water to stabilize a vessel in heavy weather.
• Sea Chest: A valve on a ship’s hull for water intake for ballast purposes.
• Seacock: A valve that controls water intake or discharge through the hull.
• Seaman: A sailor or crew member, often referring to lower ranks.
• Seaworthy: The condition of being fit and safe for navigating at sea.
• Securitay: A procedure word indicating a safety-related communication.
• Seelonce: Request for radio silence during a distress incident.
• Self-Unloader: A Great Lakes term for a vessel equipped to unload its cargo without external equipment.
• Sennet Whip: A device used for summary punishment on ships.
• Shackle: A metal link with a removable pin, used in various shapes for securing items.
• Sheave: A wheel or roller in a block, over which a rope runs.
• Sheer: The upward curve of a ship’s lines along its length, viewed from the side. More about Sheers
• Sheet: A rope attached to the lower corner of a sail for controlling its setting.
• Ship: A large vessel, traditionally a three-masted vessel square-rigged on all masts.
• Ship’s Bell: Used for marking time and regulating the crew’s watches.
• Ship’s Company: The collective term for the crew of a ship.
• Shoal: Shallow water that presents a hazard to navigation.
• Shrouds: Part of the standing rigging, running from the mast to the sides of the ship for support.
• Sick Bay: The medical compartment on a ship.
• Siren: A sound signal device using electricity or compressed air.
• Skipper: The captain or master of a ship.
• Skysail: A very high sail, above the royals, carried by few ships.
• Skyscraper: A small, triangular sail set above the skysail, used in light winds.
• Sloop: A single-masted sailing boat with one mainsail and one headsail.
• Slop Chest: A store aboard a ship selling items like clothing and tobacco to the crew.
• Slush: Greasy substance from boiling or scraping fat in meat storage barrels, used for greasing rigging.
• Slush Fund: Money obtained from selling ‘slush’, used for the crew’s benefit.
• Small Bower (Anchor): The smaller of two anchors carried at the bow of a ship.
• Son of a Gun: Originally, children born aboard ship; now used to refer to a mischievous person.
• Sonar: Sound Navigation And Ranging; a device for detecting objects underwater.
• Spanker: A sail on the aft-most mast of certain ships, like schooners and barques.
• Spanker-Mast: The aft-most mast on vessels like schooners and barquentines.
• Spar: A general term for poles like masts and booms on a ship.
• Spindrift: Spray blown from wave crests by strong winds.
• Spinnaker: A large, balloon-like sail used for down

T

• Tack (noun): The lower forward corner of a sail.
• Tack (verb): A maneuver where the boat turns so the bow passes through an imaginary line, pointing into the wind.
• Tacking: Sailing close-hauled on alternate courses so that the wind shifts from one side of the boat to the other.
• Taking the Wind Out of His Sails: Sailing in a way that steals the wind from another ship.
• Tang: A metal fitting for attaching rigging to a mast or spar.
• Tally: The action of hauling aft the sheets towards the ship’s stern.
• Tailshaft: A metallic shaft connecting the propeller to the power engine, aiding in propulsion.
• Teazer: A rope used as a punitive device.
• Tender: A small boat used to ferry people and supplies from a yacht to shore.
• Three Sheets to the Wind: A term describing a drunken sailor; metaphorically, a ship drifting aimlessly.
• Tide: The rise and fall of the ocean’s surface due to gravitational forces, mainly from the moon.
• Timoneer: A steersman of a ship, especially during specific maneuvers.
• Toe the Line/Mark: To stand in line with toes aligned with a seam on the deck, used in naval parades.
• Togey: Another term for a rope used as a punitive device.
• Topgallant: The mast or sails above the topsails.
• Topmast: The second section of a mast above the deck, carrying the topsails.
• Topsail: The second sail up a mast, either square or fore-and-aft.
• Topsides: The part of a ship’s hull above the waterline; also refers to above-water hull.
• Touch and Go: A situation where the ship’s bottom grazes the seafloor but doesn’t become grounded.
• Towing: The process of pulling a vessel forward by lines.
• Track: (1) The course made good by a boat; (2) a fitting on the mast or boom for a sail’s slide; (3) a fitting for a traveller.
• TrackLink: A GPS tracking app for student logbooks in sailing education.
• Traffic Separation Scheme: Designated shipping corridors that separate incoming and outgoing vessels.
• Transom: The flat surface forming the stern of a boat. Read more: What Is a Transom on a Boat? A Beginner’s Guide
• Travellers: Fittings that slide on a rod or line, commonly used for the mainsheet.
• Trim: (1) Adjusting the sails; (2) adjusting the boat’s load for optimal fore-and-aft angle.
• Trimaran: A boat with a main hull and two smaller outrigger hulls.
• True Wind: The actual wind speed and direction experienced when stationary.
• Tiller: A lever attached to the rudder, used for steering.
• Topsail: A sail located above the lowermost sail of a mast, typically in square-rigged vessels.
• Turtling: A capsizing incident where a sailboat’s mast points straight down and the hull resembles a turtle shell.
• Turnbuckle: A device used to adjust the tension of a ship’s rigging.
• Topping Lift: A line used to support the boom of a sailboat when the sail is not raised.
• Tide: The periodic rise and fall of the ocean’s surface caused by gravitational forces.
• Toe Rail: A low strip around the edge of a boat’s deck for safety and structural integrity.

U

• Under the Weather: Serving a watch on the weather side of the ship, exposed to wind and spray, often leading to feeling ill.
• Under Way:
  • In a general sense, a vessel that is moving or navigating, not anchored, moored, or aground.
  • Specifically, a boat is underway when it is not fastened to the shore, at anchor, or aground.
• Underwater Hull (or Underwater Ship): The section of a vessel that is submerged in water, typically visible only when the vessel is in drydock.
• Upper-yardmen: Sailors selected for advanced training or development, often earmarked for higher office or specialized duties.
• Up Haul: A line used to raise equipment vertically, such as the spinnaker pole on a sailboat.

V

• V-berth: A bed or sleeping space located at the bow of a boat, typically in a V-shape.
• Vang (or Kicking Strap): A line or rigging used to control the angle of the sailboat’s boom relative to the wind.
• Veer:
  • (1) Describes a clockwise shift in the wind’s direction.
  • (2) To gradually and controlledly pay out an anchor cable or rope.
• VHF (Very High Frequency): A radio frequency range used for marine communication.
• VMG (Velocity Made Good): A measure of the speed at which a vessel is moving towards its destination, considering both its course and the current.
• Vanishing Angle: The critical angle of heel beyond which a vessel cannot right itself and risks capsizing.

W

• Wake: The trail of disturbed water left behind a boat as it moves through the water.
• Wales: Thick, strong planks running lengthwise along the lower part of a ship’s side.
• Watch: A designated period during which part of the crew is on duty, with changes marked by ship’s bell.
• Watercraft: General term for all types of water transport vessels, including ships, boats, and personal watercraft.
• Weather Deck: The deck of a ship that is exposed to the weather, usually the main or upper deck.
• Weather Gage: A favorable position relative to another vessel concerning the wind.
• Weather Helm: The tendency of a boat to turn into the wind, requiring the tiller to be pulled windward for straight-line sailing.
• Weather Side: The side of a ship that is exposed to the wind.
• Weatherly: Describes a ship that sails well into the wind with minimal leeway.
• Weigh Anchor: The action of lifting the anchor in preparation for sailing.
• Wells: Sections in the ship’s hold designated for pumps.
• Wheelhouse: The area of a ship where the steering wheel is located; often synonymous with pilothouse or bridge.
• Whisker Pole: A lightweight pole used to extend the clew of a headsail, especially when running downwind.
• White Horses: Waves with foam or spray on their tops, typically formed in strong winds.
• Wide Berth: Allowing ample space between two moored ships for maneuvering.
• WGS84 (World Geodetic Survey of 1984): The most common chart datum used in global positioning systems.
• Windage: The resistance of a boat to the wind, caused by parts like rigging, spars, and crew.
• Windbound: Being confined to a particular area due to contrary winds.
• Windlass: A mechanical device, often horizontal, used for hauling anchor chains or ropes, providing greater mechanical advantage than block and tackle.
• Winch: A mechanical device with a drum and handle, used to haul or adjust tension on ropes or cables, aiding in sail control.
• Windward: The direction from which the wind blows; opposite of leeward.
• Wavelength: The distance between successive crests of radio waves.
• Vang (or Kicking Strap): Rigging used to control the boom’s angle, affecting sail shape.

X

• X-Band: A frequency band used in radar systems, specifically in the 7.0 to 11.2 GHz range, often used in marine radars for navigation and collision avoidance.
• XTE (Cross Track Error): The perpendicular distance a vessel has deviated from its planned track or course between two waypoints. It is a key parameter in navigation to ensure a vessel follows its intended route.

Y

• Yard: A horizontal spar from which a square sail is suspended on a sailing ship.
• Yardarm: The outer extremities of a yard. Commonly referenced in phrases like “hanging from the yardarm” or “sun over the yardarm.”
• Yarr: A traditional acknowledgment of an order or agreement among sailors.
• Yaw: The motion of a vessel rotating about its vertical axis, causing the bow to swing from side to side.
• Yawl: A two-masted sailing vessel with the mizzen mast positioned aft of the rudder post.

Z

• Zincs: Sacrificial anodes typically made of zinc, mounted on a boat’s hull to prevent galvanic corrosion by corroding themselves instead of the more important metal parts of the boat.
• Zephyr: A gentle, light breeze; often used in nautical contexts to describe mild winds that are favorable for sailing.