Glossary of Nautical Terms

General Boating Terms

Term	Definition
Port	Facing forward, the left side of the boat. Indicated by a red light. Memory aid: "There's no red port left in the bottle" - 'Port' and 'left' both have 4 letters.
Starboard	Facing forward, the right side of the boat. Indicated by a green light. Memory aid: 'Right' and 'green' both have 5 letters.
Fender	The bumper you tie to the outside of your boat to prevent damage when docking.
Bearing	The relative angle between two objects.
Beam	The widest part of the boat.
Cleat	A T-shaped structure used to attach lines.
Davits	The hoist mechanism used to lift a dinghy out of the water.
Draft	The depth of a boat's keel below the waterline.
Cockpit	The outdoor seating area on a boat.
Foredeck	The forward exterior deck of a boat.
Bilge	The lowest part inside a boat or compartment.
Galley	The boat's kitchen.
Bridle	A line secured on both sides of the front of a catamaran to the anchor chain. Takes weight off the anchor winch and dampens noise.
Snubbing rope	A line secured at the front of a monohull, used to take the weight off the anchor winch and dampen noise.
Through Hull Valves	A valve permitting water to flow into the boat which can be closed off if needed, such as water cooling for an engine or a sink drain.
AIS	Automatic Identification System: a navigation system used for collision avoidance tracking and identification.
Aground	Resting on or striking the sea bed.
Awash	Water is just covering the surface of an object.
Ebb / Flood (tides)	Ebb: Tidal water moving out. Flood: tidal water moving in.
Shoal	Shallow water.
Slack tide	The period between the incoming and outgoing tides, when there is little to no water movement.
Lee shore	The shore downwind of a boat.
EPIRB	Emergency Position Indicating Radio Beacon - distress beacon.

Sailing Terms

Term	Definition
Lines	Another name for ropes.
Boom Bag	A canvas bag running the length of the boom, to hold the mainsail when not in use.
Lazy jacks	Lines running from the mast to the boom bag used to guide the sail when dropping.
Topping Lift	The line holding the back of the boom.
Halyard	The line that raises or lowers the sail.
Sheet	The line that controls sail position in and out, or side to side. Can refer to mainsail sheet or headsail sheet.
Main sail headboard	The top of the mainsail to which the halyard shackle and/or halyard pulley attaches.
Battens	Strips of plastic or fiberglass fitted into the mainsail, which help maintain the correct shape of the sail.
Furling Headsail	Where the sail rolls up around the forestay rather than being dropped on deck.
Unfurling	To unwrap the sail, letting it out.
Furling line	The line connected to the headsail furling drum, used to roll the sail in or out.
Furling drum	The mechanism located at the base of the forestay to which the furling line/rope rolls up on, to control the furling of the headsail.
Stay	A fixed line or cable running from the mast to the stern, side or bow of the ship to support the mast.
Forestay	A fixed line or cable from the front of the mast to the front of the boat, around which the roller-furling headsail is wound.
Traveller	A track fixed to the deck used to give additional adjustment to the headsail or mainsail sheets.
Mainsail Slides	The fitting that slides up or down the mast when hoisting or lowering the mainsail that holds the sail against the mast.
Tack / Tacking	To turn the bow of the boat into the wind to change course.
Gybe / Gybing	To turn the stern of the boat into the wind to change course.
Reef / Reefing	To reduce the area of a sail when hoisted or unrolled. Used in strong winds to prevent structural damage to the sail and rigging.
Spreader	Horizontal struts that brace the mast to the outer stays.
Apparent Wind	The strength and direction of the wind passing over the boat as a result of the combined effects of the true wind and the boat's speed.
Nautical Mile	A measurement of distance used on marine charts equivalent to 1.852 km or 1.1508 land miles, or one minute of latitude.
Knots	A unit of speed equal to one nautical mile per hour.