Boating Basics Glossary of Nautical Terms
The world of boating has a pretty unique vernacular, and it’s important that you understand the differences between sailing words and land lubber words before you head out onto the water! Nothing highlights a newbie quite like the wrong use of a word!
You might know the difference between a bow vs stern, port or starboard, and can tell the difference between a bowline and a clove hitch, but if you don’t know what’s the opposite of aft or the opposite of windward, it’s time to brush up on your sailboat terms.
To make life easier, we’ve put together a concise glossary with every boat definition, nautical word, and ship terminology you could ever possibly need to know, with simple, easy to understand definitions, and links to more detailed sources when necessary.
If your boat lingo isn’t up to scratch, read on! Here’s all you need to know.
Boating Basics Glossary of Terms
ABAFT – Toward the rear (stern) of the boat. Behind.
ABEAM – At right angles to the keel of the boat, but not on the boat.
ABOARD – On or within the boat.
ABOVE DECK – On the deck (not over it – see ALOFT)
ABREAST – Side by side; by the side of. To define abreast in non sailing terms would be alongside something.
ADRIFT – Loose, not on moorings or towline.
AFT – Toward the stern of the boat. The aft of a ship is towards the rear of the ship, or the back of a boat.
AGROUND – Touching or fast to the bottom.
AHEAD – In a forward direction.
AIDS TO NAVIGATION – Artificial objects to supplement natural landmarks indicating safe and unsafe waters.
ALEE – A good alee definition would be: away from the direction of the wind. Opposite of windward.
ALOFT – Above the deck of the boat.
AMIDSHIPS – In or toward the center of the boat.
ANCHORAGE – A place suitable for dropping anchor in relation to the wind, seas and bottom.
ASTERN – In back of the boat, opposite of ahead.
ATHWARTSHIPS – At right angles to the centerline of the boat; rowboat seats are generally athwart ships.
AWEIGH – The position of anchor as it is raised clear of the bottom.
BATTEN DOWN – Secure hatches and loose objects both within the hull and on deck.
BEAM – The greatest width of the boat.
BEARING – The direction of an object expressed either as a true bearing as shown on the chart, or as a bearing relative to the heading of the boat.
BELOW – Beneath the deck.
BIGHT – The part of the rope or line, between the end and the standing part, on which a knot is formed.
BILGE – The interior of the hull below the floor boards. A bilge pump is a special device for this area.
BITTER END – The last part of a rope or chain.The inboard end of the anchor rode.
BOAT – A fairly indefinite term. A waterborne vehicle smaller than a ship. One boat definition is a small craft carried aboard a ship.
BOAT HOOK – A short shaft with a fitting at one end shaped to facilitate use in putting a line over a piling, recovering an object dropped overboard, or in pushing or fending off.
BOOT TOP – A painted line that indicates the designed waterline.
BOW – The forward part of a boat. The bow of a boat can also be referred to as the front. It’s the opposite of the stern of a boat in sailing terms.
BOW LINE – A docking line leading from the bow.
BOWLINE – A knot used to form a temporary loop in the end of a line.
BRIDGE – The location from which a vessel is steered and its speed controlled. “Control Station” is really a more appropriate term for small craft.
BRIDLE – A line or wire secured at both ends in order to distribute a strain between two points.
BRIGHTWORK – Varnished woodwork and/or polished metal.
BULKHEAD – A vertical partition separating compartments.
BUOY – An anchored float used for marking a position on the water or a hazard or a shoal and for mooring.
BURDENED VESSEL – That vessel which, according to the applicable Navigation Rules, must give way to the privileged vessel. The term has been superseded by the term “give-way”.
CABIN – A compartment for passengers or crew.
CAPSIZE – To turn over.
CAST OFF – To let go.
CATAMARAN – A twin-hulled boat, with hulls side by side.
CHAFING GEAR – Tubing or cloth wrapping used to protect a line from chafing on a rough surface.
CHART – A map for use by navigators.
CHINE – The intersection of the bottom and sides of a flat or v-bottomed boat.
CHOCK – A fitting through which anchor or mooring lines are led. Usually U-shaped to reduce chafe.
CLEAT – A fitting to which lines are made fast. The classic cleat to which lines are belayed is approximately anvil-shaped.
CLOVE HITCH – A knot for temporarily fastening a line to a spar or piling.
COAMING – A vertical piece around the edge of a cockpit, hatch, etc. to prevent water on deck from running below.
COCKPIT – An opening in the deck from which the boat is handled.
COIL – To lay a line down in circular turns.
COURSE – The direction in which a boat is steered.
CUDDY – A small shelter cabin in a boat.
CURRENT – The horizontal movement of water.
DEAD AHEAD – Directly ahead.
DEAD ASTERN – Directly aft.
DECK – A permanent covering over a compartment, hull or any part thereof.
DINGHY – A small open boat. A dinghy is often used as a tender for a larger craft.
DISPLACEMENT – The weight of water displaced by a floating vessel, thus, a boat’s weight.
DISPLACEMENT HULL – A type of hull that plows through the water, displacing a weight of water equal to its own weight, even when more power is added.
DOCK – A protected water area in which vessels are moored.The term is often used to denote a pier or a wharf.
DOLPHIN – A group of piles driven close together and bound with wire cables into a single structure.
DRAFT – The depth of water a boat draws.
EBB – A receding current.
FATHOM – Six feet.
FENDER – A cushion, placed between boats, or between a boat and a pier, to prevent damage.
FIGURE EIGHT KNOT – A knot in the form of a figure eight, placed in the end of a line to prevent the line from passing through a grommet or a block.
FLARE – The outward curve of a vessel’s sides near the bow. A distress signal.
FLOOD – A incoming current.
FLOORBOARDS – The surface of the cockpit on which the crew stand.
FLUKE – The palm of an anchor.
FOLLOWING SEA – An overtaking sea that comes from astern.
FORE-AND-AFT – In a line parallel to the keel.
FOREPEAK – A compartment in the bow of a small boat.
FORWARD – Toward the bow of the boat.
FOULED – Any piece of equipment that is jammed or entangled, or dirtied.
FREEBOARD – The minimum vertical distance from the surface of the water to the gunwale.
GALLEY – The kitchen area of a boat.
GANGWAY – The area of a ship’s side where people board and disembark.
GEAR – A general term for ropes, blocks, tackle and other equipment.
GIVE-WAY VESSEL – A term used to describe the vessel which must yield in meeting, crossing, or overtaking situations.
GRAB RAILS – Hand-hold fittings mounted on cabin tops and sides for personal safety when moving around the boat.
GROUND TACKLE – A collective term for the anchor and its associated gear.
GUNWALE – The upper edge of a boat’s sides. These are found on the sides of a boat.
HARD CHINE – An abrupt intersection between the hull side and the hull bottom of a boat so constructed.
HATCH – An opening in a boat’s deck fitted with a watertight cover.
HEAD – A marine toilet. Also the upper corner of a triangular sail.
HEADING – The direction in which a vessel’s bow points at any given time.
HEADWAY – The forward motion of a boat. Opposite of sternway.
HELM – The wheel or tiller controlling the rudder.
HELMSPERSON – The person who steers the boat.
HITCH – A knot used to secure a rope to another object or to another rope, or to form a loop or a noose in a rope.
HOLD – A compartment below deck in a large vessel, used solely for carrying cargo.
HULL – The main body of a vessel.
INBOARD – More toward the center of a vessel; inside; a motor fitted inside a boat.
INTRACOASTAL WATERWAY – ICW: bays, rivers, and canals along the coasts (such as the Atlantic and Gulf of Mexico coasts), connected so that vessels may travel without going into the sea.
JACOBS LADDER – A rope ladder, lowered from the deck, as when pilots or passengers come aboard.
JETTY – A structure, usually masonry, projecting out from the shore; a jetty may protect a harbor entrance.
KEEL – The centerline of a boat running fore and aft; the backbone of a vessel.
KNOT – A measure of speed equal to one nautical mile (6076 feet) per hour.
KNOT – A fastening made by interweaving rope to form a stopper, to enclose or bind an object, to form a loop or a noose, to tie a small rope to an object, or to tie the ends of two small ropes together.
LATITUDE – The distance north or south of the equator measured and expressed in degrees.
LAZARETTE – A storage space in a boat’s stern area.
LEE – The side sheltered from the wind.
LEEWARD – The direction away from the wind. Opposite of windward.
LEEWAY – The sideways movement of the boat caused by either wind or current.
LINE – Rope and cordage used aboard a vessel.
LOG – A record of courses or operation. Also, a device to measure speed.
LONGITUDE – The distance in degrees east or west of the meridian at Greenwich, England.
LUBBER’S LINE – A mark or permanent line on a compass indicating the direction forward parallel to the keel when properly installed.
MARLINSPIKE – A tool for opening the strands of a rope while splicing.
MIDSHIP – Approximately in the location equally distant from the bow and stern.
MOORING – An arrangement for securing a boat to a mooring buoy or a pier.
NAUTICAL – It’s easy to define nautical: it is an all encompassing word for anything concerning sailors or maritime travel. All of the boat terminology here can be defined as nautical words.
NAUTICAL MILE – One minute of latitude; approximately 6076 feet – about 1/8 longer than the statute mile of 5280 feet.
NAVIGATION – The art and science of conducting a boat safely from one point to another.
NAVIGATION RULES – The regulations governing the movement of vessels in relation to each other, generally called steering and sailing rules.
OUTBOARD – Toward or beyond the boat’s sides. A detachable engine mounted on a boat’s stern.
OVERBOARD – Over the side or out of the boat.
PIER – A loading platform extending at an angle from the shore.
PILE – A wood, metal or concrete pole driven into the bottom. Craft may be made fast to a pile; it may be used to support a pier (see PILING) or a float.
PILING – Support, protection for wharves, piers etc.; constructed of piles (see PILE)
PILOTING – Navigation by use of visible references, the depth of the water, etc.
PLANING – A boat is said to be planing when it is essentially moving over the top of the water rather than through the water.
PLANING HULL – A type of hull shaped to glide easily across the water at high speed.
PORT – The left side of a boat looking forward. A harbor.
PRIVELEGED VESSEL – A vessel which, according to the applicable Navigation Rule, has right-of-way (this term has been superseded by the term “stand-on”).
QUARTER – The sides of a boat aft of amidships.
QUARTERING SEA – Sea coming on a boat’s quarter.
RODE – The anchor line and/or chain.
ROPE – In general, cordage as it is purchased at the store. When it comes aboard a vessel and is put to use it becomes line.
RUDDER – A vertical plate or board for steering a boat.
RUN – To allow a line to feed freely.
RUNNING LIGHTS – Lights required to be shown on boats underway between sundown and sunup.
SATELLITE NAVIGATION – A form of position finding using radio transmissions from satellites with sophisticated on-board automatic equipment.
SCOPE – Technically, the ratio of length of anchor rode in use to the vertical distance from the bow of the vessel to the bottom of the water. Usually six to seven to one for calm weather and more scope in storm conditions.
SCREW – A boat’s propeller.
SCUPPERS – Drain holes on deck, in the toe rail, or in bulwarks or (with drain pipes) in the deck itself.
SEA COCK – A through hull valve, a shut off on a plumbing or drain pipe between the vessel’s interior and the sea.
SEAMANSHIP – All the arts and skills of boat handling, ranging from maintenence and repairs to piloting, sail handling, marlinespike work, and rigging.
SEA ROOM – A safe distance from the shore or other hazards.
SEAWORTHY – A boat or a boat’s gear able to meet the usual sea conditions.
SECURE – To make fast.
SET – Direction toward which the current is flowing.
SHIP – A larger vessel usually thought of as being used for ocean travel. A vessel able to carry a “boat” on board.
SLACK – Not fastened; loose. Also, to loosen.
SOLE – Cabin or saloon floor. Timber extensions on the bottom of the rudder. Also the molded fiberglass deck of a cockpit.
SOUNDING – A measurement of the depth of water.
SPRING LINE – A pivot line used in docking, undocking, or to prevent the boat from moving forward or astern while made fast to a dock.
SQUALL – A sudden, violent wind often accompanied by rain.
SQUARE KNOT – A knot used to join two lines of similar size. Also called a reef knot.
STANDING PART – That part of a line which is made fast.The main part of a line as distinguished from the bight and the end.
STAND-ON VESSEL – That vessel which has right-of-way during a meeting, crossing, or overtaking situation.
STARBOARD – The right side of a boat when looking forward.
STEM – The forward most part of the bow.
STERN – The after part of the boat in nautical terms. The stern of a boat is the back portion of the vessel. It is the opposite to the bow of a boat, which is the front.
STERN LINE – A docking line leading from the stern.
STOW – To put an item in its proper place.
SWAMP – To fill with water, but not settle to the bottom.
THWARTSHIPS – At right angles to the centerline of the boat.
TIDE – The periodic rise and fall of water level in the oceans.
TILLER – A bar or handle for turning a boat’s rudder or an outboard motor.
TOPSIDES – The sides of a vessel between the waterline and the deck; sometimes referring to onto or above the deck.
TRANSOM – The stern cross-section of a square sterned boat.
TRIM – Fore and aft balance of a boat.
UNDERWAY – Vessel in motion, i.e., when not moored, at anchor, or aground.
V BOTTOM – A hull with the bottom section in the shape of a “V”.
WAKE – Moving waves, track or path that a boat leaves behind it, when moving across the waters.
WATERLINE – A line painted on a hull which shows the point to which a boat sinks when it is properly trimmed (see BOOT TOP).
WAY – Movement of a vessel through the water such as headway, sternway or leeway.
WINDWARD – Toward the direction from which the wind is coming.
YACHT – A pleasure vessel, a pleasure boat; in American usage the idea of size and luxury is conveyed, either sail or power.
YAW – To swing or steer off course, as when running with a quartering sea.
Now that you know the basic boating terms, what about talking like a sailor. You’ll notice these are two very distinct things. While all of these official terms and names are important to know, there is more. If you spend a lot of time around sailors you may start picking up on boating slang. Less official but no less important, boating slang can convey just as much information as those other terms. Many of these come to us from the naval tradition, or even piracy, and some have gone beyond the nautical into our everyday lives.
Slang from Sailing Ships
A1: Not just a steak sauce, this slang term means something is high quality or the best. It comes from ship classifications. The highest rated ships were rated A1.
At Loggerheads: This term means to be locked in a disagreement. It comes from the term “loggerhead” which was a stick used to stir pitch and other hot liquids. If sailors got into a fight, they would sometimes use these loggerheads as weapons.
Barge In: Large, flat-bottom river barges are hard to maneuver. Thus, they had a bad habit of forcing their way into places where they weren’t wanted, which is where the modern meaning comes from.
Booty: Pirate booty is a phrase we’re all familiar with. It traces its origins to the word “bottyne” which was plunder taken in war.
By and Large: This term originally referred to how sails took the wind. By referred to the ability to sail into wind and large was off the wind. If a sailing ship could do both then by and large it sailed well.
Deep Six: This is used to mean getting rid of something. In nautical terms, a fathom was six feet, so you’d be dumping something one fathom, or about the height of a sailor, if you deep sixed them.
Devil and the Deep Blue Sea: This term refers to being between a rock and a hard place, as it were and this one does have a nautical origin and it does refer to the seam where the hell meets the deck. When a sailor did have to caulk this on the fly, they’d be suspended from the deck. The seam was called the devil, and the sea was right under them as they worked.
Hand Over Fist: This phrase typically refers to earning money, and means you’re pulling it in very fast. The phrase’s nautical origins refer to sailors rapidly pulling in ropes on a ship.
In the Soup: Fog is often described as being thicker than pea soup. If a boat is in the soup, it’s in the fog.
Keel Over: This slang term refers to passing out or even dying. The keel, of course, is located under a ship so for the keel to flip over the boat has to capsize. When applied to people the meaning is clear.
Knot: We knot nautical speed is measured in knots, but why? Back in the 17th century, sailors used something called the common log or chip log to measure speed. This consisted of a piece of wood used as a float at the end of a rope. Knots were tied in the rope every 47 feet 3 inches. A sailor would let these knots pass through their hands as the ship sailed, and the timing would be measured with a 30-second hour glass. The number of knots that passed through the sailor’s hands indicated speed.
Know The Ropes: Also “show you the ropes,” which means understanding how something is done. This one is fairly self-explanatory as any sailor hoping to master their ship would need to literally know the ropes and how to use them.
Limey: This is still used as a slang term, somewhat insultingly so, for British people. The phrase dates back to the British Navy providing its soldiers with rations of limes. Scurvy was a serious issue for sailors and it’s caused by a lack of vitamin C. The limes were meant to combat this.
Loose Cannon: A character in a TV show or movie is a loose cannon if they’re unpredictable. The term comes from cannons used on wooden ships. If a cannon was not secured, it would come loose on deck and could cause serious damage.
Pipe Down: This phrase means to be quiet or settle down. Boatswains would blow on a pipe to signal that it was time to head below deck in the evening. Piping down the hammocks was the term used.
Scuttlebutt: This is a term that means gossip. It dates back to sailing vessels and the literal scuttlebutt which was the term for water barrel. Sailors would gather around with a drinking ladle to chat when they had a moment free, hence its usage in terms of gossip.
Stinkpot: This is a modern term used by some boaters to refer to powerboats. In specific, the kind that race by very quickly and leave a wake of smelly exhaust.
Three Sheets to the Wind: A sheet is the line used to control a sail. One sheet left to flap in the wind would make control of the vessel harder. Three sheets means it’s downright sloppy and the sails would be all over the place. That’s why, today, the phrase refers to being drunk.
True Colors: When someone shows their true colors, it means they’re showing who they really are. In most contexts, this phrase means someone deceives you in some way but then you learned the truth. In nautical terms, some vessels would hide their flags or colors, and even fly the flags of enemies in order to trick people, especially in battle. If they had shown their true colors, the enemy would have known they were being tricked. Flying colors has the same origin.
Under the Weather: If you’re feeling ill, people will still use this phrase. It comes from the days of sailing when an ill sailor would be sent below deck. That kept you out of the weather which could make the situation worse by placing you literally under the weather.
The Slang That Didn’t Come From Sailing
Words and phrase origins are often steeped in myth, legend, and outright hoaxes. A lot of terms that allege to come from nautical origins are actually not nautical at all. You’ll find many websites that claim these stories as true origins. It’s always good to do a little extra research just to be sure. None of these terms and phrases are actually nautical at all.
Above Board: we use this term today to mean something that is honest or honorable. Some people claim it has a nautical origin. That a crew that stayed on deck was honest and, literally, above board. But if they were pirates they might hide below deck. This is not true, however, and the term traces its origins to gambling, not piracy.
As the Crow Flies: A popular story relating to this term is that vessels had crows in cages on board and would release one to see what direction it flew and then follow it to land. There is no evidence that this ever happened, however. Keeping birds alive in a cage would have been difficult, especially crows since they will fight each other.
Brass Monkey: A popular story is that pirate ships used to call the brass trays that held cannonballs brass monkeys. If it got cold enough, the metal would contract and the balls would fall off. However, that’s not actually true. Sailors never actually used the term “monkey” or “brass monkey” to describe anything on a ship. Also, cannonballs were never stored up on deck.
Buoyancy Operated Aquatic Transport: Ever heard this as the origin of the word “boat?” It’s not. That’s from a cartoon.
Cat out of the Bag: When you let the cat out of the bag, you reveal a secret. Some websites claim this has a nautical origin. The story goes that a sailor would be punished on board with a whip called a cat-o-nine tails. The whip was kept in a bag so to let the cat out of the bag meant something bad was happening. However, there is no evidence that this was ever used in a nautical context.
Clean Slate: People attribute this, meaning a fresh start, to sailors very often. However, the idea of a clean slate is literally as old as slates themselves. The Ancient Greeks had a concept called “tabula rasa” in philosophy which essentially translates to clean slate. Schools used to use chalk and slate before paper notebooks and every day those slates had to be cleaned. The phrase does not have any notable link to nautical history.
The Devil To Pay: This is a fun one that is often explained wrong. On a ship, the devil referred to the seam of the hull at deck level. Word is that this was the hardest of all seams to caulk, hence calling it the devil. The devil to pay meant caulking that seam. However, that is not the phrase origin. It looks more like sailors took the already existing phrase and used it to describe what they were doing. The true phrase predates nautical use by over 100 years. There is a lot of history of terms relating to people making bargains with the devil that require payment, including the very famous story of Faust.
Posh: A word used mostly in England to describe something fancy or expensive. There’s a story that it comes from ships that travelled from Britain to Boston. The rich customers were put in rooms labelled “port out, starboard home” as an instruction on where to store their luggage so it wouldn’t be ruined by the sun. This, however, is untrue.
Square Meal: This is another popular one from folk etymology. The story goes that sailors were fed on square plates thus the origin of square meal. And it’s true that the Royal Navy used square plates. However, the phrase was never recorded anywhere in naval history. But the word “square” meaning “good” or “proper” or “trustworthy” dates back hundreds of years. The first usage of “square meal” in print comes from US sources in advertisements.
The Whole Nine Yards: There are many supposed origins of this phrase, but one claims to be nautical. It suggests that square-rigged vessels with three sails on three masts had “the whole nine yards” out when all sails were up. However, there is no evidence to support this and it also doesn’t make much sense. Not all vessels had three sails or three masts.
Frequently Asked Questions
What is the back of a boat called?
The back section of a boat is referred to as the aft, while the actual back of a boat is known as the stern.
Where is the stern of a boat?
The stern of a boat is the back of a boat. In nautical terms, the bow is the front of a boat, and the stern is the rear.
Where is a boat’s gunwhale located?
A boat’s gunwhale is the top section of the boat’s sides. In ship terminology, a gunwhale definition is the upper edges of the side of boat.
Lucia Alonso on March 29, 2020
Tack: This term has two distinct meanings, both of them very important. As a verb, to tack is to change direction by turning the bow of the boat through the wind. As a noun, your tack is the course you are on relative to the wind. For example, if the wind is blowing over the port side, you are on a port tack. If it s blowing over the starboard side, you re on a you guessed it starboard tack.
Joe H. on April 12, 2023
The tack of a sail refers to the bottom forward attachment point on a (Bermuda Rig/Marconi Rig/Gaff Rig) sail attached directly to the mast. Depending which sail type being used the top attachment point may be called the head or the peak, the bottom attachment point at the mast is called the tack , and the furthest back attachment point is called the clew.
kathy fuller on June 21, 2020
Is the sign SCREWROOM really used on a boat?
Cynthia Fuller on March 24, 2022
What is the term for piling rope on deck in the shape of a figure eight?
Tony H on June 7, 2022
The pass thru hole , on some vessels, for a Line to pass thru to tie to an inboard cleat, is called?
Jack Ducan on February 28, 2023
The word wale in gunwale was used to refer to the upper plank on the boat. The plank used for the wale was a lot thicker than any regular planking as it was there to lessen the damage to the vessel and people.