Glossary of Basic Nautical Terms

Glossary of Basic Nautical Terms

A sail with a windward clew that is pressed back towards the mast (typically caused by a sudden change of wind).

Toward the rear (stern) of the boat. Behind.

At right angles to the keel of the boat, but not on the boat.

On or within the boat.

On the deck (not over it see aloft).

Side by side; by the side of.

Loose, not on moorings or towline. Also refers to free floating object or boat that cannot move by its own power.

Toward the stern of the boat.

Touching or fast to the bottom.

In a forward direction.

A boat lies ahull when it is drifting with no sails set.

aids to navigation

Artificial objects to supplement natural landmarks indicating safe and unsafe waters.

Away from the direction of the wind. Opposite of windward.

Above the deck of the boat (overhead).

In or toward the center of the boat.

A place suitable for anchoring in relation to the wind, seas and bottom.

anchor light

See riding light.

An instrument for measuring wind speed.

apparent wind

The wind that flows over a moving boat.

In back of the boat; opposite of ahead.

athwartships

At right angles to the centerline of the boat; rowboat seats are generally athwartships.

The position of the anchor as it is raised clear of the bottom.

backing a sail

To push a sail out so that the wind fills the opposite side.

A stay used to halt any forward movement of the mast.

Weight, usually metal, placed low in the boat.

bare poles (to sail under)

Sailing without any sails set.

Light wood or plastic inserted into a sail's pocket for leech support.

batten down

Secure hatches and loose objects both within the hull and on deck.

The greatest width of the boat.

bear away (or off)

To alter course away from the wind.

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.

See close hauled.

A loop at a rope's end.

To secure or fasten down a line.

Beneath the deck.

The part of the rope or line, between the end and the standing part, on which a knot is formed.

The interior of the hull below the floor boards.

Small posts fixed through the vessel's foredeck.

The last part of a rope or chain. The inboard end of the anchor rode.

A fairly indefinite term. A waterborne vehicle smaller than a ship. One definition is a small craft carried aboard a ship or a small, open craft (without a deck).

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.

A stay from the bow of the boat to the end of the bowspirt.

Rope sown into the edge of the sail as reinforcement.

A spar for extending the foot of the sail.

A tackle attached to a boom to prevent it from lifting.

A painted line that indicates the designed waterline.

bosun's chair

A canvas seat used to hoist a person up a mast.

The forward part of a boat.

A docking line leading from the bow.

A knot used to form a temporary loop in the end of a line.

A spar that projects from the bow, allowing the head sails to be secured further forward.

The location from which a vessel is steered and its speed controlled. "Control station" is really a more appropriate term for small craft.

A line or wire secured at both ends in order to distribute a strain between two points.

Varnished woodwork and/or polished metal.

bring about

To change direction.

When a vessel that is running before a sea turns inadvertently and is hit broadside by oncoming waves.

A vertical partition separating compartments.

An anchored float used for marking a position on the water, or a hazard or a shoal for mooring.

This is a vessel's ability to stay afloat.

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."

A compartment for passengers or crew.

A nautical measurement equaling one tenth of a nautical mile.

A twin-hulled boat, with hulls side by side.

centerboard

A pivoting or sliding plate that extends the keel.

An imaginary line running down the middle of the ship from the bow to the stern.

chafing gear

Tubing or cloth wrapping used to protect a line from chafing on a rough surface.

A map for use by navigators.

The intersection of the bottom and sides of a flat or "V" bottomed boat.

A fitting through which an anchor or mooring lines are led. Usually U-shaped to reduce chafe.

A deck opening near the bow from which a spinnaker is hoisted.

A category of vessels having a similar design.

A C-shaped fitting that slips over a boom.

A fitting to which lines are made fast. The classic cleat to which lines are belayed is approximately anvil-shaped.

The lower aft corner of a fore and aft sail.

close hauled

A vessel with its sheets pulled in for sailing as close to the wind as possible.

clove hitch

A knot for temporarily fastening a line to a spar or piling.

A vertical piece around the edge of a cockpit, hatch, etc. to prevent water on deck from running below.

An opening in the deck from which the boat is handled.

coffee grinder

A large, powerful winch for handling sails.

To lay a line down in circular turns.

Switching from one tack to another when sailing into the wind.

Coordinated Universal Time

A replacement of Greenwich Mean Time. It is time standard that is unaffected by seasons and time zones.

The direction in which a boat is steered.

A small shelter cabin in a boat.

The horizontal movement of water.

A single mast fore-and-aft sailing boat with an outer jib as well as an inner staysail.

daggerboard

A centerboard that may be raised and lowered straight up and down.

An open boat used for daytime sailing.

Directly ahead.

dead astern

A permanent covering over a compartment, hull or any part thereof.

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.

A protected water area in which vessels are moored. The term is often used to denote a pier or a wharf.

Screen of cloth or other material fitted to protect passengers from the wind and water spray.

A group of piles driven close together and bound with wire cables into a single structure.

double ender

Any vessel with a pointed bow and stern.

Tackle used for pulling down the tack.

The depth of water a boat draws.

The depth of water required to float a vessel.

A wind-filled sail.

Object towed over the stern to slow a boat and to keep it pointed downwind.

Letting out a sail or line gradually.

A receding (falling) current.

Refers to a country's national flag that is flown at the stern.

Any device that guides a rope.

The part of the tackle which is hauled upon.

A cushion, placed between boats, or between a boat and a pier, to prevent damage.

The distance a wind has to travel over open water.

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.

A single weighted keel that is centrally attached to a vessel's bottom (for stability).

The outward curve of a vessel's sides near the bow. A distress signal.

An incoming current.

floorboards

The surface of the cockpit on which the crew stands.

Vessel contents or equipment that have been washed overboard.

The points of an anchor which dig into the soil of the bottom.

following sea

An overtaking sea that comes from astern.

A sail's lower edge.

Towards, near or at the bow.

fore-and-aft

In a line parallel to the keel.

A space in the bows of a vessel.

Fore-and-aft sails set on a foremast.

A stay leading from the mast to the foredeck that is used to hoist staysails and to stabilize the mast.

forestaysail

A triangular sail set forward of the mast on the forestay.

Toward the bow of the boat.

To entangle or obstruct.

The minimum vertical distance from the surface of the water to the gunwale.

Folding and securing a sail to its boom or spar.

A spar which extends the head of a fore-and-aft mainsail.

The kitchen area of a boat.

The area of a ship's side where people board and disembark.

A general term for ropes, blocks, tackle and other equipment.

A headsail that extends from bow to behind the mast.

A system by which an object is suspended so that it remains horizontal as the boat heels.

give-way vessel

A term used to describe the vessel which must yield in meeting, crossing or overtaking situations.

The fitting on a mast where a boom is attached.

Hand-hold fittings mounted on cabin tops and sides for personal safety when moving around the boat.

A ring of rope or metal fastened in a sail awning.

ground tackle

A collective term for the anchor and its associated gear.

A part of the rudder assembly which permits the rudder to pivot.

The upper edge of a boat's sides.

A line used to hoist sails.

Rings or hooks for attaching sails to stays.

An abrupt intersection between the hull side and the hull bottom of a boat so constructed.

An opening in a boat's deck fitted with a watertight cover.

A marine toilet. Also the upper corner of a triangular sail.

The direction in which a vessel's bow points at any given time.

A sail set forward of the main mast on the headstay.

A stay that leads from the mast to the bow.

The forward motion of a boat. Opposite of sternway.

To rig a boat so that it lies to the wind and sea with as little movement as possible.

The wheel or tiller controlling the rudder.

helmsperson

The person who steers the boat.

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.

A compartment below deck in a large vessel, used solely for carrying cargo.

The main (outer) body of a vessel.

The maximum speed a hull can achieve without planing.

See intracoastal waterway

More toward the center of a vessel; inside; a motor fitted inside a boat.

A vessel that has stopped head to wind.

intracostal waterway

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.

Rigged line to which safety harnesses may be clipped.

Jacob's ladder

A rope ladder, lowered from the deck, used when pilots or passengers come aboard.

A cleat that allows a line to be fastened quickly by jamming it down.

Anything thrown overboard.

A structure, usually masonry, projecting out from the shore; a jetty may protect a harbor entrance.

A vessel's foremost sail.

Swinging a fore-and-aft sail sideways when running before the wind.

A temporary replacement of any part of any broken rigging.

A small auxiliary anchor.

Moving a vessel by setting out a kedge and hauling the boat forward by taking up the anchor rode.

The centerline of a boat running fore and aft; the backbone of a vessel.

A two-masted fore-and-aft rigged boat with the forward mast also serving as the main mast.

A vertical post used as a support.

A measure of speed equal to one nautical mile (6076 feet or 1.85 km) per hour.

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.

A length of line or thin rope.

A short line used to attach one thing to another.

A large foresail which extends aft behind the mast.

A rope used for securing any movable object in place.

The distance north or south of the equator measured and expressed in degrees.

To store a yacht away for the winter.

A storage space in a boat's stern area.

A lead weight which is attached to the line to find out how much water is below the boat.

The side sheltered from the wind.

Boards attached vertically to a vessel to prevent leeway.

The aftermost edge of a fore-and-aft sail.

The direction away from the wind. Opposite of windward.

The sideways movement of the boat caused by either wind or current.

A stationary vessel that carries a navigational light.

Rope and cordage used aboard a vessel.

A permanent record of daily progress and operations. Also, a device to measure speed.

The distance in degrees east or west of the meridian at Greenwich, England.

A system of long range radio navigation used to find position.

lubber's line

A mark or permanent line on a compass indicating the direction forward parallel to the keel when properly installed.

The forward edge of a fore-and-aft sail.

lug or lugsail

A four-sided sail bent onto a yard.

A boat rigged with lugsails.

An object used as a reference point while navigating.

marlinspike

A tool for opening the strands of a rope while splicing.

A pole or spar placed vertically for hoisting sails.

The top of a mast.

masthead sloop

A sloop with a headstay that reaches the masthead.

A recess or fitting in a vessel's keel where the base of the mast is set.

Approximately in the location equally distant from the bow and stern.

A unit of barometric pressure.

mizzen (or mizzen mast)

The aftermost mast of a ketch or yawl.

To fasten a vessel to a mooring.

An arrangement for securing a boat to a mooring buoy or a pier.

Small passages.

Nautical Almanac

An annually published book filled with astronomical and tidal information.

nautical mile

One minute of latitude; approximately 6076 feet, about 1/8 longer than the statute mile of 5280 feet.

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.

Tides with smaller range than spring tides two days after the first and last quarters of the moon.

An area that cannot be entered by a boat without tacking.

Any point of sailing away from the wind.

Any boat built to conform to a rule so that it is identical to all other boats.

Toward or beyond a boat's sides. Also a detachable engine mounted on a boat's stern.

A rope which hauls aft on the clew of the main sail.

To sail closer to the wind than another boat.

Over the side or out of the boat.

A wave that breaks sharply over a shoal or a point where currents meet.

A rope attached to the bow of a small boat.

The deck opening through which the mast passes.

The upper corner of a four-sided sail.

A long triangular flag.

A loading platform extending at an angle from the shore.

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.

Support, protection for wharves, piers etc.; constructed of piles (see pile).

Navigation by use of visible references: the depth of the water, etc.

To sail too close to the wind.

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.

The covering of a vessel's ribs.

To sail very close to the wind.

A raised deck on the after part of the ship.

The left side of a boat looking forward. A harbor.

position line or "line of position"

A position line is a line along which the boat is positioned.

An extra stay line used to prevent jibing booms.

privileged vessel

See stand-on vessel.

The sideways effect of the propeller on the stern.

The bow and fore part of a vessel.

An elevated guardrail on a vessel's bow or stern.

Flat-bottomed boat that is square at either end.

The sides of a boat aft of amidships (midway between the beam and stern).

quarter berth

A bunk which runs under the cockpit.

quartering sea

Sea coming on a boat's quarter.

A strong, confused tide or current.

A method of measuring certain dimensions of yachts.

Small lines that form steps to function as a ladder to climb the rigging.

To sail with the wind.

To reduce the sailing area by folding or rolling.

To pass something through a hole.

The wood that forms the boat's frame.

To lie at anchor.

riding light

An all around white light.

The arrangement of a vessel's spars and sails.

A vessel's wiring and rope system.

The curved leech of a sail.

The anchor line and/or chain.

In general, cordage as originally purchased. When it comes aboard a vessel and is put to use it becomes line.

A space in the gunwale for an oar.

A vertical plate or board for steering a boat.

rudder post

A boat's aftermost timber.

To allow a line to feed freely.

running backstay

A movable backstay.

running lights

Lights required to be shown on boats underway between sundown and sunup.

running rigging

A generic term for sheets and halyards.

safety harness

A harness worn by crew and tethered to a boat, preventing the crew from falling overboard.

Sampson post

A strong vertical post where lines are attached.

satellite navigation

A form of position finding using radio transmissions from satellites with sophisticated on-board automatic equipment.

A boat with two or more masts.

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.

A boat's propeller.

Drain holes on deck, in the toe rail, or in bulwarks or (with drain pipes) in the deck itself.

A drogue or drag device to slow down a boat.

A through hull valve, a shut off on a plumbing or drain pipe between the vessel's interior and the sea.

All the arts and skills of boat handling, ranging from maintenance and repairs to piloting, sail handling, marlinspike work and rigging.

A safe distance from the shore or other hazards.

A boat or a boat's gear able to meet the usual sea conditions.

To hoist the sails into sailing position.

A navigational instrument for measuring the altitude of celestial bodies.

An anchor's main shaft.

The pulley wheel in a block.

The straight or curved portion of a deck line.

A rope attached to a sail's clew.

The metal casing of a block which holds a pin.

A larger vessel typically meant for ocean travel. A vessel able to carry a "boat" on board.

Stays that provide mast support.

side lights

Navigation lights, green is to starboard, red to port.

To cast off all but one remaining line.

Projecting portion of the underwater part of a vessel.

Not fastened; loose. Also, to loosen.

To let go purposely.

A single-masted vessel.

snatch block

A block into which a line can be placed without being threaded.

Speed Over Ground, speed relative to bottom.

Cabin or saloon floor. Timber extensions on the bottom of the rudder. Also the molded fiberglass deck of a cockpit.

A measurement of the depth of water.

Another term for mast.

To shake the wind out of a sail.

A lightweight three-cornered sail.

A method of joining ropes without the use of knots.

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.

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.

A post used to support guardrails and lifelines.

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.

standing rigging

The shroud and stays that provide mast support.

stand-on vessel

That vessel which has right-of-way during a meeting, crossing or overtaking situation.

The right side of a boat when looking forward.

The part of the standing rigging that supports the mast in fore-and-aft direction.

A triangular headsail that is hanked to a forestay.

steerage way

Sufficient movement through the water to allow the boat to be steered by the rudder.

The forward-most part of the bow.

A recess into the keel in which the mast is placed.

The after part of the boat.

A docking line leading from the stern.

An elevated guardrail at a vessel's rear.

Small lines used to tie the sails when furled.

To put an item in its proper place.

To fill with water, but not settle to the bottom.

To haul up tight.

The forward lower corner of a fore-and-aft sail.

A zig-zag course that is used to make progress against the wind.

A system using ropes and blocks.

A metal fitting that attaches stays to the mast.

Small lengths of wool sewn on the sail.

A small boat used to ferry passengers to shore from a larger vessel.

A metal loop for forming a hard eye.

A seat running across a dinghy.

thwartships

At right angles to the centerline of the boat.

tidal current

The horizontal movement of the water due to tide.

The periodic rise and fall of water level in the oceans.

Part of a channel where the tide is the strongest.

A bar or handle for turning a boat's rudder or an outboard motor.

topping lift

A tackle or rope used to support a boom.

The sides of a vessel between the waterline and the deck; sometimes referring to onto or above the deck.

Prospective course for a boat to follow.

The stern cross-section of a square-ended boat.

A slide which travels on a track.

Fore and aft balance of a boat.

Fishing with light baited lines.

The speed and direction of the wind from the vantage point of a stationary object.

A triangular loose-footed sail fitted aft of the mast.

A device used to maintain the proper tension on standing rigging.

Vessel in motion; i.e., when not moored, at anchor, or aground.

A hull with the bottom section in the shape of a "V."

Moving waves, track or path that a boat leaves behind it, when moving across the waters.

To warp is to move a vessel by lines.

Boards used to close a companionway.

A line painted on a hull which shows the point to which a boat sinks when it is properly trimmed (see boot top).

Movement of a vessel through the water such as headway, sternway or leeway.

A charted feature or chosen position on a chart.

weigh anchor

To raise the anchor from the bottom.

Method of binding ropes.

whisker pole

A pole used to boom out of the jib when running wing and wing.

Toward the direction from which the wind is coming.

A pleasure vessel, a pleasure boat; in American usage, the idea of size and luxury is conveyed, either sail or power.

A spar from which a square sail is hung.

To swing or steer off course, as when running with a quartering sea.

Two-masted fore-and-aft rigged vessel.

A gentle breeze; the slightest movement of air.

See Coordinated Universal Time.