Yachting Encyclopedia

navigation

AIS

The Automatic Identification System (AIS) is an automated tracking system that transmits vessel identity, position, course, and speed via VHF radio frequencies to nearby ships and shore stations for collision avoidance.

sailing

Anchor chain

The chain connecting the anchor to the vessel, part of the ground tackle.

sailing

Anchor scope

The ratio of the length of anchor rode (chain and/or rope) paid out to the vertical distance from the bow roller to the seabed.

sailing

Anchor

A heavy device dropped to the seabed or streamed in open water to hold a vessel in place by mechanical grip or hydrodynamic drag.

navigation

Apparent wind

The speed and direction of the wind observed relative to a moving vessel, formed by the vector sum of the true wind velocity and the headwind caused by the boat's movement.

boatbuilding

Ballast

In yachting: weight placed low in a vessel, often in the keel, to lower the centre of gravity and increase stability. It can be fixed (lead, iron) or water ballast in tanks.

sailing

Beam reach

A point of sail where the boat travels at approximately 90° relative to the true wind direction, perpendicular to its centerline.

boatbuilding

beam (width)

The maximum width of a vessel’s hull, measured at the widest point excluding appendages.

navigation

Bearing

The horizontal angle measured clockwise from a reference north meridian to the line of sight toward an object, expressed from 000° to 360°.

sailing

Berth

A versatile nautical term denoting a designated space for mooring a vessel, a sleeping accommodation aboard, or a safe navigational distance from hazards.

sailing

Boom vang (Kicking strap)

A running rigging component that applies downward force on the boom to control mainsail leech tension and shape.

sailing

Boom

A horizontal spar attached to the mast at its forward end, used to extend and control the foot of a fore-and-aft main sail.

boom ~

boatbuilding

Bow

The forwardmost part of a ship or yacht's hull, designed to slice through water and provide reserve buoyancy.

sailing

Broad reach

A broad reach is a point of sail relative to the wind where the true wind blows onto the vessel from behind the beam, angled between 110° and 160° from the bow.

navigation

Buoyage

A system of floating and fixed aids to navigation used to indicate channels, navigational hazards, safe water, and special areas.

boatbuilding

Cabin

A cabin is an enclosed space on a yacht or ship used for accommodation, sleeping, or work by crew and passengers.

navigation

Cardinal mark

A navigational mark indicating the safe side of a hazard relative to the cardinal compass points.

sailing

Catamaran

A multihull vessel featuring two parallel hulls of equal size joined by a connecting bridge or deck structure, deriving its initial stability from hull beam width rather than a ballast keel.

sailing

Cleat (Horn Cleat)

A T-shaped deck fitting with two opposing horns used to secure mooring lines, halyards, and sheets.

sailing

Close-hauled

The point of sail closest to the wind (typically 30°–45° to the apparent wind), where sails are sheeted in tightly to generate aerodynamic lift.

boatbuilding

Cockpit

An open or partially enclosed area on the deck of a yacht where the controls are located and the crew operates.

safety

COLREGs

The International Regulations for Preventing Collisions at Sea (COLREGs) are the global IMO-mandated rules establishing navigation standards, right-of-way, and signaling for vessels at sea.

navigation

Course

Course is the horizontal direction in which a vessel is steered or intended to be steered, measured as an angle in degrees from 000° clockwise to 360° relative to a reference meridian.

boatbuilding

Deck

A deck is a permanent covering over a compartment or the hull of a vessel, serving as a floor for crew, passengers, and gear, while also contributing to the longitudinal and transverse strength of the structure.

navigation

Depth sounder

An electronic acoustic instrument that measures water depth underneath a vessel's hull by calculating the travel time of ultrasonic sound pulses reflected from the seabed.

boatbuilding

Displacement

Displacement is the weight or volume of water displaced by a floating vessel, equal to the total mass of the yacht according to Archimedes' principle.

boatbuilding

Draught

The vertical distance between the waterline and the lowest point of a vessel's hull, keel, or rudder.

safety

EPIRB (Emergency Position Indicating Radio Beacon)

An EPIRB is a vessel-registered emergency transmitter designed to broadcast distress signals on 406 MHz to rescue authorities via the Cospas-Sarsat satellite system.

sailing

Fender

A resilient bumper device (typically air-filled PVC, polyurethane elastomer, or foam) deployed along a vessel's hull to absorb kinetic energy and prevent damage during mooring or ship-to-ship berthing.

boatbuilding

Freeboard

Freeboard is the vertical distance measured from the waterline to the upper deck level at the lowest point where water can enter the vessel.

sailing

Genoa sail

A genoa sail is a large overlapping headsail whose clew extends aft past the mast line.

navigation

GPS (Global Positioning System)

A satellite-based radionavigation system providing precise geographic coordinates, speed over ground, and course over ground for vessels worldwide.

sailing

Gybe

A gybe (also spelled jibe) is a sailing maneuver in which the stern of a vessel passes through the wind line, shifting the mainsail and boom from one side of the boat to the other while sailing downwind.

sailing

Halyard

A line of running rigging used to hoist a sail, yard, flag, or ladder up a mast or stay.

navigation

Heading

Heading is the direction in which the longitudinal axis (bow) of a vessel is pointed at any given moment, measured in degrees from 000° to 359° clockwise from North.

safety

Heave-to

A seamanship maneuver where sails and rudder are set in opposition to bring a sailing vessel to a relative stop and controlled drift.

heave-to

boatbuilding

Hull

The watertight structural shell of a vessel that provides buoyancy, stability, and structural integrity under hydrodynamic and aerodynamic loads.

sailing

Jib

A triangular headsail set forward of the mast along the forestay, providing primary aerodynamic drive and steering balance.

boatbuilding

Keel

The central longitudinal structural element at the bottom of a hull, or a weighted underwater fin that provides stability and resists lateral leeway on modern sailing vessels.

navigation

Knot (unit of speed)

A nautical unit of speed equal to one nautical mile per hour (exactly 1.852 km/h or approximately 0.514 m/s).

navigation

Lateral mark

A sea mark used in the IALA Maritime Buoyage System to indicate the port or starboard edge of a channel relative to the direction of buoyage.

navigation

Latitude

Geographical latitude is the angular distance of a location north or south of the Earth's equator, expressed in degrees from 0° at the equator to 90° at the poles.

sailing

Leech

The aft (trailing) edge of a triangular sail, running between the head and the clew.

sailing

Leeward

The direction downwind from a reference point, or the side of a vessel sheltered from the wind.

safety

Life jacket

A personal flotation device designed to keep an unconscious person's head above water with airway clear.

safety

Life raft

A self-inflating collective lifesaving appliance designed to keep survivors afloat and protected from exposure after abandoning a vessel.

navigation

Longitude

Geographic longitude is the angular distance measured east or west from the Prime Meridian (Greenwich) to the meridian of a given point, ranging from 0° to 180° E or W.

sailing

Luff

The leading edge of a sail, extending from head to tack, and the action of turning the bow of a sailboat into the wind.

navigation

Magnetic compass

A self-contained navigation instrument that utilizes Earth's magnetic field to indicate vessel heading and bearings.

sailing

Mainsail

A mainsail is the primary sail rigged on and behind the main mast of a fore-and-aft rigged sailing vessel.

safety

Man Overboard

An emergency situation where a crew member or passenger falls off a vessel into the water, as well as the standard emergency shout and recovery maneuver.

navigation

Marine Radar

An active radio detection system emitting microwave pulses to measure range and bearing to targets for collision avoidance and navigation in poor visibility.

sailing

Mast

A tall vertical spar or extruded profile erected along the centerline of a vessel to support sails, standing rigging, and navigational hardware.

radio

MAYDAY

The international standard radiotelephone distress signal transmitted over VHF/HF radio to indicate grave and imminent danger to a vessel or human life.

sailing

Monohull

A monohull is a vessel featuring a single hull structure, relying on a weighted ballast keel to provide righting moment and transverse stability under sail.

sailing

Mooring line

A high-elasticity synthetic rope used to secure a vessel to a quay, pier, mooring buoy, or alongside another vessel.

navigation

Nautical chart

A graphic representation of a maritime area and adjacent coastal regions, providing detailed information on water depths, hazards, channels, and aids to navigation.

navigation

Nautical Mile

A unit of distance used in marine and air navigation, defined internationally as exactly 1,852 meters.

sailing

Outhaul

A control line in the running rigging of a sailboat that attaches the mainsail clew to the boom and adjusts the tension along the foot of the sail.

radio

PAN-PAN

The international radiotelephone urgency signal, broadcast three times ("PAN-PAN, PAN-PAN, PAN-PAN") on VHF Channel 16 to indicate an urgent situation concerning the safety of a vessel or person without immediate grave danger.

sailing

Port

A nautical term denoting the left side of a vessel when facing forward towards the bow, a sailing vessel's wind orientation (port tack), or a harbor facility.

sailing

Rudder

An underwater hydrodynamic blade forming part of a vessel's steering system, used to control or alter the yacht's heading by deflecting water flow.

sailing

Running Downwind

A point of sail where a vessel travels in the same direction as the true wind, at an angle of approximately 180° (typically between 170° and 190°).

sailing

Sail foot

The bottom edge of a sail, running between the tack and clew.

sailing

Sail Reefing

The practice of reducing a sail's active surface area to maintain vessel stability, reduce heel, and preserve control in strong winds.

sailing

Sailboat Winch

A mechanical deck device featuring a rotating drum, internal gear assembly, and ratchet mechanism used to multiply human force when tensioning sheets, halyards, and control lines.

safety

Sea anchor

A heavy-weather drag device deployed from the bow of a vessel to hold its head into the wind and waves, significantly reducing downwind drift.

sailing

Sheet

A running rigging line used to trim a sail by controlling its angle relative to the wind and its tension.

sailing

Shroud

A shroud is a cable or rod forming part of a sailing vessel's standing rigging, providing lateral support to the mast and transferring wind loads to the hull.

sailing

Spinnaker

A spinnaker is a large, lightweight sail designed specifically for downwind sailing on courses from a reach to a run (wind angles 90°–180°).

sailing

Starboard

Starboard is the right side of a vessel when facing forward toward the bow, identified at night by a green navigation sidelight.

sailing

Stay

A fore-and-aft standing rigging cable or rod that supports a sailboat's mast against longitudinal loads.

boatbuilding

Stern

The stern is the rear or aft-most section of a vessel's hull, directly opposing the bow and housing steering gear, transom structures, and navigation lights.

navigation

Tack

A tack defines both the orientation of a sailing vessel relative to the wind (port tack or starboard tack) and the maneuver of turning the bow through the wind eye to change sides.

sailing

Telltale

A lightweight strip of yarn or tape (6–8 in / 15–20 cm) attached to a sail to visually indicate airflow and guide precise sail trim.

boatbuilding

Transom

Transom — the flat or curved transverse surface forming the stern of a vessel, used for mounting engines, rudders, and other equipment.

sailing

Traveller

A traveller is a car that slides along a transverse track, to which the mainsheet block is attached, allowing the sheet's attachment point to be adjusted athwartships to control sail shape.

meteorology

True wind

True wind is the speed and direction of the airflow over the water surface relative to a stationary observer or land, unaffected by the motion of the vessel.

radio

VHF marine radio

A VHF marine radio is a combined transmitter and receiver operating in the VHF maritime mobile band (156–174 MHz), used worldwide for vessel safety, inter-ship communication, and navigation control.

boatbuilding

Waterline

The waterline is the intersection of the surface of the water with the hull of a vessel, varying with load.

navigation

Waypoint

A specific geographic location defined by coordinates (latitude and longitude) used in marine electronic navigation to delineate routes, turning points, or hazards.

sailing

Windward

The direction from which the wind is blowing, or the side of a vessel facing into the wind.

sailing

Yacht marina

A purpose-built, sheltered harbor designed to provide secure berthing, infrastructure, utilities, and maintenance services for recreational vessels and yachts.