Sailing terms and nautical glossary
Find clear definitions of sailing terms, boat parts, knots, navigation and nautical abbreviations. New to sailing? Start with the everyday words below, then explore the full glossary by subject or search for a term.
Sailing terms for beginners
Begin with port and starboard, bow, windward and leeward. Learn how sheets and halyards control sails, then explore points of sail, tacking and gybing.
For terms in context, read our beginner sailing vocabulary guide. Ready to practise on the water? Our first sailing course guide explains how to choose a starting route.
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TermDefinition
- General Nautical Terminology, Nautical Topics, Signals & Communication Ready to Receive (Flag Semaphore)
A semaphore procedural signal confirming that the receiving station is prepared to copy the message.
It is shown in response to the sender’s...
More Details - General Nautical Terminology, Nautical Topics, Safety Recovery Sling
A sling designed to support and lift a person during recovery from the water.
It is passed around or attached to the casualty and connected to...
More Details - Abbreviation, General Nautical Terminology, Light Characteristic, Nautical Topics, Navigation, Signals & Communication Red Light or Mark (R)
The code R identifies a red charted light, buoy or beacon.
Its position within the aid-to-navigation description distinguishes it from R...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat Reef Clew
The reinforced clew point that becomes the after lower corner of a reefed sail.
It is pulled down and aft to the boom so the reefed foot and...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat Reef Cringle
A reinforced eye in a sail used as an attachment point when reefing.
Tack and clew cringles take the principal loads of the shortened sail,...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat, Points of Sail, Safety Reefing
Reducing a sail's exposed area to control power and loads as wind or sea conditions increase.
A slab-reefed mainsail is lowered sufficiently...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat, Points of Sail, Safety Reefing Hook
A hook used to secure a mainsail's reef tack or cringle near the gooseneck.
Often called a ram's horn, it holds the selected reef cringle at...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat, Points of Sail, Safety Reefing Lines
Lines forming part of a system that reduces and secures a sail's exposed area.
On slab-reefed mainsails, reefing lines commonly pull a reef...
More Details - General Nautical Terminology, Knot, Nautical Topics, Mooring & Berthing Reef Knot
A binding knot formed by two opposing half knots, used to hold a bundle or gather material.
Traditional uses include tying reef points around...
More Details - General Nautical Terminology, Nautical Topics, Points of Sail Reef Tack
The reinforced tack point used to secure the forward lower corner of a reefed sail.
When a reef is taken, the reef tack is brought down and...
More Details - General Nautical Terminology, Nautical Topics, Depths & Clearance, Navigation, Safety, Sea State & Waves Reef (Underwater Feature)
A ridge, chain or area of rock, coral or other consolidated material lying at or near the water surface.
Reefs may be biogenic, volcanic,...
More Details - General Nautical Terminology, Nautical Topics, Navigation Relative Bearing
The direction of an object measured clockwise from a vessel's heading.
It is normally expressed from 000° directly ahead through 090° on the...
More Details - General Nautical Terminology, Nautical Topics, Weather (Meteorology) Relative Humidity
The amount of water vapour in air expressed as a percentage of the saturation amount at the same temperature.
The percentage can rise as air...
More Details - General Nautical Terminology, Nautical Topics, Mooring & Berthing Render a Line
To allow a rope to run out under controlled tension around a fitting or through a lead.
Rendering prevents a sudden uncontrolled release while...
More Details - Abbreviation, General Nautical Terminology, Nautical Topics, Navigation Reported Charted Feature (Rep)
Based on reported information that may not have been fully surveyed or confirmed.
Rep is often followed by the year of the report.
- General Nautical Terminology, Nautical Topics, Safety Reserve Buoyancy
The watertight volume above a vessel's loaded waterline that remains available to oppose further immersion.
Adequate freeboard and intact...
More Details - General Nautical Terminology, Nautical Topics, Parts of a Boat, Points of Sail Resistance (Vessel Motion)
The force opposing a vessel’s movement through the water.
Components include skin friction, pressure effects and wave-making, with their...
More Details - General Nautical Terminology, Nautical Topics, Signals & Communication Rest (Flag Semaphore)
A neutral semaphore position with both flags lowered, used when resting or not actively transmitting.
The same physical position may mark a...
More Details - General Nautical Terminology, Nautical Topics, Navigation, Safety, Signals & Communication Restricted in Ability to Manoeuvre (RAM) (RAM)
A vessel restricted by the nature of its work in its ability to manoeuvre as required by the collision regulations and therefore unable to keep...
More Details - General Nautical Terminology, Nautical Topics, Navigation, Safety, Signals & Communication, Weather (Meteorology) Restricted Visibility
Any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or another similar cause.
In the...
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