Glossary

Unit of measure (distance)

A cable is a unit of distance traditionally used to measure short distances at sea. It is generally considered...

The CADET mnemonic can help remember the corrections needed when converting between True North and Compass North bearings. It assists in...

A unique identifier assigned to a vessel or maritime station for communication purposes, typically used in radio transmissions.

A call sign is...

A mechanical device with spring-loaded, opposing cams that grip a rope or line to hold it securely while allowing for quick adjustments. 

A...

Cancel (or Disregard) informs the receiver to disregard the previous message or cancel the signalling. There is no specific attachment to...

Cardinal Bearings are the main points on a compass, expressed by their name. There are four main cardinal points, North, South, East, and West...

Buoy or pillar placed North, East, South or West side of an obstruction to warn vessels away.

Cardinal marks indicate that the deepest water...

A type of multihulled vessel featuring two parallel hulls of equal size, connected by a deck or framework, offering stability, speed, and...

A vessel whose ability to deviate from its current course is significantly restricted due to the depth of water relative to its draught.

A...

A navigational situation where two vessels maintain the same relative bearing to each other while the distance between them diminishes, often...

The International Maritime Signal Flag Charlie.

Meaning

Affirmative.
If appended with a Numeral Pennant, a Magnetic Bearing.

Chafing is damage or wear caused by friction between two surfaces, such as ropes rubbing against a boat's railing or sails rubbing against a...

A strong metal plate, usually stainless steel, bolted to a boat’s hull or deck to which the shrouds or stays of the rigging are...

A supplier or dealer specialising in providing equipment, provisions, and supplies for ships and their crews.

A chandler refers to a...

A navigable waterway, often a natural or dredged passage, that allows vessels to travel between larger bodies of water or through shallow...

Pronounced: CHAR-lee

The term for the letter C in the NATO Phonetic Alphabet.

A detailed map used in marine navigation, showing water depths, hazards, and other critical information for safe passage.

A marine chart...

An electronic navigation device used on boats to display electronic navigation charts and track the vessel's position in real-time using GPS...

A flat, dedicated surface aboard a vessel used for spreading out nautical charts and plotting courses during navigation.

A chart table is an...

The second-in-command on a vessel, responsible for overseeing the ship's day-to-day operations, cargo handling, and the safety of the crew and...

The sharp angle or edge formed where the hull's sides meet its bottom, commonly found in hard-chined boats. 

A chine is a critical structural...

Chock-a-block is a nautical term describing when two blocks (pulleys) are pulled so close together that they cannot be tightened further. It...

A highly accurate timekeeping instrument, specifically designed for determining longitude at sea.

A chronometer is a precision timepiece used...

⚓ Nautical Origin of A Clean Bill of Health:

Back in the 18th and 19th centuries, when ships traveled from port to port, they could carry more...

Clear water is transparent and free from sediment, debris, or other particles that may obstruct visibility. This is important for snorkelling,...

Clear weather refers to atmospheric conditions free of significant cloud cover, precipitation, fog, or other weather disturbances. The sky is...

To disentangle a line, for example, removing it from a dock cleat when manoeuvring out of a marina.

When departing from a mooring, it is good...

A fitting on a boat or dock used to secure lines or ropes. Cleats typically have two horns or arms extending from a base, allowing lines to be...

This shape represents the Letter C (Flag Semaphore) and the Number 3 (Flag Semaphore).

International Morse Code sequence representing the letter C.

The lower aft corner of a sail, where the foot and leech meet, and is often equipped with a grommet or cringle for attaching control lines such...

Used primarily in maritime and aviation contexts to describe the shortest distance that will be achieved between two moving objects, such as...

A clove hitch is a versatile, easy-to-tie knot commonly used to secure a rope to a post or pole temporarily. One of its most common uses is...

A deck fitting used to grip and hold a rope or line under load while allowing for controlled release when needed. 

A clutch is a specialised...

The raised portion of a boat's deck, typically over the cabin, providing additional headroom and space below deck.

The coachroof, also known...

The organisation responsible for search and rescue operations in UK waters.

His Majesty's Coastguard (HMCG) is a section of...

The small triangular area formed when three position lines on a nautical chart intersect but do not meet at a single point, indicating a degree...

The area of a boat, typically located towards the stern, where the helm, controls, and seating for the crew are situated.

The cockpit of a...

A lightweight, high-performance sail designed for close-reaching angles, typically used in light wind conditions to maximise boat speed. 

A...

The actual path a vessel follows over the surface of the Earth, as opposed to its heading or intended course.

Course Over Ground (COG) is a...

The internationally agreed rules designed to prevent collisions at sea by setting out navigation procedures, responsibilities, and conduct for...

The internationally agreed rules designed to prevent collisions at sea by setting out navigation procedures, responsibilities, and conduct for...

Irish Lights is responsible for maintaining lighthouses, buoys, beacons, and other navigation aids along the entire coast of Ireland, including...

A companionway is a stairway or ladder that provides access between different levels on a boat or ship. It typically connects the main deck to...

A navigational instrument that determines direction relative to the Earth’s magnetic poles. It typically consists of a magnetised needle aligning...

The CADET mnemonic can help remember the corrections needed when converting between True North and Compass North bearings. It assists in...

A circular diagram on nautical charts and compasses that displays directions relative to true north and magnetic north, often including...

A navigational situation where two vessels maintain the same relative bearing to each other while the distance between them diminishes, often...

A vessel whose ability to deviate from its current course is significantly restricted due to the depth of water relative to its draught.

A...

The primary time standard by which the world regulates clocks and time serving as the basis for civil time globally.

Coordinated Universal...

The apparent deflection of moving fluids, such as air or water, caused by the Earth's rotation, influencing large-scale ocean currents and wind...

An international satellite-based search and rescue system that detects and locates distress signals from emergency beacons to assist in maritime,...

The actual path a vessel follows over the surface of the Earth, as opposed to its heading or intended course.

Course Over Ground (COG) is a...

The compass direction a vessel must follow to reach a planned destination, taking into account the effects of wind, tide, and current. It is not...

A national flag flown by a visiting vessel in foreign waters as a gesture of respect to the host country.

A courtesy ensign is a flag flown by...

Used primarily in maritime and aviation contexts to describe the shortest distance that will be achieved between two moving objects, such as...

The group of individuals who work together on a vessel or ship to operate, maintain, and navigate it. Depending on the type and size of the...

A cringle is a small metal ring or grommet typically sewn into a sail to provide a point for attaching lines or other rigging. Cringles reinforce...

Sea area of the Met Office Shipping Forecast. Lies off the east coast of Scotland, near the mouth of the Cromarty Firth.

Taking its name from...

The lateral distance and drift between a vessel's actual position and the intended navigational track or course.

Cross Track Error (XTE) is a...

The compass direction a vessel must follow to reach a planned destination, taking into account the effects of wind, tide, and current. It is not...

The continuous, directed movement of seawater or other bodies of water caused by various factors such as wind, tides, and differences in water...

A cyclone is a large-scale atmospheric circulation system characterised by inward-spiralling winds around a low-pressure centre. In marine...

Cyclonic refers to a weather system characterised by air rotation around a low-pressure centre, typically in a counterclockwise direction in the...