Glossary

A passive device designed to enhance a vessel's visibility on radar systems by reflecting radar signals back to their source.

A radar...

A communication made via radio from a vessel to a shore-based medical facility or professional to seek urgent medical advice or assistance for an...

A ship that, due to the nature of its work, is unable to keep out of the way of other vessels as required by the International Regulations for...

The vertical difference between the high tide and the succeeding low tide in a specific tidal cycle.

The range of tide is a fundamental...

The speed at which a tidal stream flows, typically measured in knots.

The rate of a tidal stream is the velocity at which the water moves due...

The International Maritime Signal Flag Romeo.

Meaning

Distance (range) in nautical miles. Given using Numeral Pennants.

The point of sail where the wind is coming from the side of the boat, roughly perpendicular to the direction the boat is travelling. 

A reach...

The Ready (Flag Semaphore) signal shows the sender is ready to send a message. The same shape is also used for Space (Flag Semaphore) & Rest...

The Ready to Recieve signal shows the sender that the recipient is ready to receive a message. This shape is displayed once the sender has...

A reef is a submerged ridge of rock, coral, or sand near the surface of oceans or seas. It can be made up of living organisms like coral or...

The act of reducing the area of a sail to decrease wind exposure and maintain control in strong winds.

Reefing is an essential technique in...

A reefing hook is located near the bottom of the mast at the gooseneck, where the boom connects to the mast. When reefing, the cringle is placed...

Ropes or cords used to reduce the sail area by securing a portion of the sail to the boom or mast, thereby making the vessel more manageable in...

When the sender is not actively sending messages, both flags are held by their side. The same shape is also used for Space (Flag Semaphore) &...

A ship that, due to the nature of its work, is unable to keep out of the way of other vessels as required by the International Regulations for...

Conditions in which a vessel's ability to see is significantly reduced due to environmental factors such as fog, heavy rain, snow, or...

A loop of rope that crosses over itself on a winch drum or cleat, often causing friction or jamming.

A riding turn is a term commonly used in...

The system of ropes, cables, chains, and other apparatus used to support and control the sails and masts of a sailing vessel.

Rigging is...

Verb - The process of setting up and adjusting the sails, lines, and other necessary equipment on a boat or ship to ensure it is ready for...

An internationally renowned professional institution representing naval architects and marine engineers worldwide. It was founded in 1860 and is...

The possibility that a collision may occur, usually established by taking a compass bearing of an approaching vessel. Defined in Rule 7 - Risk of...

Flag semaphore indicating the letter R.

International Morse Code sequence representing the letter R.

The volunteer crewed rescue service providing 24-hour rescue services around the UK and Irish coastline. They also provide seasonal lifeguards...

Sea area of the Met Office Shipping Forecast. Spans the North Atlantic west of Ireland around Rockall islet.

Named for the remote granite islet...

The line, chain, or cable that connects an anchor to a vessel.

Rode refers to the length of chain, rope, or a combination of both that...

Roller furling is used on sailing boats to roll or unroll a sail, typically the jib or genoa, around a stay to quickly deploy or stow the...

A roller reef is a method of reducing sail area on a sailboat by partially rolling or furling the sail around the boom or the headstay. This...

Pronounced: ROW-me-oh

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

A spare fender, held ready by a crew member in case of emergencies.

A roving fender is a type of fender used on boats and ships to protect the...

The volunteer crewed rescue service providing 24-hour rescue services around the UK and Irish coastline. They also provide seasonal lifeguards...

The national governing body for sailing, motorboating, and other recreational boating activities in the United Kingdom. 

The Royal Yachting...

A rudder is a flat, movable surface attached to the stern of a boat or ship. It is used to steer the vessel by redirecting water flow.

The...

To allow a line, rope, or cable to move freely through a block, fairlead, or other fitting.

The direction a vessel is moving, particularly...

The act of sailing a boat downwind, with the wind coming from astern. 

Running is one of the main points of sail, where a vessel moves with...

A rigging component on a sailboat that helps support the mast. It runs from each lateral corner of the stern to the mast at the level where the...

The ropes, lines, and cables that control a sailing vessel’s sails and other movable components.

Running rigging is a critical part of a...

The national governing body for sailing, motorboating, and other recreational boating activities in the United Kingdom. 

The Royal Yachting...

A lightweight Plotter, suitable for use in a classroom for navigation exercises.

This handy size plotter has been specifically designed to...

Publication compiled to support RYA Theory courses. The RYA Training Almanac contains exerts that mimic Nautical Almanacs in the real world.

A specialised, non-navigational chart produced by the Royal Yachting Association (RYA) for teaching and practising navigation and chartwork...