Glossary
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TermDefinition
- General Nautical Terminology RaceA strong tidal stream
- Courses RadarThe RYA Radar course teaches participants to use radar systems effectively for navigation and collision avoidance. Topics include radar setup,... More Details
- General Nautical Terminology, Safety Radar Reflector
A passive device designed to enhance a vessel's visibility on radar systems by reflecting radar signals back to their source.
A radar...
More Details - General Nautical Terminology, Safety Radio Medical Advice Link Call (MEDILINK)
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...
More Details - General Nautical Terminology RaftTwo or more vessels tied up alongside each other
- Abbreviation, General Nautical Terminology RAM
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...
More Details - General Nautical Terminology, Navigation Range of Tide
The vertical difference between the high tide and the succeeding low tide in a specific tidal cycle.
The range of tide is a fundamental...
More Details - General Nautical Terminology Raster chartElectronic chart which is a direct copy of a paper chart with limited zooming capability
- General Nautical Terminology, Navigation Rate (Tidal Stream)
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...
More Details - Flag / Pennant, Signals & Communication Code Flag Romeo (R)

The International Maritime Signal Flag Romeo.
Meaning
Distance (range) in nautical miles. Given using Numeral Pennants.
- General Nautical Terminology Reach
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...
More Details - General Nautical Terminology ReachingSailing across the wind: from about 60° to about 160° off the wind. Reaching consists of "close reaching" (about 60° to 80°), "beam reaching"... More Details
- General Nautical Terminology Ready AboutThe helmsman’s shout that he intends to go about shortly
- Flag Semaphore Ready (Flag Semaphore)

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...
More Details - Flag Semaphore Ready to Recieve (Flag Semaphore)

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...
More Details - General Nautical Terminology Reef
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...
More Details - General Nautical Terminology Reefing
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...
More Details - General Nautical Terminology Reefing Hook
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...
More Details - General Nautical Terminology, Parts of a Boat Reefing Lines
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...
More Details - Flag Semaphore Rest (Flag Semaphore)

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) &...
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