Glossary Archive

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 onboard medical emergency. A Radio Medical Advice Link Call is an essential protocol in maritime operations, particularly for vessels operating far from shore where immediate access to medical facilities is unavailable....

Two or more vessels tied up alongside each other

The vertical difference between the high tide and the succeeding low tide in a specific tidal cycle. The range of tide is a fundamental concept in marine navigation and coastal activities, describing the extent of tidal fluctuation at a given location. It is calculated by measuring the vertical distance between the highest water level (high...

Electronic chart which is a direct copy of a paper chart with limited zooming capability

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 to tidal forces, usually expressed in knots (nautical miles per hour). Tidal streams are horizontal movements of water caused by the rise and fall of the tide, and...

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 refers to a specific point of sail where the wind is coming from the side of the boat, typically at an angle between 90° and 135° relative to the...

Sailing across the wind: from about 60° to about 160° off the wind. Reaching consists of "close reaching" (about 60° to 80°), "beam reaching" (about 90°) and "broad reaching" (about 120° to 160°).

The helmsman’s shout that he intends to go about shortly

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 (Flag Semaphore).