Glossary Archive

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 Preventing Collisions at Sea (COLREGs). A vessel classified as "Restricted in Ability to Manoeuvre" (RAM) is one that cannot deviate from its course or alter its movements...

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).

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 used the Attention (Flag Semaphore) signal before starting the communication.