Glossary Archive

Pronounced: pah-pah The term for the letter P in the NATO Phonetic Alphabet.

A pyrotechnic distress signal that, when launched, ascends to a high altitude before deploying a parachute to slow its descent while emitting a bright, long-lasting light.  A parachute flare is an essential piece of safety equipment used in marine environments to signal distress and attract attention over long distances, particularly at night or in poor...

Navigational instrument used in conjunction with the compass rose on the chart to transfer bearings and courses to plot a vessel’s position

A journey or route taken by a vessel from one location to another, often across open water or between specific points such as harbours or islands. A passage in maritime terms typically refers to the act of travelling by sea from one point to another. This could involve crossing an ocean, navigating coastal waters, or...

A detailed, structured navigational strategy outlining the safest and most efficient route for a vessel from departure to destination, considering hazards, weather, tides, and regulations.  A passage plan is essential for safe navigation and is a fundamental part of voyage planning. It ensures that all aspects of a journey are considered before departure, reducing risks...

The action or process of a vessel's bow turning away from the wind, often due to wind or rudder adjustments. When a vessel "pays off," it is essentially turning its bow away from the wind direction. This can happen due to intentional steering actions by the helmsman or as a result of external forces such...

Letting a rope, line or cable run out under control. This is used when deploying an anchor rode, easing a mooring line, setting a tow, or allowing a control line to lengthen. The key point is control, because a line running out too fast can snatch, tangle or injure hands. Crew should keep clear of...

The International Maritime Signal Flag Papa. Meaning The Blue Peter.In harbour: All persons should report on board as the vessel is about to proceed to sea.At sea: It may be used by fishing vessels to mean: My nets have come fast upon an obstruction.

Measurement of the geometric strength of satellite configuration in a Global Navigation Satellite System (GNSS) receiver. It quantifies the effect of satellite geometry on the accuracy of the position calculation. A lower PDOP value indicates better satellite geometry and results in more accurate position fixes. PDOP is calculated based on the positions of the satellites...

The small, gentle ripples or wavelets that form on the surface of the water, typically caused by light winds or minor disturbances. Perling describes a subtle surface condition of water, characterised by fine, delicate ripples that often appear when a light breeze moves across calm seas or sheltered waters. These small wavelets are usually uniform...