Royal National Lifeboat Institution (RNLI) (RNLI)
The volunteer crewed rescue service providing 24-hour services around the UK and Irish coastline. They also provide seasonal lifeguards who look after people on busy beaches.
Safety
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General Nautical Terminology | Nautical Topics | Navigation | Parts of a Boat | Safety | Signals & Communication
Electronic Chart Display and Information System (ECDIS) (ECDIS)
A type-approved shipborne navigation system meeting IMO performance standards for displaying official electronic chart data and supporting route planning and monitoring. With adequate backup arrangements and up-to-date official chart data, ECDIS can satisfy applicable SOLAS chart-carriage requirements. It integrates position and other sensor information with chart objects, safety contours, route checks, alarms and official updates….
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Closest Point of Approach (CPA)
The predicted minimum distance between two moving targets if both maintain their present course and speed. Commonly abbreviated to CPA, it is calculated from relative motion and is normally considered with Time to Closest Point of Approach, or TCPA. Radar, AIS and plotting systems can display these values to support assessment of an approaching vessel….
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Time to Closest Point of Approach (TCPA) (TCPA)
The predicted time remaining until two moving objects reach their calculated closest point of approach if their motions remain unchanged. TCPA is derived with closest point of approach from relative position and velocity, using radar plotting, ARPA, AIS or other tracking. A positive value normally indicates the CPA is ahead in time; a negative value…
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Pilotage
Detailed navigation in confined, coastal or harbour waters using a pre-planned sequence of references, limits and actions. A pilotage plan can use visual marks, transits, clearing bearings, soundings, radar ranges, GNSS positions, buoyage, tidal windows, courses, speeds and abort points. It is prepared at a scale and tempo that supports continuous monitoring as hazards and…
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Sailing Directions
Official or authoritative publications giving descriptive navigation information that supplements nautical charts. They can describe coast and harbour approaches, hazards, currents, climate, routeing, regulations, reporting, pilotage, facilities and local procedures that cannot be shown fully on a chart. Hydrographic offices issue regional volumes under names such as Sailing Directions or Pilots. The correct volume, edition,…
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Passage (Voyage)
A voyage or distinct navigational leg made by a vessel between defined places or operational stages. A passage can be coastal, offshore, inland or between nearby berths and need not cross open water. It is commonly supported by a passage plan covering appraisal, planning, execution and monitoring from berth to berth or through another clearly…
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Victualling
Provisioning a vessel with food, drink and related consumable stores for its voyage and occupants. The task includes estimating quantities, dietary and medical needs, potable water, cooking fuel, storage life, refrigeration and waste, with reserves for delay or emergency. It can also include managing inventory and rotation during the voyage. Weight, stowage, ventilation, pest control,…
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Compass Deviation Card
A vessel-specific table or graph showing magnetic-compass deviation for a range of headings. Deviation is the angular error caused by the vessel’s own magnetic fields and is determined by swinging the compass and comparing known headings or bearings. The card records east or west corrections, often with separate values for principal and intercardinal headings and…
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Constant Bearing, Decreasing Range (CBDR) (CBDR)
A collision-warning condition in which another object’s bearing remains nearly steady while its distance decreases. If two vessels continue with unchanged velocity, a steady relative bearing and closing range indicate that their tracks lead to the same point at approximately the same time. Repeated visual bearings, radar plotting or reliable relative-motion data can reveal the…
If you belive the Earth is flat, you're about to fall of the end...
If you belive the Earth is flat, you're about to fall of the end...
