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      All our courses are engaging, interactive and fun! Whether formal training or simply looking to brush up, we take online learning to the next level.

      • Sailing EssentialsFreeA free course great for anyone who spends time on the water.
      • Essential Navigation & SeamanshipRYA course for beginners. Learn charts, tides, pilotage, and core seamanship with simple practice tasks.
      • Day Skipper TheoryMost PopularRYA course for inshore skippers. Plan day passages using chartwork, tides, weather, and COLREGs.
      • Coastal Skipper / Yachtmaster® TheoryComing SoonRYA course for advanced navigation and passage planning. Work with secondary ports, tidal streams, and offshore weather.
      • SRC (VHF) Marine Radio CourseRYA Short Range Certificate radio course. Study online, then take the practical exam with an RYA assessor.
  • Directory

      Are you looking for something nautical related? Our directory is an extensive list of courses and places associated with the marine industry. Hop over and search now.

      • Places
        Find anywhere nautical, including marinas & training centres. If it exists, we’ve got it listed!
      • Courses
        We help you navigate through the complex world of training and help find what’s best for you.
  • Know-How

      We believe every day’s a school day on a boat! That’s why we built Nautical Know-How, dedicated to answering your questions. Even better, if it can’t answer your question immediately, you can request it, and we’ll add it to our knowledge base.

      • Nautical Terms & Terminology
        Understanding the language of the marine world is like trying to learn a pirate’s secret code while juggling fish. Let us explain why a sheet isn’t for your bed, why “heave ho” doesn’t mean throw up (most of the time), and why “dead reckoning” is surprisingly less ominous than it sounds.
      • Why do we have tides?
        Have you ever wondered what causes the tides? Check out this video, which introduces the forces that create the tides we experience on Earth.
      • What causes our weather?
        A video introducing the drivers behind our weather, part of our RYA Day Skipper & RYA Coastal Skipper / Yachtmaster® Offshore theory courses.
      • Buoyage Flashcards
        Flashcards designed to help remember the buoys in the IALA system. If you want to learn them in detail, our module ‘Getting in and out of harbour‘, covers the IALA system and different buoys used.
      • Interactive Rule Book (COLREGs / IRPCS)
        Whether you’re a novice sailor or a seasoned skipper, we can help you navigate the IRPCS confidently and clearly. Our easy-to-use, easy-to-understand, plain English rule book with helpful interpretations of what each rule means.
      • The Salty Sea Blog
        From salty old sea dogs to fresh-faced deckhands, this blog is for anyone who finds peace, adventure, and a bit of mischief on the water. So hoist the main, set your course, and let’s sail into the stories, lessons, and musings that make life on the sea so irresistible.
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Nautical Know How
  • Our Courses

      All our courses are engaging, interactive and fun! Whether formal training or simply looking to brush up, we take online learning to the next level.

      • Sailing EssentialsFreeA free course great for anyone who spends time on the water.
      • Essential Navigation & SeamanshipRYA course for beginners. Learn charts, tides, pilotage, and core seamanship with simple practice tasks.
      • Day Skipper TheoryMost PopularRYA course for inshore skippers. Plan day passages using chartwork, tides, weather, and COLREGs.
      • Coastal Skipper / Yachtmaster® TheoryComing SoonRYA course for advanced navigation and passage planning. Work with secondary ports, tidal streams, and offshore weather.
      • SRC (VHF) Marine Radio CourseRYA Short Range Certificate radio course. Study online, then take the practical exam with an RYA assessor.
  • Directory

      Are you looking for something nautical related? Our directory is an extensive list of courses and places associated with the marine industry. Hop over and search now.

      • Places
        Find anywhere nautical, including marinas & training centres. If it exists, we’ve got it listed!
      • Courses
        We help you navigate through the complex world of training and help find what’s best for you.
  • Know-How

      We believe every day’s a school day on a boat! That’s why we built Nautical Know-How, dedicated to answering your questions. Even better, if it can’t answer your question immediately, you can request it, and we’ll add it to our knowledge base.

      • Nautical Terms & Terminology
        Understanding the language of the marine world is like trying to learn a pirate’s secret code while juggling fish. Let us explain why a sheet isn’t for your bed, why “heave ho” doesn’t mean throw up (most of the time), and why “dead reckoning” is surprisingly less ominous than it sounds.
      • Why do we have tides?
        Have you ever wondered what causes the tides? Check out this video, which introduces the forces that create the tides we experience on Earth.
      • What causes our weather?
        A video introducing the drivers behind our weather, part of our RYA Day Skipper & RYA Coastal Skipper / Yachtmaster® Offshore theory courses.
      • Buoyage Flashcards
        Flashcards designed to help remember the buoys in the IALA system. If you want to learn them in detail, our module ‘Getting in and out of harbour‘, covers the IALA system and different buoys used.
      • Interactive Rule Book (COLREGs / IRPCS)
        Whether you’re a novice sailor or a seasoned skipper, we can help you navigate the IRPCS confidently and clearly. Our easy-to-use, easy-to-understand, plain English rule book with helpful interpretations of what each rule means.
      • The Salty Sea Blog
        From salty old sea dogs to fresh-faced deckhands, this blog is for anyone who finds peace, adventure, and a bit of mischief on the water. So hoist the main, set your course, and let’s sail into the stories, lessons, and musings that make life on the sea so irresistible.
  • Chandlery
Sign In Join now—it’s Free

Glossary

Nautical chart abbreviations are like the secret code of the seas—except instead of buried treasure, they lead to rocks, buoys, and mysterious dashed lines that scream, 'Don’t sail here.' Learning them can feel like cracking a pirate’s encrypted diary, but don’t worry, matey! With clever tools, quirky mnemonics, and a splash of humour, we’ll help you go from 'What’s "FOUL" mean? to confidently navigating the “Wk” wrecks and “Fl G” flashes like a salty sea captain. Think of it as Rosetta Stone, but for avoiding sandbanks!
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Results: 67
  • Term
    Definition
  • General Nautical Terminology, Safety Danbuoy

    A floating marker pole, often equipped with a flag, light, or buoyancy aid, used in maritime settings to indicate a specific location, such...

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  • General Nautical Terminology Danforth Anchor

    A lightweight, high-holding-power anchor with two wide, pivoting flukes designed to dig into sand or mud for secure holding. 

    The Danforth...

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  • General Nautical Terminology Davit

    Crane-like structures mounted on a vessel used for lowering, raising, and storing lifeboats, tenders, or other equipment. 

    Davits are...

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  • General Nautical Terminology Day Shape

    A ball, cone or diamond-shaped object, ordinarily black, hoisted by day on a vessel to indicate a particular status within the IRPCS. 

    If you...

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  • Courses, RYA Day Skipper Practical (Motor)The RYA Day Skipper Practical (Motor) course equips participants to take charge of motor cruisers during short passages. Over five days,... More Details
  • Courses, RYA Day Skipper Practical (Sail)

    The RYA Day Skipper Practical (Sail) course teaches participants to skipper a yacht during short coastal passages. This five-day course covers...

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  • Courses, RYA Day Skipper TheoryThe RYA Day Skipper Theory course provides aspiring skippers with the knowledge to navigate safely in coastal waters. This comprehensive program... More Details
  • Flag / Pennant, Signals & Communication Code Flag Delta (D)

    The International Maritime Signal Flag Delta.

    Meaning

    I am manoeuvring with difficulty.
    If appended with a Numeral Pennant, a Date.

  • General Nautical Terminology, Navigation Dead Reckoning (DR)

    A navigational method used to estimate a vessel's current position based on a previously known position, factoring in speed, time, and course...

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  • General Nautical Terminology Deck Officer

    A licensed mariner responsible for the safe navigation, operation, and management of a vessel's deck department.

    Deck Officers, also known as...

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  • Phonetic Alphabet, Signals & Communication Delta

    Pronounced: DEL-ta

    The term for the letter D in the NATO Phonetic Alphabet.

  • General Nautical Terminology Delta

    A triangular-shaped area of sediment deposited at the mouth of a river, where it meets a body of water such as a sea or ocean.

    A delta refers...

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  • General Nautical Terminology Delta Anchor

    A plough-style anchor with a triangular, streamlined shape, designed for strong holding power in various seabeds, especially sand and mud.

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  • General Nautical Terminology Depression

    A depression is an area of low atmospheric pressure characterised by inward-spiraling winds. Depressions are often associated with stormy weather...

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  • General Nautical Terminology DepthAn electronic depth-finding instrument or the amount of water at a given time
  • General Nautical Terminology, Navigation Deviation

    The difference between a vessel's actual compass heading and the magnetic heading indicated by the compass.

    Deviation is caused by the...

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  • General Nautical Terminology, Navigation Deviation card

    A reference chart used on a vessel to indicate the compass error caused by local magnetic influences, showing the necessary corrections for...

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  • General Nautical Terminology DiaphoneA powerful two-tone fog signal with a grunt at the end.
  • Courses, RYA Diesel EngineThe RYA Diesel Engine course is a one-day program designed for boat owners and operators who want to maintain and troubleshoot their engines... More Details
  • General Nautical Terminology Digital Selective CallingIs the process of sending a digital message using a VHF transmission. It is used to send and listen for distress signals in maritime situations... More Details
  • General Nautical Terminology, Safety, Signals & Communication Digital Selective Calling (DSC)

    An automated VHF and MF/HF radio communication system used in maritime environments to send distress alerts, establish contact, and exchange...

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  • General Nautical Terminology, Navigation Dilution of Precision (DOP)

    Used in satellite navigation and geolocation to provide the likely accuracy of a satellite-derived position.

    The DOP concept is essential to...

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  • General Nautical Terminology DinghyA type of small boat, often carried or towed as a ship’s boat by a larger vessel. Also small open sailing boats often used for racing and training
  • Courses, RYA Dinghy Club RacingThe RYA Dinghy Club Racing course prepares sailors to participate confidently in local club races. The course covers essential skills such as... More Details
  • Courses, RYA Dinghy Day SailingThe RYA Dinghy Day Sailing course equips sailors with the knowledge and skills to plan and execute safe and enjoyable day trips. The course... More Details
  • Courses, RYA Dinghy Foiling First FlightsThe RYA Dinghy Foiling First Flights course provides an introduction to the exhilarating world of foiling. Designed for experienced sailors, this... More Details
  • Courses, RYA Dinghy Foiling Performance FlightsBuilding on the basics, the RYA Dinghy Foiling Performance Flights course refines foiling skills for greater control and speed. Participants... More Details
  • Courses, RYA Dinghy Foiling Sustained FlightsThe RYA Dinghy Foiling Sustained Flights course is for experienced sailors aiming to master continuous foiling. Participants focus on fine-tuning... More Details
  • Courses, RYA Dinghy Level 1 - Start SailingThe RYA Dinghy Level 1 course is an introductory program for beginners learning the fundamentals of sailing. Participants practice rigging,... More Details
  • Courses, RYA Dinghy Level 2 - Basic SkillsThe RYA Dinghy Level 2 course builds on the foundation of Level 1, teaching participants to sail independently. Sailors practice tacking, gybing,... More Details
  • Courses, RYA Dinghy Level 3 - Better SailingThe RYA Dinghy Level 3 course focuses on refining sailing techniques and building confidence in more challenging conditions. Participants enhance... More Details
  • Courses, RYA Dinghy Performance SailingThe RYA Dinghy Performance Sailing course is designed for experienced sailors aiming to enhance their racing and technical skills. This advanced... More Details
  • Courses, RYA Dinghy Regional RacingThe RYA Dinghy Regional Racing course is designed for sailors transitioning to competitive racing at a regional level. Participants learn advanced... More Details
  • Courses, RYA Dinghy Sailing with SpinnakersThe RYA Dinghy Sailing with Spinnakers course introduces sailors to the exciting challenge of spinnaker handling. Participants learn how to rig,... More Details
  • Courses, RYA Dinghy Seamanship SkillsThe RYA Dinghy Seamanship Skills course focuses on developing practical abilities to handle dinghies in a variety of conditions. Participants... More Details
  • Courses, RYA Dinghy Start RacingThe RYA Dinghy Start Racing course is perfect for sailors looking to begin their journey into competitive sailing. This course covers racing... More Details
  • General Nautical Terminology Dip the EnsignTo lower the ensign briefly as a salute.  It is not re-hoisted until the vessel saluted has dipped and re-hoisted hers in acknowledgement
  • General Nautical Terminology Directional LightA light illuminating a sector or very narrow angle and intended to mark a direction to be followed.
  • General Nautical Terminology, Navigation Direction of Buoyage

    The direction in which lateral marks (port and starboard buoys) should be passed when entering a harbour or following a main channel, based on...

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  • General Nautical Terminology, Parts of a Boat Displacement

    The weight of the water a vessel displaces when it is floating, which is equal to the vessel's own weight.

    Displacement is a fundamental...

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  • General Nautical Terminology, Parts of a Boat Displacement Vessel

    A type of watercraft designed to move through the water by displacing an amount of water equal to its own weight, relying on buoyancy and...

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  • General Nautical Terminology Distance

    The length of space between two points, often measured in nautical miles when referring to distances at sea.

    In maritime contexts, "distance"...

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  • General Nautical Terminology, Navigation Distance to Waypoint (DTW)

    The measured distance, typically in nautical miles, between a vessel's current position and a predetermined navigational point or...

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  • General Nautical Terminology, Navigation Dividers

    A navigational tool consisting of two hinged legs with pointed ends, used by mariners to measure distances on a nautical chart.

    Dividers...

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  • Flag Semaphore, Signals & Communication Letter D (Flag Semaphore)
    Letter D (Flag Semaphore)

    This shape represents the Letter D (Flag Semaphore) and the Number 4 (Flag Semaphore).

  • Morse Code, Signals & Communication Letter D (Morse Code)

    International Morse Code sequence representing the letter D.

  • General Nautical Terminology DodgerScreen fitted to give the crew protection from wind and spray
  • General Nautical Terminology, Weather (Meteorology) Dogger

    Sea area of the Met Office Shipping Forecast. Spans Dogger Bank in the central North Sea, between the UK and continental Europe.

    Named after...

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  • General Nautical Terminology Dog Watch


    A shortened watch period aboard a vessel, typically divided into two shifts from 16:00 to 18:00 and 18:00 to 20:00, to allow for a rotation of...

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  • General Nautical Terminology DolphinA mooring post or group of piles
  • General Nautical Terminology, Navigation DOP

    Used in satellite navigation and geolocation to provide the likely accuracy of a satellite-derived position.

    The DOP concept is essential to...

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  • General Nautical Terminology Double UpTo put out extra mooring lines when a storm is expected
  • General Nautical Terminology DouseTo lower a sail; To extinguish a light quickly
  • General Nautical Terminology, Weather (Meteorology) Dover

    Sea area of the Met Office Shipping Forecast. Spans the English Channel at the Strait of Dover between England and France.

    Named after the port...

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  • General Nautical Terminology, Parts of a Boat Downhaul

    A downhaul is a line or tackle to apply downward tension on a sail or spar to control its shape and optimise performance.

    The downhaul is an...

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  • General Nautical Terminology DownstreamThe direction towards which the stream flows
  • General Nautical Terminology Downwind

    Refers to the direction in which the wind is blowing relative to a specific point of reference.

    When sailing or navigating on the water,...

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  • General Nautical Terminology, Navigation DR

    A navigational method used to estimate a vessel's current position based on a previously known position, factoring in speed, time, and course...

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  • General Nautical Terminology DragThe anchor drags when it fails to hold and slides over the seabed
  • General Nautical Terminology Draught

    The vertical distance between the waterline and the lowest point of the hull, typically the keel, indicating how deep the vessel sits in the...

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  • General Nautical Terminology DredgerA vessel for dredging a channel
  • General Nautical Terminology Drift

    To be carried along by currents or wind without a set course or direction. The movement of a vessel or object caused by wind, currents, or tides,...

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  • General Nautical Terminology Drogue

    A device, often resembling a small parachute or cone, deployed from a vessel or lifeboat to create drag and stabilise its movement in rough...

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  • General Nautical Terminology Drying Height

    The vertical distance between the seabed or a drying feature, such as a rock or sandbank, and chart datum, which is usually lowest astronomical...

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  • General Nautical Terminology, Safety, Signals & Communication DSC

    An automated VHF and MF/HF radio communication system used in maritime environments to send distress alerts, establish contact, and exchange...

    More Details
  • General Nautical Terminology, Navigation DTW

    The measured distance, typically in nautical miles, between a vessel's current position and a predetermined navigational point or...

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  • General Nautical Terminology Dyneema

    A high-performance synthetic fibre known for its exceptional strength-to-weight ratio.

    It is often used in marine applications for rigging,...

    More Details

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