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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.
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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

AJAX progress indicator
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: 1149
  • Term
    Definition
  • 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...

    More Details
  • 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,...

    More Details
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