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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.
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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
  • Abbreviation, General Nautical Terminology, Navigation MHWN

    The average height of high tides during neap tide cycles, which occur when the tidal range is at its smallest.

    Mean High Water Neaps (MHWN) is...

    More Details
  • Abbreviation, General Nautical Terminology, Navigation MHWS

    The average height of the high waters that occur during spring tides, calculated over a specific period of time.

    Mean High Water Springs...

    More Details
  • Phonetic Alphabet, Signals & Communication Mike

    Pronounced: MIKE

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

  • General Nautical Terminology MistVisibility reduced to between 0.5 and 2 nautical miles due to suspension of water particles in the air
  • General Nautical Terminology, Weather (Meteorology) Mistral

    A strong, cold, and dry northwesterly katabatic wind that blows from southern France into the Mediterranean, particularly affecting the Gulf of...

    More Details
  • General Nautical Terminology Mizzen MastMast aft of the mainmast, on a ship.
  • Flag Semaphore, Signals & Communication Letter M (Flag Semaphore)
    Letter M (Flag Semaphore)

    Flag semaphore indicating the letter M.

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

    International Morse Code sequence representing the letter M.

  • Abbreviation, General Nautical Terminology, Navigation MLWN

    The average height of low tides during neap tide cycles, which occur when the tidal range is at its smallest due to the reduced gravitational...

    More Details
  • Abbreviation, General Nautical Terminology, Navigation MLWS

    The average level of the lowest low tides that occur during spring tide conditions, calculated over a standard period of time.

    Mean Low Water...

    More Details
  • General Nautical Terminology, Safety MMSI

    A unique nine-digit number assigned to a vessel, coast station, or group of stations for digital communication and identification in the Global...

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  • General Nautical Terminology Mole

    A solid structure, often made of stone or concrete, built to protect a harbour, anchorage, or shoreline from the effects of waves and currents,...

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  • General Nautical Terminology MonohullA vessel with a single hull
  • General Nautical Terminology Mooring

    A permanent structure or equipment, such as a buoy, anchor, or dock, used to secure a vessel in place or the act of securing a vessel to a fixed...

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  • General Nautical Terminology Mooring Buoy

    A non-navigational floating device anchored to the seabed, used for securing vessels in place without the need for traditional anchoring.

    A...

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  • General Nautical Terminology Mooring RingA ring on a mooring buoy
  • General Nautical Terminology Motor sailing

    A sailing vessel making way using sails and engine. A downward pointing cone should be displayed in the fore triangle in daylight and lights for...

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  • General Nautical Terminology MRCC

    A shore-based facility responsible for coordinating and managing maritime search and rescue (SAR) operations within a designated area of...

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  • Courses, RYA Multihull Club RacingThe RYA Multihull Club Racing course prepares sailors to participate in local club races with confidence. The course covers race rules, starting... More Details
  • Courses, RYA Multihull Day SailingThe RYA Multihull Day Sailing course prepares sailors to undertake safe and enjoyable day trips on multihulls. Participants learn about trip... More Details
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