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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
  • Courses, RYA Marine Radio VHF (SRC)The RYA Marine Radio VHF (SRC) course is a mandatory qualification for anyone operating a marine VHF radio with Digital Selective Calling (DSC).... More Details
  • Organisation Maritime and Coastguard Agency (MCA)

    The Maritime and Coastguard Agency (MCA) is a UK government agency responsible for implementing maritime safety and environmental policies. It...

    More Details
  • General Nautical Terminology, Safety Maritime Mobile Service Identity (MMSI)

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

    More Details
  • General Nautical Terminology Maritime Rescue Coordination Centre (MRCC)

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

    More Details
  • General Nautical Terminology, Navigation Maritime Safety Information

    Defined in the Safety of Life at Sea (SOLAS) Convention, Chapter IV as "navigational and meteorological warnings, meteorological forecasts and...

    More Details
  • General Nautical Terminology MARPOL

    Established by the IMO, MARPOL is the convention for preventing pollution from ships. It is the main international convention covering the...

    More Details
  • General Nautical Terminology Mast

    A tall vertical spar or structure on a sailing vessel that supports the sails, rigging, and sometimes navigation equipment.

    A mast is one of...

    More Details
  • General Nautical Terminology Masthead light

    A white, forward facing light exhibited near the masthead by a power-driven vessel underway.

  • General Nautical Terminology Mast StepFitting into which the mast heel fits
  • General Nautical Terminology, Safety, Signals & Communication MayDay

    An internationally recognised distress signal used in voice communication to indicate a grave or imminent, life-threatening emergency at...

    More Details
  • Organisation MCA

    The Maritime and Coastguard Agency (MCA) is a UK government agency responsible for implementing maritime safety and environmental policies. It...

    More Details
  • Flag / Pennant, Signals & Communication Code Flag Mike (M)

    The International Maritime Signal Flag Mike.

    Meaning

    My vessel is stopped and making no way through the water.

  • Abbreviation, General Nautical Terminology, Navigation Mean High Water Neaps (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 Mean High Water Springs (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
  • Abbreviation, General Nautical Terminology, Navigation Mean Low Water Neaps (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 Mean Low Water Springs (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 MEDILINK

    A communication made via radio from a vessel to a shore-based medical facility or professional to seek urgent medical advice or assistance for an...

    More Details
  • General Nautical Terminology, Signals & Communication Medium Frequency (MF)

    The range of radio frequencies between 300 kHz and 3 MHz, commonly used in marine communication and navigation systems.

    Medium Frequency (MF)...

    More Details
  • General Nautical Terminology, Organisation, Weather (Meteorology) Met Office

    The United Kingdom's national meteorological service, responsible for providing weather and climate-related services, including marine...

    More Details
  • General Nautical Terminology, Signals & Communication MF

    The range of radio frequencies between 300 kHz and 3 MHz, commonly used in marine communication and navigation systems.

    Medium Frequency (MF)...

    More Details
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