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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 & SeamanshipA great introduction to navigation and basic seamanship.
    • Day Skipper TheoryMany of the best skippers started their journey here.
    • Coastal Skipper / Yachtmaster® TheoryComing SoonEssential preparation for the Yachtmaster® practical exam.
    • SRC (VHF) Marine Radio CourseAn essential course for anyone intending to use a marine radio.
  • 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 nauctical, including marinas u0026 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 u0026 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 & SeamanshipA great introduction to navigation and basic seamanship.
    • Day Skipper TheoryMany of the best skippers started their journey here.
    • Coastal Skipper / Yachtmaster® TheoryComing SoonEssential preparation for the Yachtmaster® practical exam.
    • SRC (VHF) Marine Radio CourseAn essential course for anyone intending to use a marine radio.
  • 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 nauctical, including marinas u0026 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 u0026 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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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: 1071
  • Term
    Definition
  • General Nautical Terminology, Navigation Horizontal Dilution of Precision (HDOP)

    Used in satellite navigation and positioning systems to quantify the accuracy of horizontal position measurements. It is a unitless factor that...

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  • General Nautical Terminology, Safety Horseshoe Lifebuoy

    A U-shaped flotation device designed to be thrown to a person overboard to provide buoyancy and aid in rescue.

    The horseshoe lifebuoy, also...

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  • Phonetic Alphabet, Signals & Communication Hotel

    Pronounced: hoh-TELL

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

  • General Nautical Terminology HoundsAttachments of stays to masts.
  • General Nautical Terminology House flagAny personal flag or club flag flown from starboard spreaders or flagstaff.
  • General Nautical Terminology Hull

    The watertight body or shell of a boat or ship, excluding the deck, rigging, and other superstructures.

    The hull is the fundamental structure...

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  • General Nautical Terminology Hull SpeedThe maximum efficient speed of a displacement-hulled vessel.
  • General Nautical Terminology, Weather (Meteorology) Hurricane Force

    Beaufort Scale - Force 12 (Hurricane Force 12)

    Hurricane-force is a term used to describe wind speeds equal to or greater than 64 knots (74...

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  • General Nautical Terminology Hydrofoil

    A lifting surface or structure mounted beneath a vessel's hull that, when moving through water, generates lift to raise the hull above the...

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  • General Nautical Terminology HydrographyThe science of surveying the waters of the earth and adjacent land area, and publishing the results in charts, pilots, etc, for example Admiralty... More Details
  • General Nautical Terminology IALA

    The International Association of Lighthouse Authorities (IALA) is an international organisation that aims to promote safe, efficient, and...

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  • General Nautical Terminology ICC

    An official document that certifies a person's ability to operate a pleasure craft in countries that recognise it. 

    The International...

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  • Flag / Pennant, Signals & Communication Code Flag India (I)

    The International Maritime Signal Flag India.

    Meaning

    I am altering course to port.

  • Flag / Pennant, General Nautical Terminology, Signals & Communication ICS

    A system of flags, codes, and symbols used by ships to communicate essential messages and ensure safety at sea, regardless of language...

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  • Did you know?, General Nautical Terminology, Navigation IDL

    An imaginary longitudinal line located at approximately 180 degrees longitude serving as the demarcation where the calendar date changes by one...

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  • General Nautical Terminology, Navigation IHO

    An intergovernmental organisation dedicated to ensuring the uniformity and standardisation of hydrographic and nautical charting practices...

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

    This shape represents the Letter I (Flag Semaphore) and the Number 9 (Flag Semaphore).

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

    International Morse Code sequence representing the letter I.

  • Organisation IMO

    A specialised agency of the United Nations headquartered in London and responsible for regulating shipping, the IMO has 175 Member States.

    The...

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  • General Nautical Terminology Impeller

    An impeller is a rotating component within a pump or compressor that is used to impart motion to a fluid. It typically consists of blades or...

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