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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
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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: 57
  • Term
    Definition
  • General Nautical Terminology Magnetic North

    Magnetic North refers to the direction indicated by a magnetic compass, which points towards the Earth’s magnetic north pole. This differs from...

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  • Organisation MAIB

    A UK government agency responsible for investigating marine accidents and incidents to improve maritime safety. Part of the Department for...

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  • General Nautical Terminology Mail SailTo hoist the sails and get under way
  • General Nautical Terminology Mainsail

    The principal and typically largest sail on a sailing vessel, attached to the mainmast and used to harness wind power for propulsion.

    The...

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  • General Nautical Terminology Mainsheet Traveller

    The mainsheet traveller is a system on a sailboat that allows for adjustment of the mainsheet attachment point along a track that runs across the...

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  • General Nautical Terminology Make FastTo secure the vessel with mooring lines to the jetty or to tie up to a buoy
  • General Nautical Terminology Making Way

    A vessel that is moving through the water under its own power, whether by engine, sail, or other means.

    A vessel is said to be "making way"...

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  • General Nautical Terminology, Weather (Meteorology) Malin

    Sea area of the Met Office Shipping Forecast. Located off the north coast of Ireland, near Malin Head.

    After Malin Head, Ireland’s northernmost...

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  • General Nautical Terminology, Safety Man Overboard

    A situation where a person has fallen from a vessel into the water, requiring immediate rescue actions. 

    A man overboard situation is one of...

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  • General Nautical Terminology Marina

    A specially designed harbour or dock where boats and yachts are moored, often offering services such as refuelling, repairs, and...

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  • Organisation Marine Accident and Investigation Branch (MAIB)

    A UK government agency responsible for investigating marine accidents and incidents to improve maritime safety. Part of the Department for...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • 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...

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  • Organisation MCA

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

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  • 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.

  • General Nautical Terminology Mean High Water Neaps (MHWN)

    Mean High Water Neaps (MHWN) refers to the average height of the higher of the two daily high tides that occur during neap tides. Neap tides...

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  • General Nautical Terminology, Navigation Mean High Water Springs (MHWS)

    A tidal datum representing the average height of the high water level during spring tides over a specific period, typically measured over a...

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  • General Nautical Terminology Mean Low Water Neaps (MLWN)

    Mean Low Water Neaps (MLWN) is a tidal datum representing the average lowest water level during neap tides. Neap tides occur when the...

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  • 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...

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  • 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)...

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  • 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...

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  • 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)...

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  • General Nautical Terminology MHWN

    Mean High Water Neaps (MHWN) refers to the average height of the higher of the two daily high tides that occur during neap tides. Neap tides...

    More Details
  • General Nautical Terminology, Navigation MHWS

    A tidal datum representing the average height of the high water level during spring tides over a specific period, typically measured over a...

    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...

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  • 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.

  • General Nautical Terminology MLWN

    Mean Low Water Neaps (MLWN) is a tidal datum representing the average lowest water level during neap tides. Neap tides occur when the...

    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
  • Courses, RYA Multihull Level 1 - Start SailingThe RYA Multihull Level 1 course introduces participants to the basics of sailing multihulls. Participants practice rigging, steering, and sail... More Details
  • Courses, RYA Multihull Level 2 - Basic SkillsThe RYA Multihull Level 2 course builds on the skills learned in Level 1, focusing on independent sailing in multihulls. Participants practice... More Details
  • Courses, RYA Multihull Level 3 - Better SailingThe RYA Multihull Level 3 course refines sailors’ techniques, focusing on advanced boat handling and performance optimization. Participants... More Details
  • Courses, RYA Multihull Performance SailingThe RYA Multihull Performance Sailing course is designed for experienced sailors looking to optimize their skills in high-performance multihulls.... More Details
  • Courses, RYA Multihull Regional RacingThe RYA Multihull Regional Racing course is tailored for sailors competing at a regional level in multihull events. This advanced program focuses... More Details
  • Courses, RYA Multihull Sailing With SpinnakersThe RYA Multihull Sailing With Spinnakers course focuses on spinnaker handling in multihulls. Participants learn to rig, hoist, and trim... More Details
  • Courses, RYA Multihull Seamanship SkillsThe RYA Multihull Seamanship Skills course builds essential practical skills for handling multihulls in a variety of conditions. Participants... More Details
  • Courses, RYA Multihull Start RacingThe RYA Multihull Start Racing course introduces sailors to the fundamentals of racing multihulls. Participants practice starting techniques, boat... More Details

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