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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.
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      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
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        We help you navigate through the complex world of training and help find what’s best for you.
  • Know-How

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      • 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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Published:25th October 20248th October 2025 Last Updated:8th October 2025
General Nautical Terminology | Parts of a Boat

Catamaran

A type of multihulled vessel featuring two parallel hulls of equal size, connected by a deck or framework, offering stability, speed, and efficiency in the water.

A catamaran is a distinctive type of watercraft that stands out due to its twin-hull design. Unlike traditional monohull boats, which rely on a single hull for buoyancy and stability, a catamaran’s two hulls are spaced apart and connected by a deck or crossbeams. This configuration provides several advantages, including enhanced stability, as the wide stance of the hulls reduces the vessel’s tendency to roll, even in choppy seas. This makes catamarans particularly popular for leisure cruising, as passengers often find the ride smoother and more comfortable compared to monohulls. Additionally, the design is highly efficient, as the reduced wetted surface area of the hulls minimises drag, allowing catamarans to achieve higher speeds with less power. This efficiency also translates into better fuel economy for motorised catamarans and improved performance for sailing versions.

Catamarans are versatile and come in various sizes and configurations, ranging from small recreational sailboats to luxurious yachts and even large ferries. They are often used for activities such as coastal cruising, long-distance voyages, and water sports. The spacious deck area, afforded by the wide beam, makes them ideal for social gatherings and extended stays on the water. Their shallow draft also allows them to navigate closer to shorelines and access areas that might be off-limits to deeper-draft vessels. Overall, the catamaran’s innovative design and functionality have made it a favourite among sailors, holidaymakers, and marine enthusiasts alike.

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