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, 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.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.
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 & TerminologyUnderstanding 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 FlashcardsFlashcards 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 BlogFrom 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.A surveyed depth value printed at a specific position on a nautical chart. The value is reduced to the chart’s stated datum and may not represent the shallowest depth between soundings. Survey age, quality, seabed change, tide and the vessel’s required clearance must all be considered.
A defined reference surface from which elevations or depths are measured. Land surveys, charts and tide tables may use different vertical datums, and their numerical values are not interchangeable without a known separation. Mariners must identify the datum attached to every height, depth and clearance calculation.
A reference level derived from tidal observations and used for tidal heights or coastal elevations. Examples include mean high water and mean low water, while chart datum is selected for charted depths and predicted tide heights. A tidal datum is local to a place and epoch and must not be confused with a land-survey vertical…
The vertical distance between a vessel’s lowest point and the seabed or other underwater obstruction. A safe allowance must consider chart datum, predicted and observed tide, squat, heel, trim, wave response, water density and sounding uncertainty. Required margins depend on the vessel, waterway and operating procedures and should be monitored throughout a constrained passage.
An instrument displaying water depth or the measured distance beneath a vessel from an acoustic transducer or other sensor. Most small-craft depth instruments are echo sounders that time a sound pulse reflected from the seabed. The display may be offset to show depth below the transducer, below the keel or an estimated total depth. The…
The UK government organisation responsible for hydrographic data and ADMIRALTY maritime navigation products. UKHO compiles and supplies official charts, electronic navigational charts, sailing directions, tide products, notices and other information for safe navigation, drawing on surveys and data from many authorities. It is an executive agency of the Ministry of Defence and the UK’s national…
The IHO framework for creating interoperable digital maritime data-product specifications. S-100 is based on the ISO 19100 family of geographic-information standards and provides registries, feature catalogues, portrayal, metadata and exchange mechanisms. Product specifications built on it include S-101 electronic navigational charts, S-102 bathymetric surfaces and S-104 water levels. S-100 is a framework rather than a…
An intergovernmental organisation that coordinates international hydrography and standards for nautical charts and marine geospatial information. The IHO develops specifications, guidance and capacity-building programmes to improve the consistency and availability of hydrographic data and services. National hydrographic offices remain responsible for surveying and publishing official products in their jurisdictions. Its standards include the S-57 framework…
A depositional landform built where a river delivers sediment into a sea, lake or other relatively still body of water. As flow slows, sediment is deposited and the river may divide into distributary channels. Delta shape and growth depend on sediment supply, waves, tides, currents, sea level and human alteration. For navigation, deltas may contain…
A unit of length equal to six feet, or 1.8288 metres, traditionally used for water depth and cable length. Older charts and sounding records may show depths in fathoms, sometimes with additional feet. Modern charts commonly use metres, and the chart’s unit and vertical datum must always be checked before using a depth. One fathom…
If you belive the Earth is flat, you're about to fall of the end...
If you belive the Earth is flat, you're about to fall of the end...
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