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Glossary

• 2 – Two (TOO) (25th October 2024)
• 3 – Three (TREE) (25th October 2024)
• 4 – Four (FOW-er) (25th October 2024)
• 406 MHz Beacon (30th August 2026)
• 5 – Five (FIFE) (25th October 2024)
• 6 – Six (SIX) (25th October 2024)
• 7 – Seven (SEV-en) (25th October 2024)
• 8 – Eight (AIT) (25th October 2024)
• 9 – Nine (NIN-er) (25th October 2024)
• Abaft (25th October 2024)
• Abaft the Beam (30th August 2026)
• Abate (25th October 2024)
• Abeam (25th October 2024)
• Abort Point (30th August 2026)
• Above Board (25th October 2024)
• Above Deck (25th October 2024)
• Accidental Gybe (2nd January 2025)
• Adrift (25th October 2024)
• Advanced Pilotage (4th February 2025)
• Advanced Plus Windsurfing (4th February 2025)
• Advanced Windsurfing (4th February 2025)
• Aerodynamics (8th October 2026)
• Afloat (25th October 2024)
• Aft (25th October 2024)
• After Deck (25th October 2024)
• Aground (25th October 2024)
• Ahead (25th October 2024)
• Ahoy (25th October 2024)
• Air-cushion Vessel (25th October 2024)
• Alee (25th October 2024)
• All at sea (25th October 2024)
• All-round Light (30th August 2026)
• Aloft (25th October 2024)
• Alongside (25th October 2024)
• Aloof (25th October 2024)
• Alpha (26th October 2024)
• Alternating Light (Al) (2nd September 2026)
• American Sailing Association (ASA) (24th February 2025)
• Amidships (25th October 2024)
• Amplitude Modulation (AM) (20th July 2025)
• Anchor (25th October 2024)
• Anchor Aweigh (25th October 2024)
• Anchor Ball (25th October 2024)
• Anchor Buoy (25th October 2024)
• Anchor Cable (25th October 2024)
• Anchor Crown (7th January 2026)
• Anchor Light (25th October 2024)
• Anchor Locker (25th October 2024)
• Anchor Rode (25th October 2024)
• Anchor Roller (25th October 2024)
• Anchor Sea-fastening (30th August 2026)
• Anchor Set (25th October 2024)
• Anchor Setting (30th August 2026)
• Anchor Shackle (30th August 2026)
• Anchor Shank (7th January 2026)
• Anchor Stock (7th January 2026)
• Anchor Watch (30th August 2026)
• Anchor Windlass (25th October 2024)
• Anchorage (25th October 2024)
• Anchoring (30th August 2026)
• Anemometer (8th October 2026)
• Angle of Attack (8th October 2026)
• Angle of Vanishing Stability (AVS) (25th October 2024)
• Angle of Vanishing Stability (AVS) (25th October 2024)
• ANNEX I: Positioning and Technical Details of Lights and Shapes (21st December 2024)
• ANNEX II: Additional signals for fishing vessel fishing in close proximity (21st December 2024)
• ANNEX III: Technical details of sound signal appliances (21st December 2024)
• ANNEX IV: Distress Signals (21st December 2024)
• Annual Change (30th August 2026)
• Antifoul (25th October 2024)
• Antimeridian (30th August 2026)
• Apparent Wind (25th October 2024)
• Apparent Wind Angle (30th August 2026)
• Appraisal (30th August 2026)
• Appraise, Plan, Execute and Monitor (APEM) (6th May 2025)
• Approximate Charted Information (approx) (2nd September 2026)
• Arc of Visibility (30th August 2026)
• Archipelagic Sea Lane (ASL) (2nd September 2026)
• Area to Be Avoided (ATBA) (2nd September 2026)
• As the Crow Flies (25th October 2024)
• Ashore (25th October 2024)
• Astern (25th October 2024)
• Astronomical Tide (30th August 2026)
• Asymmetric Spinnaker (26th May 2025)
• At loggerheads (25th October 2024)
• Attention (Flag Semaphore) (18th December 2024)
• Automatic Identification System (25th October 2024)
• Autonomous Underwater Vehicle (AUV) (25th October 2024)
• Autopilot (25th October 2024)
• Auxiliary (25th October 2024)
• Awash (25th October 2024)
• Azimuth (8th October 2026)
• Baby Stay (25th October 2024)
• Back (Wind) (25th October 2024)
• Back a Sail (25th October 2024)
• Backed Headsail (30th August 2026)
• Backstay (25th October 2024)
• Bail (25th October 2024)
• Bailer (25th October 2024)
• Bailey (21st July 2025)
• Ball (Day Shape) (25th October 2024)
• Ballast (25th October 2024)
• Bar (25th October 2024)
• Barber Hauler (5th April 2025)
• Bare Poles (25th October 2024)
• Barometer (8th October 2026)
• Basic Sea Survival Certificate (4th February 2025)
• Bathing Platform (25th October 2024)
• Batten (25th October 2024)
• Batten Pocket (25th October 2024)
• Beach (25th October 2024)
• Beacon (25th October 2024)
• Beacon and Buoy Abbreviations on Nautical Charts (2nd September 2026)
• Beacon Tower (BnTr) (2nd September 2026)
• Beam (25th October 2024)
• Beam Reach (25th October 2024)
• Bear Away (25th October 2024)
• Bearing (25th October 2024)
• Bearing to Waypoint (25th October 2024)
• Beating (25th October 2024)
• Beaufort Scale (25th October 2024)
• Below Decks (25th October 2024)
• Bend Radius (30th August 2026)
• Bermudan Rig (25th October 2024)
• Berth (25th October 2024)
• Berth-to-berth Planning (30th August 2026)
• Bi-colour Light (25th October 2024)
• Bight (25th October 2024)
• Bilge Pump (25th October 2024)
• Bilges (25th October 2024)
• Bimini Top (7th March 2025)
• Binnacle (25th October 2024)
• Biscay (21st July 2025)
• Bitter End (25th October 2024)
• Blind Sector (30th August 2026)
• Block (25th October 2024)
• Block and Tackle (30th August 2026)
• Boat Balance (30th August 2026)
• Boat Hook (25th October 2024)
• Boat Wind (Motion Wind) (25th October 2024)
• Boatswain's Call (30th August 2026)
• Bollard (25th October 2024)
• Boom (25th October 2024)
• Boom Out (25th October 2024)
• Boom Preventer (25th October 2024)
• Boom Sweep (30th August 2026)
• Boom Vang (Kicking Strap) (25th October 2024)
• Bora (15th July 2025)
• Bosun (Boatswain) (25th October 2024)
• Boundary Conditions (30th August 2026)
• Bow (25th October 2024)
• Bow Line (25th October 2024)
• Bow Pulpit (25th October 2024)
• Bow Spring (25th October 2024)
• Bowline (25th October 2024)
• Bowsprit (25th October 2024)
• Bravo (25th October 2024)
• Break Out an Anchor (30th August 2026)
• Breakwater (25th October 2024)
• Breast Line (30th August 2026)
• Broach (25th October 2024)
• Broad Reach (25th October 2024)
• Bruce Anchor (28th February 2025)
• Bulkhead (25th October 2024)
• Bung (25th October 2024)
• Bunk (25th October 2024)
• Buoy (25th October 2024)
• Buoyancy Aid (25th October 2024)
• Buoyant Orange Smoke Signal (19th March 2025)
• Burgee (25th October 2024)
• Bury Length (30th August 2026)
• By and Large (26th March 2025)
• Cabin (25th October 2024)
• Cable (25th October 2024)
• Cable (Distance) (25th October 2024)
• Call Sign (25th October 2024)
• Cam Cleat (7th March 2025)
• Cancel—Disregard (Flag Semaphore) (26th October 2024)
• Cap Shroud (30th August 2026)
• Capsize (25th October 2024)
• Capsize Recovery (30th August 2026)
• Capstan (8th October 2026)
• Cardinal Bearing (25th October 2024)
• Cardinal Mark (25th October 2024)
• Cargo Securing (30th August 2026)
• Carrier Wave (30th August 2026)
• Cartography (8th October 2026)
• Cast Off (25th October 2024)
• Catamaran (25th October 2024)
• Catenary (30th August 2026)
• Cavitation (30th August 2026)
• Celestial Navigation (8th October 2026)
• Centre of Effort (8th October 2026)
• Centre of Lateral Resistance (8th October 2026)
• CEVNI (30th August 2026)
• CEVNI test online (4th February 2025)
• Chafing (25th October 2024)
• Chain Locker (30th August 2026)
• Chain Stopper (30th August 2026)
• Chainplate (7th March 2025)
• Challenger of Record (25th October 2024)
• Chandler (25th October 2024)
• Channel (25th October 2024)
• Charlie (25th October 2024)
• Chart Datum (25th October 2024)
• Chart Meridian (30th August 2026)
• Chart Plotter (25th October 2024)
• Chart Table (25th October 2024)
• Charted Depth (25th October 2024)
• Charted Light Colours (2nd September 2026)
• Charted Sounding (30th August 2026)
• Chartwork (30th August 2026)
• Checkstay (30th August 2026)
• Chief Mate (14th November 2024)
• Chine (25th October 2024)
• Chock-a-block (25th October 2024)
• Chop (25th October 2024)
• Chronometer (25th October 2024)
• Circular Marine Radiobeacon (RC) (2nd September 2026)
• Clay Seabed (Cy) (2nd September 2026)
• Clean Bill of Health (26th March 2025)
• Clear (25th October 2024)
• Clear (25th October 2024)
• Clear (25th October 2024)
• Clearance (25th October 2024)
• Cleat (25th October 2024)
• Cleat Hitch (8th October 2026)
• Clew (25th October 2024)
• Clock Bearing (30th August 2026)
• Close Reach (13th July 2026)
• Close-hauled (25th October 2024)
• Closest Point of Approach (25th October 2024)
• Clove Hitch (25th October 2024)
• Coachroof (25th October 2024)
• Coaming (25th October 2024)
• Coastal Skipper Practical (Motor) (4th February 2025)
• Coastal Skipper Practical (Sail) (4th February 2025)
• Coastal Skipper/Yachtmaster Offshore Theory (4th February 2025)
• Cobbles Seabed (Cb) (2nd September 2026)
• Cocked Hat (25th October 2024)
• Cockpit (25th October 2024)
• Cockpit Coaming (30th August 2026)
• Cockpit Locker (30th August 2026)
• Code Flag Alpha (A) (25th October 2024)
• Code Flag Bravo (B) (2nd January 2025)
• Code Flag Charlie (C) (2nd January 2025)
• Code Flag Delta (D) (2nd January 2025)
• Code Flag Echo (E) (2nd January 2025)
• Code Flag Foxtrot (F) (2nd January 2025)
• Code Flag Golf (G) (2nd January 2025)
• Code Flag Hotel (H) (2nd January 2025)
• Code Flag India (I) (2nd January 2025)
• Code Flag Juliett (J) (2nd January 2025)
• Code Flag Kilo (K) (2nd January 2025)
• Code Flag Lima (L) (2nd January 2025)
• Code Flag Mike (M) (2nd January 2025)
• Code Flag November (N) (2nd January 2025)
• Code Flag Oscar (O) (2nd January 2025)
• Code Flag Papa (P) (2nd January 2025)
• Code Flag Quebec (Q) (2nd January 2025)
• Code Flag Romeo (R) (2nd January 2025)
• Code Flag Sierra (S) (2nd January 2025)
• Code Flag Tango (T) (2nd January 2025)
• Code Flag Uniform (U) (2nd January 2025)
• Code Flag Victor (V) (2nd January 2025)
• Code Flag Whiskey (W) (2nd January 2025)
• Code Flag Xray (X) (2nd January 2025)
• Code Flag Yankee (Y) (3rd January 2025)
• Code Flag Zulu (Z) (3rd January 2025)
• Code Zero (7th March 2025)
• Collision Course (25th October 2024)
• Commissioners of Irish Lights (4th November 2024)
• Companionway (25th October 2024)
• Companionway Steps (25th October 2024)
• Compass (25th October 2024)
• Compass Add East for True (4th November 2024)
• Compass Bearing (30th August 2026)
• Compass Card (30th August 2026)
• Compass Deviation (25th October 2024)
• Compass Deviation Card (25th October 2024)
• Compass Error (30th August 2026)
• Compass Heading (30th August 2026)
• Compass Rose (25th October 2024)
• Compass Swing (30th August 2026)
• Competent Crew (4th February 2025)
• Compilation Scale (30th August 2026)
• Consol Beacon (RW) (2nd September 2026)
• Constant Bearing, Decreasing Range (CBDR) (25th October 2024)
• Constrained by Draught (25th October 2024)
• Coordinate Format (30th August 2026)
• Coordinated Universal Time (UTC) (3rd February 2025)
• Coral Seabed (Co) (2nd September 2026)
• Coriolis Effect (22nd August 2025)
• Cospas-Sarsat (19th March 2025)
• Counter Stern (30th August 2026)
• Course Made Good (30th August 2026)
• Course Over Ground (25th October 2024)
• Course to Steer (25th October 2024)
• Courtesy Ensign (25th October 2024)
• Covers (cov) (2nd September 2026)
• CQR Anchor (25th October 2024)
• Crew (25th October 2024)
• Cringle (25th October 2024)
• Cromarty (21st July 2025)
• Cross Track Error (25th October 2024)
• Cruising Level 1 - Start Sailing (4th February 2025)
• Cruising Level 2 - Basic Skills (4th February 2025)
• Cumulonimbus (8th October 2026)
• Current (25th October 2024)
• Cutlass (25th October 2024)
• Cutless Bearing (25th October 2024)
• Cyclic Loading (30th August 2026)
• Cyclone (25th October 2024)
• Cyclonic (25th October 2024)
• Cylinder (Day Shape) (30th August 2026)
• Daggerboard (8th October 2026)
• Dan Buoy (25th October 2024)
• Danforth Anchor (28th February 2025)
• Dangerous Wreck (2nd September 2026)
• Davit (25th October 2024)
• Day Shape (25th October 2024)
• Day Skipper Practical (Motor) (4th February 2025)
• Day Skipper Practical (Sail) (4th February 2025)
• Day Skipper Theory (4th February 2025)
• Dead Reckoning (25th October 2024)
• Deck Department (30th August 2026)
• Deck Fill (8th October 2026)
• Deck Officer (14th November 2024)
• Deck-stepped Mast (30th August 2026)
• Deep-water Route (DW) (2nd September 2026)
• Delta (25th October 2024)
• Delta (1st January 2025)
• Delta Anchor (1st January 2025)
• Departure Plan (30th August 2026)
• Depression (25th October 2024)
• Depth Contour (25th October 2024)
• Depth Gauge (23rd April 2026)
• Dew Point (8th October 2026)
• Diaphone (25th October 2024)
• Diesel Engine (4th February 2025)
• Differential GPS (DGPS) (2nd September 2026)
• Digital Selective Calling (8th February 2025)
• Dilution of Precision (DOP) (25th October 2024)
• Dinghy (25th October 2024)
• Dinghy Club Racing (4th February 2025)
• Dinghy Day Sailing (4th February 2025)
• Dinghy Foiling First Flights (4th February 2025)
• Dinghy Foiling Performance Flights (4th February 2025)
• Dinghy Foiling Sustained Flights (4th February 2025)
• Dinghy Level 1 - Start Sailing (4th February 2025)
• Dinghy Level 2 - Basic Skills (4th February 2025)
• Dinghy Level 3 - Better Sailing (4th February 2025)
• Dinghy Performance Sailing (4th February 2025)
• Dinghy Regional Racing (4th February 2025)
• Dinghy Sailing with Spinnakers (4th February 2025)
• Dinghy Seamanship Skills (4th February 2025)
• Dinghy Start Racing (4th February 2025)
• Dip the Ensign (25th October 2024)
• Direction of Buoyage (25th October 2024)
• Directional Light (25th October 2024)
• Directional Radiobeacon (RD) (2nd September 2026)
• Discoloured Water (Discol) (2nd September 2026)
• Displacement (25th October 2024)
• Displacement Vessel (25th October 2024)
• Distance (25th October 2024)
• Distance Made Good (30th August 2026)
• Distance to Waypoint (25th October 2024)
• Distress Flares (25th October 2024)
• Distress Message (30th August 2026)
• Distress Signal (30th August 2026)
• Dividers (25th October 2024)
• Dodger (25th October 2024)
• Dog Watch (27th March 2025)
• Dogger (21st July 2025)
• Dolphin (25th October 2024)
• Double Sheet Bend (8th October 2026)
• Double Up (25th October 2024)
• Douse (25th October 2024)
• Dover (21st July 2025)
• Downflooding (30th August 2026)
• Downflooding Angle (30th August 2026)
• Downhaul (25th October 2024)
• Downstream (25th October 2024)
• Downwind (25th October 2024)
• Drag (25th October 2024)
• Draught (25th October 2024)
• Dredger (25th October 2024)
• Dressing a Knot (30th August 2026)
• Dries (dr) (2nd September 2026)
• Drift (25th October 2024)
• Drifter (8th October 2026)
• Drifting Buoy (30th August 2026)
• Drogue (25th October 2024)
• Drying Height (25th October 2024)
• DSC Distress Alert (30th August 2026)
• Dynamic Lift (30th August 2026)
• Dyneema (25th October 2024)
• Ease Out (25th October 2024)
• Ebb Tide (25th October 2024)
• Echo (25th October 2024)
• Echo Sounder (25th October 2024)
• Echo Sounding (25th October 2024)
• Eco Mooring Buoy (2nd June 2025)
• Electronic Chart Display and Information System (ECDIS) (25th October 2024)
• Electronic Navigational Chart (25th October 2024)
• Emergency Position-Indicating Radio Beacon (25th October 2024)
• Emergency Steering (30th August 2026)
• Emergency Tiller (30th August 2026)
• Enhanced Group Calling (30th August 2026)
• Ensign (25th October 2024)
• Environmentally Sensitive Sea Area (ESSA) (2nd September 2026)
• EPIRB (30th August 2026)
• Error (Flag Semaphore) (26th October 2024)
• Error Signal (Flag Semaphore) (26th October 2024)
• Essential Navigation and Seamanship (4th February 2025)
• Estimated Position (25th October 2024)
• Estimated Time of Arrival (25th October 2024)
• Etesian Winds (Meltemi) (15th July 2025)
• European Centre for Medium-Range Weather Forecasts (ECMWF) (10th November 2025)
• Even Keel (25th October 2024)
• Exclusive Economic Zone (EEZ) (2nd September 2026)
• Existence Doubtful (ED) (2nd September 2026)
• Eye Splice (25th October 2024)
• Faeroes (21st July 2025)
• Fair (25th October 2024)
• Fair Isle (21st July 2025)
• Fairlead (25th October 2024)
• Fairway (25th October 2024)
• Fairway Mark (25th October 2024)
• Fall Off (30th August 2026)
• Fastnet (21st July 2025)
• Fathom (25th October 2024)
• Feeling Blue (25th October 2024)
• Fender (25th October 2024)
• Fender Board (30th August 2026)
• Ferry Gliding (2nd June 2025)
• Fetch (25th October 2024)
• Fid (25th October 2024)
• Figure of Eight (8th January 2025)
• Fine Seabed Material (f) (2nd September 2026)
• Fire Blanket (8th October 2026)
• Fire Extinguisher (8th October 2026)
• First Aid (4th February 2025)
• First Substitute (ICS Flag) (28th December 2024)
• First-aid Kit (8th October 2026)
• Fisher (21st July 2025)
• Fisherman’s Knot (8th October 2026)
• FitzRoy (21st July 2025)
• Five Essentials (30th August 2026)
• Fix (25th October 2024)
• Fixed and Flashing Light (FFl) (2nd September 2026)
• Fixed Light (F) (2nd September 2026)
• Flag Semaphore (26th October 2024)
• Flag State (30th August 2026)
• Flake (25th October 2024)
• Flaking a Line (25th October 2024)
• Flaking a Sail (25th October 2024)
• Flame-failure Device (30th August 2026)
• Flashing Light (25th October 2024)
• Flood Tide (25th October 2024)
• Fluke (Anchor) (25th October 2024)
• Fly Out (25th October 2024)
• Fo'c'sle (Forecastle) (25th October 2024)
• Fog (25th October 2024)
• Foghorn (25th October 2024)
• Foil Take-off (30th August 2026)
• Folding Propeller (25th October 2024)
• Following Sea (25th October 2024)
• Foot (Sail) (25th October 2024)
• Fore-and-aft (25th October 2024)
• Foredeck (25th October 2024)
• Foreguy (30th August 2026)
• Forehatch (25th October 2024)
• Forepeak (25th October 2024)
• Foresail (25th October 2024)
• Forestay (25th October 2024)
• Foretriangle (25th October 2024)
• Forth (21st July 2025)
• Forties (21st July 2025)
• Forward (25th October 2024)
• Foul (25th October 2024)
• Foul Anchor (25th October 2024)
• Foul-weather Gear (8th October 2026)
• Foxtrot (25th October 2024)
• Fractional Rig (30th August 2026)
• Free-surface Effect (30th August 2026)
• Freeboard (25th October 2024)
• Frequency Modulation (FM) (20th July 2025)
• Fuel Collar (25th October 2024)
• Full Rudder (25th October 2024)
• Full-length Batten (30th August 2026)
• Fully Developed Sea (30th August 2026)
• Furl (25th October 2024)
• Furling (25th October 2024)
• Furling Drum (7th March 2025)
• Gaff (25th October 2024)
• Gaff Rig (25th October 2024)
• Gale (25th October 2024)
• Gale Warning (30th August 2026)
• Galley (25th October 2024)
• Galvanic Corrosion (30th August 2026)
• Gelcoat (25th October 2024)
• General Lighthouse Authorities (4th November 2024)
• Genoa (25th October 2024)
• Genoa Track (8th October 2026)
• Geodetic Datum (30th August 2026)
• Geometric Dilution of Precision (GDOP) (25th October 2024)
• German Bight (21st July 2025)
• German Maritime Waterways (30th August 2026)
• Gimbal (8th October 2025)
• Give Way (25th October 2024)
• Give-way Vessel (25th October 2024)
• Glass-reinforced Plastic (GRP) (25th October 2024)
• Global Forecast System (GFS) (10th November 2025)
• Global Maritime Distress and Safety System (GMDSS) (25th October 2024)
• Global Navigation Satellite System (25th October 2024)
• Global Positioning System (GPS) (25th October 2024)
• GMDSS (30th August 2026)
• GMDSS Sea Areas (20th July 2025)
• Gnomonic Projection (25th October 2024)
• Go About (25th October 2024)
• Going Astern (25th October 2024)
• Golf (25th October 2024)
• Gooseneck (25th October 2024)
• Goosewinged (25th October 2024)
• Grab Bag (19th May 2026)
• Grab Rail (25th October 2024)
• Gravel Seabed (G) (2nd September 2026)
• Great-circle Distance (30th August 2026)
• Great-circle Route (30th August 2026)
• Green Light or Mark (G) (2nd September 2026)
• Greenwich Mean Time (GMT) (3rd February 2025)
• GRIB (Gridded Binary) (10th November 2025)
• Ground Tackle (25th October 2024)
• Ground Track (30th August 2026)
• Group Light Characteristic (2nd September 2026)
• Guard Rail (25th October 2024)
• Guardrail (25th October 2024)
• Gunwale (25th October 2024)
• Guy (Rigging) (25th October 2024)
• Gybe (25th October 2024)
• Gybe-oh! (25th October 2024)
• Hail (30th August 2026)
• Half Hitch (8th October 2026)
• Halyard (25th October 2024)
• Halyard Winch (8th October 2026)
• Halyard Wrap (30th August 2026)
• Hand-bearing Compass (25th October 2024)
• Hand-held Red Flare (19th March 2025)
• Handrail (25th October 2024)
• Handy Billy (25th October 2024)
• Hank (Sail) (25th October 2024)
• Hanked-on Sail (20th April 2026)
• Harbour (25th October 2024)
• Harden In (25th October 2024)
• Harden Up (25th October 2024)
• Hatch (25th October 2024)
• Hatch Coaming (30th August 2026)
• Hatch Dog (30th August 2026)
• Haul In (25th October 2024)
• Head (25th October 2024)
• Head (25th October 2024)
• Head to Wind (25th October 2024)
• Heading (25th October 2024)
• Headland (25th October 2024)
• Headsail (25th October 2024)
• Headsail Lead (30th August 2026)
• Headway (25th October 2024)
• Heave To (Heaving-to) (25th October 2024)
• Hebrides (21st July 2025)
• Heel (Vessel Motion) (25th October 2024)
• Height of Light (25th October 2024)
• Height of Tide (25th October 2024)
• Helm (25th October 2024)
• Helm Order (30th August 2026)
• Helmsman's Practical (4th February 2025)
• Helmsperson (25th October 2024)
• High Frequency (HF) (8th February 2025)
• High Water (30th August 2026)
• Highest Astronomical Tide (HAT) (25th October 2024)
• Hitch (25th October 2024)
• HM Coastguard (25th October 2024)
• HM Nautical Almanac Office (HMNAO) (11th February 2025)
• Hoist (25th October 2024)
• Holding Ground (30th August 2026)
• Holding Tank (25th October 2024)
• Horizontal Dilution of Precision (HDOP) (25th October 2024)
• Horseshoe Lifebuoy (25th October 2024)
• Hotel (25th October 2024)
• Hounds (25th October 2024)
• House Flag (25th October 2024)
• Hull (25th October 2024)
• Hull Speed (25th October 2024)
• Humber (21st July 2025)
• Hurricane (Tropical Cyclone) (25th October 2024)
• Hurricane Force (25th October 2024)
• Hydrodynamics (8th October 2026)
• Hydrofoil (25th October 2024)
• Hydrographic Survey (30th August 2026)
• Hydrography (25th October 2024)
• Hydrostatic Release Unit (30th August 2026)
• IALA Region A (30th August 2026)
• IALA Region B (30th August 2026)
• ICOsahedral Nonhydrostatic Model (ICON) (10th November 2025)
• IMO Standard Marine Communication Phrases (SMCP) (20th July 2025)
• Impeller (25th October 2024)
• Impressment (30th August 2026)
• Improve your Wingsurfing (4th February 2025)
• In Irons (25th October 2024)
• In Stays (25th October 2024)
• In-mast Furling (30th August 2026)
• India (25th October 2024)
• Inhauler (5th April 2025)
• Inland Waterways Crew (4th February 2025)
• Inland Waterways Helmsman's (4th February 2025)
• Inner Forestay (30th August 2026)
• Inshore (25th October 2024)
• Inshore Traffic Zone (30th August 2026)
• Inshore Waters Forecast (30th August 2026)
• Intensified Light Sector (Intens) (2nd September 2026)
• Intermediate Windsurfing (4th February 2025)
• Intermediate Windsurfing (Planing) (4th February 2025)
• International Certificate for Operators of Pleasure Craft (ICC) (24th February 2025)
• International Code of Signals (ICS) (25th October 2024)
• International Convention for the Prevention of Pollution from Ships (MARPOL) (25th October 2024)
• International Convention for the Safety of Life at Sea (SOLAS) (25th October 2024)
• International Convention on Standards of Training, Certification, and Watchkeeping for Seafarers (14th November 2024)
• International Date Line (3rd February 2025)
• International Hydrographic Organization (10th January 2025)
• International Maritime Conventions (14th November 2024)
• International Maritime Organization (IMO) (25th October 2024)
• International Maritime Signal Flags (28th December 2024)
• International Meridian Conference (3rd February 2025)
• International Mobile Satellite Organization (IMSO) (19th March 2025)
• International Morse Code (24th December 2024)
• International Organization for Marine Aids to Navigation (IALA) (25th October 2024)
• International Radiotelegraph Conference (15th November 2024)
• International Reference Meridian (30th August 2026)
• International Regulations for Preventing Collisions at Sea (25th October 2024)
• International Regulations for Preventing Collisions at Sea (COLREG) (29th May 2025)
• International Telecommunication Union (15th November 2024)
• Interrupted Quick-flashing Light (IQ) (2nd September 2026)
• Interrupted Ultra Quick-flashing Light (IUQ) (2nd September 2026)
• Interrupted Very Quick-flashing Light (IVQ) (2nd September 2026)
• Irish Sea (21st July 2025)
• Isobar (25th October 2024)
• Isolated Danger Mark (25th October 2024)
• Isophase Light (25th October 2024)
• J Measurement (30th August 2026)
• Jackstay (25th October 2024)
• Jet Stream (8th October 2026)
• Jib (25th October 2024)
• Jib Sheets (25th October 2024)
• Jon Buoy (19th March 2025)
• Juliett (25th October 2024)
• Jury Rig (25th October 2024)
• Katabatic Wind (15th July 2025)
• Kedge (25th October 2024)
• Kedge Anchor (25th October 2024)
• Kedging (30th August 2026)
• Keel (25th October 2024)
• Keel-stepped Mast (30th August 2026)
• Keelboat Club Racing (4th February 2025)
• Keelboat Day Sailing (4th February 2025)
• Keelboat Level 1 - Start Sailing (4th February 2025)
• Keelboat Level 2 - Basic Skills (4th February 2025)
• Keelboat Level 3 - Better Sailing (4th February 2025)
• Keelboat Performance Sailing (4th February 2025)
• Keelboat Regional Racing (4th February 2025)
• Keelboat Sailing with Spinnakers (4th February 2025)
• Keelboat Seamanship Skills (4th February 2025)
• Keelboat Start Racing (4th February 2025)
• Ketch (25th October 2024)
• Kicking Strap (25th October 2024)
• Kilo (25th October 2024)
• Knockdown (30th August 2026)
• Knot (14th November 2024)
• Knot (Speed) (25th October 2024)
• Laminar Flow (8th October 2026)
• Laminate (30th August 2026)
• Land Breeze (1st June 2025)
• Landfall (25th October 2024)
• Lanyard (25th October 2024)
• Large Automatic Navigational Buoy (LANBY) (2nd September 2026)
• Lash Down (25th October 2024)
• Lateral Mark (25th October 2024)
• Latitude (25th October 2024)
• Latitude Scale (30th August 2026)
• Lazarette (25th October 2024)
• Lazarette Hatch (8th October 2026)
• Lazyjacks (25th October 2024)
• Lead Line (25th October 2024)
• Leading Lights (25th October 2024)
• Leading Line (30th August 2026)
• League (25th October 2024)
• Learn to Wingsurf (4th February 2025)
• Lee (25th October 2024)
• Lee Shore (25th October 2024)
• Lee-bow Tack (8th October 2026)
• Lee-oh (25th October 2024)
• Leech (Sail) (25th October 2024)
• Leech Tension (30th August 2026)
• Leeward (25th October 2024)
• Leeway (25th October 2024)
• Leeway Angle (30th August 2026)
• Leg (25th October 2024)
• Length on the Waterline (LWL) (25th October 2024)
• Length Overall (LOA) (25th October 2024)
• Letter A (Flag Semaphore) (26th October 2024)
• Letter A (Morse Code) (24th December 2024)
• Letter B (Flag Semaphore) (26th October 2024)
• Letter B (Morse Code) (25th December 2024)
• Letter C (Flag Semaphore) (1st November 2024)
• Letter C (Morse Code) (25th December 2024)
• Letter D (Flag Semaphore) (26th October 2024)
• Letter D (Morse Code) (25th December 2024)
• Letter E (Flag Semaphore) (26th October 2024)
• Letter E (Morse Code) (25th December 2024)
• Letter F (Flag Semaphore) (26th October 2024)
• Letter F (Morse Code) (25th December 2024)
• Letter G (Flag Semaphore) (26th October 2024)
• Letter G (Morse Code) (25th December 2024)
• Letter H (Flag Semaphore) (26th October 2024)
• Letter H (Morse Code) (25th December 2024)
• Letter I (Flag Semaphore) (26th October 2024)
• Letter I (Morse Code) (25th December 2024)
• Letter J (Flag Semaphore) (26th October 2024)
• Letter J (Morse Code) (25th December 2024)
• Letter K (Flag Semaphore) (26th October 2024)
• Letter K (Morse Code) (25th December 2024)
• Letter L (Flag Semaphore) (26th October 2024)
• Letter L (Morse Code) (25th December 2024)
• Letter M (Flag Semaphore) (26th October 2024)
• Letter M (Morse Code) (25th December 2024)
• Letter N (Flag Semaphore) (26th October 2024)
• Letter N (Morse Code) (25th December 2024)
• Letter O (Flag Semaphore) (26th October 2024)
• Letter O (Morse Code) (25th December 2024)
• Letter P (Flag Semaphore) (26th October 2024)
• Letter P (Morse Code) (25th December 2024)
• Letter Q (Flag Semaphore) (26th October 2024)
• Letter Q (Morse Code) (25th December 2024)
• Letter R (Flag Semaphore) (26th October 2024)
• Letter R (Morse Code) (25th December 2024)
• Letter S (Flag Semaphore) (26th October 2024)
• Letter S (Morse Code) (25th December 2024)
• Letter T (Flag Semaphore) (26th October 2024)
• Letter T (Morse Code) (25th December 2024)
• Letter U (Flag Semaphore) (26th October 2024)
• Letter U (Morse Code) (25th December 2024)
• Letter V (Flag Semaphore) (26th October 2024)
• Letter V (Morse Code) (25th December 2024)
• Letter W (Flag Semaphore) (26th October 2024)
• Letter W (Morse Code) (25th December 2024)
• Letter X (Flag Semaphore) (26th October 2024)
• Letter X (Morse Code) (25th December 2024)
• Letter Y (Flag Semaphore) (26th October 2024)
• Letter Y (Morse Code) (25th December 2024)
• Letter Z (Flag Semaphore) (26th October 2024)
• Letter Z (Morse Code) (25th December 2024)
• Letters Follow (Flag Semaphore) (27th October 2024)
• Level 1 Start Powerboating (PB1) (4th February 2025)
• Level 2 Powerboat Handling (PB2) (4th February 2025)
• Life-raft (25th October 2024)
• Lifejacket (19th March 2025)
• Lifeline (25th October 2024)
• Light (Lt) (2nd September 2026)
• Light-vessel (2nd September 2026)
• Lighthouse (25th October 2024)
• Lima (25th October 2024)
• Line (Ropework) (25th October 2024)
• Line of Position (LOP) (20th March 2025)
• Line of Pull (30th August 2026)
• Line-of-sight Propagation (30th August 2026)
• List (25th October 2024)
• List (Vessel Stability) (19th February 2025)
• Local Lighthouse Authority (30th August 2026)
• Local Notice to Mariners (LNM) (25th October 2024)
• Lock (Waterway) (25th October 2024)
• Locker (Storage) (25th October 2024)
• Log Line (14th November 2024)
• Log Reading (25th October 2024)
• Logbook (25th October 2024)
• Long-flashing Light (LFl) (2nd September 2026)
• Longitude (25th October 2024)
• Lookout (25th October 2024)
• Loose-footed Sail (30th August 2026)
• LORAN (8th October 2026)
• Lose Way (25th October 2024)
• Low Water (30th August 2026)
• Lowest Astronomical Tide (LAT) (25th October 2024)
• Lubber Line (25th October 2024)
• Luff (Sail Edge) (25th October 2024)
• Luff Up (25th October 2024)
• Luffing (30th August 2026)
• Lull (25th October 2024)
• Lundy (21st July 2025)
• Magnetic North (25th October 2024)
• Magnetic Variation (25th October 2024)
• Mainsail (25th October 2024)
• Mainsheet Traveller (Traveler) (25th October 2024)
• Make Fast (25th October 2024)
• Make Sail (25th October 2024)
• Making Way (25th October 2024)
• Malin (21st July 2025)
• Man Overboard (Person Overboard) (26th March 2025)
• Man Overboard Recovery (30th August 2026)
• Marina (25th October 2024)
• Marine Accident Investigation Branch (4th November 2024)
• Marine Pyrotechnic (25th October 2024)
• Marine Radio VHF (SRC) (4th February 2025)
• Marine VHF Radio (19th March 2025)
• Maritime and Coastguard Agency (MCA) (25th October 2024)
• Maritime Declaration of Health (30th August 2026)
• Maritime Mobile Service Identity (MMSI) (25th October 2024)
• Maritime Rescue Coordination Centre (MRCC) (15th January 2025)
• Maritime Safety Information (25th October 2024)
• Mast (25th October 2024)
• Mast Step (25th October 2024)
• Master (30th August 2026)
• Masthead Light (25th October 2024)
• Mayday (25th October 2024)
• Mean High Water (30th August 2026)
• Mean High Water Neaps (MHWN) (25th October 2024)
• Mean High Water Springs (MHWS) (25th October 2024)
• Mean Low Water (30th August 2026)
• Mean Low Water Neaps (MLWN) (25th October 2024)
• Mean Low Water Springs (MLWS) (25th October 2024)
• Mean Sea Level (2nd September 2026)
• Mechanical Advantage (30th August 2026)
• Medium Frequency (MF) (15th January 2025)
• Mercator Projection (30th August 2026)
• Met Office (21st July 2025)
• Met Office Global Model (10th November 2025)
• Mike (25th October 2024)
• Mist (25th October 2024)
• Mistral (15th July 2025)
• Mizzen Mast (25th October 2024)
• Mole (25th October 2024)
• Monohull (25th October 2024)
• Monsoon (8th October 2026)
• Mooring (25th October 2024)
• Mooring Buoy (25th October 2024)
• Mooring Cleat (8th October 2026)
• Mooring Dolphin (30th August 2026)
• Mooring Excursion (30th August 2026)
• Mooring Ring (25th October 2024)
• Mooring Riser (30th August 2026)
• Morse Timing (30th August 2026)
• Morse-code Light (2nd September 2026)
• Motor Sailing (25th October 2024)
• Mud Seabed (M) (2nd September 2026)
• Multihull (30th August 2026)
• Multihull Club Racing (4th February 2025)
• Multihull Day Sailing (4th February 2025)
• Multihull Level 1 - Start Sailing (4th February 2025)
• Multihull Level 2 - Basic Skills (4th February 2025)
• Multihull Level 3 - Better Sailing (4th February 2025)
• Multihull Performance Sailing (4th February 2025)
• Multihull Regional Racing (4th February 2025)
• Multihull Sailing With Spinnakers (4th February 2025)
• Multihull Seamanship Skills (4th February 2025)
• Multihull Start Racing (4th February 2025)
• National Meteorological Service (30th August 2026)
• National Oceanic and Atmospheric Administration (25th October 2024)
• NATO Phonetic Alphabet (25th October 2024)
• Nautical Almanac (25th October 2024)
• Nautical Chart (25th October 2024)
• Nautical Chart Light Characteristic (2nd September 2026)
• Nautical Mile (25th October 2024)
• Nautical Mile in a Light Description (M) (2nd September 2026)
• Navigation Lights (25th October 2024)
• Navigational Warning (30th August 2026)
• NAVTEX (25th October 2024)
• Neap Range (25th October 2024)
• Neap Tide (25th October 2024)
• Near Gale (25th October 2024)
• No-go Zone (30th August 2026)
• Nominal Range of a Light (M) (2nd September 2026)
• Non-Directional Beacon (NDB) (15th January 2025)
• North Atlantic Treaty Organization (NATO) (25th October 2024)
• North Utsire (21st July 2025)
• Northern Lighthouse Board (4th November 2024)
• Not Making Way (30th August 2026)
• Not Under Command (NUC) (25th October 2024)
• Notice to Mariners (NtM) (25th October 2024)
• November (Phonetic Alphabet) (25th October 2024)
• Number 0 (Flag Semaphore) (1st November 2024)
• Number 0 (Morse Code) (25th December 2024)
• Number 1 (Flag Semaphore) (1st November 2024)
• Number 1 (Morse Code) (25th December 2024)
• Number 2 (Flag Semaphore) (27th October 2024)
• Number 2 (Morse Code) (25th December 2024)
• Number 3 (Flag Semaphore) (26th October 2024)
• Number 3 (Morse Code) (25th December 2024)
• Number 4 (Flag Semaphore) (1st November 2024)
• Number 4 (Morse Code) (25th December 2024)
• Number 5 (Flag Semaphore) (1st November 2024)
• Number 5 (Morse Code) (25th December 2024)
• Number 6 (Flag Semaphore) (1st November 2024)
• Number 6 (Morse Code) (25th December 2024)
• Number 7 (Flag Semaphore) (1st November 2024)
• Number 7 (Morse Code) (25th December 2024)
• Number 8 (Flag Semaphore) (1st November 2024)
• Number 8 (Morse Code) (25th December 2024)
• Number 9 (Flag Semaphore) (1st November 2024)
• Number 9 (Morse Code) (25th December 2024)
• Numbers Follow (Flag Semaphore) (26th October 2024)
• Numeral 0 (Flag Pennant) (25th October 2024)
• Numeral 1 (Flag Pennant) (25th October 2024)
• Numeral 2 (Flag Pennant) (27th December 2024)
• Numeral 3 (Flag Pennant) (27th December 2024)
• Numeral 4 (Flag Pennant) (28th December 2024)
• Numeral 5 (Flag Pennant) (28th December 2024)
• Numeral 6 (Flag Pennant) (28th December 2024)
• Numeral 7 (Flag Pennant) (28th December 2024)
• Numeral 8 (Flag Pennant) (28th December 2024)
• Numeral 9 (Flag Pennant) (28th December 2024)
• Numeral Pennant (2nd January 2025)
• Numerical Weather Prediction (30th August 2026)
• Obscured Light Sector (Obscd) (2nd September 2026)
• Obstruction (Obstn) (2nd September 2026)
• Occluded Front (8th October 2026)
• Occulting Light (25th October 2024)
• Ocean Data Acquisition System (ODAS) (25th October 2024)
• Officer of the Watch (OOW) (27th March 2025)
• Offshore (25th October 2024)
• Offshore Personal Survival (RYA/World Sailing) (4th February 2025)
• Offshore Wind (30th August 2026)
• Oilskins (25th October 2024)
• On the Port Bow (25th October 2024)
• On the Port Quarter (25th October 2024)
• On the Starboard Bow (25th October 2024)
• On the Starboard Quarter (25th October 2024)
• On-scene Coordinator (30th August 2026)
• Onshore (25th October 2024)
• Oscar (Phonetic Alphabet) (25th October 2024)
• Outhaul (25th October 2024)
• Overfalls (25th October 2024)
• Overhand Loop (25th October 2024)
• Overlapping Headsail (30th August 2026)
• Padeye (8th October 2026)
• Painter (25th October 2024)
• PAN PAN (25th October 2024)
• Papa (Phonetic Alphabet) (25th October 2024)
• Parallel Rules (25th October 2024)
• Particularly Sensitive Sea Area (PSSA) (2nd September 2026)
• Passage (Voyage) (25th October 2024)
• Passage Plan (20th March 2025)
• Pay Off (Sailing) (25th October 2024)
• Pay Out (25th October 2024)
• Peak Halyard (30th August 2026)
• Pebbles Seabed (P) (2nd September 2026)
• Performance Level (30th August 2026)
• Period of a Light (s) (2nd September 2026)
• Perling (4th June 2025)
• Personal Flotation Device (PFD) (8th January 2026)
• Personal Locator Beacon (PLB) (25th October 2024)
• Personal Watercraft Proficiency (4th February 2025)
• Pile (25th October 2024)
• Pilot (25th October 2024)
• Pilot Book (30th August 2026)
• Pilotage (25th October 2024)
• Pinching (Sailing) (25th October 2024)
• Pipe Down (25th October 2024)
• Piston Hank (30th August 2026)
• Pitch (Vessel Motion) (25th October 2024)
• Pitchpole (4th June 2025)
• Plot (Navigation) (25th October 2024)
• Plough Anchor (30th August 2026)
• Plymouth (21st July 2025)
• Polar Diagram (8th October 2026)
• Pontoon (25th October 2024)
• Pooped (25th October 2024)
• Port (26th March 2025)
• Port (Harbour) (25th October 2024)
• Port Authority (30th August 2026)
• Port Beam (25th October 2024)
• Port Bow (25th October 2024)
• Port Limits (30th August 2026)
• Port of Registry (25th October 2024)
• Port Quarter (25th October 2024)
• Port State Control (30th August 2026)
• Port Tack (25th October 2024)
• Porthole (25th October 2024)
• Portland (21st July 2025)
• Portland Plotter (25th October 2024)
• Position Approximate (PA) (2nd September 2026)
• Position Dilution of Precision (PDOP) (25th October 2024)
• Position Doubtful (PD) (2nd September 2026)
• Positive Stability (30th August 2026)
• Powerboat Advanced (4th February 2025)
• Powerboat Intermediate (4th February 2025)
• Pratique (2nd January 2025)
• Precipitation (25th October 2024)
• Preliminary Notice (30th August 2026)
• Press Gangs (25th October 2024)
• Pressed into Service (25th October 2024)
• Pressure Gradient (30th August 2026)
• Prevailing Wind (25th October 2024)
• Prime Meridian (14th November 2024)
• Procedural Signal (30th August 2026)
• Procedure Words (Prowords) (20th July 2025)
• Professional Practices and Responsibilities (4th February 2025)
• Propeller (25th October 2024)
• Propeller Shaft (25th October 2024)
• Propeller Walk (25th October 2024)
• Propeller Wash (19th February 2025)
• Prow (7th July 2026)
• Pushpit (25th October 2024)
• Pyrotechnic Expiry (30th August 2026)
• Q Flag (Quebec) (25th October 2024)
• Quarter Berth (25th October 2024)
• Quebec (Phonetic Alphabet) (25th October 2024)
• Quick-flashing Light (Q) (2nd September 2026)
• Race Course (30th August 2026)
• Race Strategy (30th August 2026)
• Racing Rules of Sailing (25th October 2024)
• Racon (30th August 2026)
• Radar (25th October 2024)
• Radar and Radio Aid Abbreviations on Nautical Charts (2nd September 2026)
• Radar Marker Beacon (Ramark) (2nd September 2026)
• Radar Reflector (25th October 2024)
• Radio Medical Advice Link Call (15th January 2025)
• Radio Regulations (30th August 2026)
• Radiotelephony Spelling Alphabet (30th August 2026)
• Raft Up (25th October 2024)
• Raster Chart (25th October 2024)
• Raster Navigational Chart (30th August 2026)
• Reach (Point of Sail) (25th October 2024)
• Reaching (25th October 2024)
• Ready (Flag Semaphore) (26th October 2024)
• Ready About (25th October 2024)
• Ready to Receive (Flag Semaphore) (18th December 2024)
• Recovery Sling (30th August 2026)
• Red Light or Mark (R) (2nd September 2026)
• Reef (Underwater Feature) (25th October 2024)
• Reef Clew (30th August 2026)
• Reef Cringle (30th August 2026)
• Reef Knot (8th October 2026)
• Reef Tack (30th August 2026)
• Reefing (25th October 2024)
• Reefing Hook (25th October 2024)
• Reefing Lines (25th October 2024)
• Relative Bearing (30th August 2026)
• Relative Humidity (8th October 2026)
• Render a Line (30th August 2026)
• Reported Charted Feature (Rep) (2nd September 2026)
• Reserve Buoyancy (30th August 2026)
• Resistance (Vessel Motion) (8th October 2026)
• Rest (Flag Semaphore) (1st November 2024)
• Restricted in Ability to Manoeuvre (RAM) (25th October 2024)
• Restricted Visibility (25th October 2024)
• Rhumb Line (25th October 2024)
• Ride Height (30th August 2026)
• Riding Turn (25th October 2024)
• Rigging (25th October 2024)
• Rigging (25th October 2024)
• Rigging Screw (8th October 2026)
• Righting Lever (30th August 2026)
• Righting Moment (8th October 2026)
• Rigid Inflatable Boat (25th October 2024)
• Risk of Collision (25th October 2024)
• Roach (8th October 2026)
• Rock Seabed (R) (2nd September 2026)
• Rockall (21st July 2025)
• Rocket Parachute Flare (19th March 2025)
• Roll Tacking (8th October 2026)
• Roller Furling (25th October 2024)
• Roller Reefing (25th October 2024)
• Rolling Hitch (8th October 2026)
• Romeo (Phonetic Alphabet) (25th October 2024)
• Rope Clutch (7th March 2025)
• Rotary Tidal Stream (30th August 2026)
• Rotating-pattern Radiobeacon (RG) (2nd September 2026)
• Round Turn and Two Half Hitches (8th October 2026)
• Round Up (Sailing) (25th October 2024)
• Route (30th August 2026)
• Route Leg (30th August 2026)
• Routeing Abbreviations on Nautical Charts (2nd September 2026)
• Roving Fender (25th October 2024)
• Royal National Lifeboat Institution (RNLI) (25th October 2024)
• Royal Yachting Association (RYA) (24th February 2025)
• Rudder (25th October 2024)
• Rudder Bearing (30th August 2026)
• Rudder Stall (30th August 2026)
• Rudder Stock (25th October 2024)
• Rule 1: Application (25th October 2024)
• Rule 10: Traffic Separation Schemes (25th October 2024)
• Rule 11: Application (25th October 2024)
• Rule 12: Sailing vessels (25th October 2024)
• Rule 13: Overtaking (25th October 2024)
• Rule 14: Head-on situation (25th October 2024)
• Rule 15: Crossing situation (25th October 2024)
• Rule 16: Action by give-way vessel (25th October 2024)
• Rule 17: Action by stand-on vessel (25th October 2024)
• Rule 18: Responsibilities between vessels (25th October 2024)
• Rule 19: Conduct of vessels in restricted visibility (25th October 2024)
• Rule 2: Responsibility (25th October 2024)
• Rule 20: Application (25th October 2024)
• Rule 21: Definitions (25th October 2024)
• Rule 22: Visibility of lights (25th October 2024)
• Rule 23: Power-driven vessels underway (25th October 2024)
• Rule 24: Towing and pushing (25th October 2024)
• Rule 25: Sailing vessels underway and vessels under oars (25th October 2024)
• Rule 26: Fishing vessels (25th October 2024)
• Rule 27: Vessel not under command or restricted in their ability to manoeuvre (25th October 2024)
• Rule 28: Vessel constrained by their draught (25th October 2024)
• Rule 29: Pilot vessels (25th October 2024)
• Rule 3: General definitions (25th October 2024)
• Rule 30: Anchored vessels and vessels aground (25th October 2024)
• Rule 31: Seaplanes (25th October 2024)
• Rule 32: Definitions (25th October 2024)
• Rule 33: Equipment for sound signals (25th October 2024)
• Rule 34: Manoeuvring and warning signals (25th October 2024)
• Rule 35: Sound signals in restricted visibility (25th October 2024)
• Rule 36: Sound signals to attract attention (25th October 2024)
• Rule 37: Distress signals (25th October 2024)
• Rule 38: Exemptions (25th October 2024)
• Rule 39: Definitions (25th October 2024)
• Rule 4: Application (25th October 2024)
• Rule 40: Application (25th October 2024)
• Rule 41: Verification of Compliance (25th October 2024)
• Rule 5: Look-out (25th October 2024)
• Rule 6: Safe speed (25th October 2024)
• Rule 7: Risk of collision (25th October 2024)
• Rule 8: Action to avoid collision (25th October 2024)
• Rule 9: Narrow channels (25th October 2024)
• Run (Line Handling) (25th October 2024)
• Run Free (30th August 2026)
• Running (26th March 2025)
• Running Backstay (9th November 2024)
• Running Fix (25th October 2024)
• Running Rigging (25th October 2024)
• RYA DofE Centre (4th February 2025)
• RYA Handy Plotter (30th October 2025)
• RYA Training Almanac (25th October 2024)
• RYA Training Chart (25th October 2024)
• RYA/MCA Advanced Powerboat Exam (4th February 2025)
• RYA/MCA Yachtmaster Coastal Motor Exam (4th February 2025)
• RYA/MCA Yachtmaster Coastal Sail Exam (4th February 2025)
• RYA/MCA Yachtmaster Ocean Exam (4th February 2025)
• RYA/MCA Yachtmaster Offshore Motor Exam (4th February 2025)
• RYA/MCA Yachtmaster Offshore Sail Exam (4th February 2025)
• S-100 Universal Hydrographic Data Model (10th January 2025)
• S-101 (30th August 2026)
• S-57 (30th August 2026)
• Sacrificial Anode (25th October 2024)
• Safe and Fun Safeguarding (4th February 2025)
• Safe Speed (30th August 2026)
• Safe Water Mark (25th October 2024)
• Safety Boat (4th February 2025)
• Safety Knife (8th October 2026)
• Safety Tether (30th August 2026)
• Saffir–Simpson Hurricane Wind Scale (25th October 2024)
• Sail Balance (30th August 2026)
• Sail Locker (25th October 2024)
• Sail Slide (25th October 2024)
• Sail Ties (25th October 2024)
• Sail Trim (30th August 2026)
• Sail Twist (30th August 2026)
• Saildrive (25th October 2024)
• Saildrive (25th October 2024)
• Saildrive Diaphragm (30th August 2026)
• Sailing Directions (25th October 2024)
• Sailing Instructions (30th August 2026)
• Sailing-vessel Rule (30th August 2026)
• Salinity (25th October 2024)
• Saloon (25th October 2024)
• Sand Seabed (S) (2nd September 2026)
• Satellite Geometry (30th August 2026)
• Scope (25th October 2024)
• Scupper (25th October 2024)
• Sea Anchor (25th October 2024)
• Sea Breeze (25th October 2024)
• Sea Fastening (30th August 2026)
• Sea Legs (25th October 2024)
• Sea Room (30th August 2026)
• Sea State (30th August 2026)
• Seabed Abbreviations on Nautical Charts (2nd September 2026)
• Seacock (25th October 2024)
• Seamanship Skills (30th August 2026)
• Search and Rescue (SAR) (25th October 2024)
• Search and Rescue Region (30th August 2026)
• Search and Rescue Transponder (Radar SART) (19th February 2025)
• Seasickness (30th August 2026)
• Second Substitute (ICS Flag) (28th December 2024)
• Secondary Port (25th October 2024)
• Sector Light (25th October 2024)
• SÉCURITÉ (25th October 2024)
• Semaphore (1st November 2024)
• Semi-displacement Vessel (25th October 2024)
• Send (Sea Motion) (25th October 2024)
• Set (Current) (30th August 2026)
• Set an Anchor (25th October 2024)
• Set and Drift (30th August 2026)
• Set Sail (25th October 2024)
• Sextant (8th October 2026)
• Shackle (Rigging Fitting) (25th October 2024)
• Shaft Alignment (30th August 2026)
• Shaft Drive (25th October 2024)
• Shaft Drive (25th October 2024)
• Shaft Seal (30th August 2026)
• Shannon (21st July 2025)
• Sheet (Sail Control) (25th October 2024)
• Sheet Bend (8th October 2026)
• Sheet Lead (30th August 2026)
• Sheeting Angle (30th August 2026)
• Shells Seabed (Sh) (2nd September 2026)
• Shipping Lane (25th October 2024)
• Shipshape (25th October 2024)
• Shoal (25th October 2024)
• Shock Cord (25th October 2024)
• Shock Load (30th August 2026)
• Shorten Sail (25th October 2024)
• Shroud (Rigging) (25th October 2024)
• Side Deck (25th October 2024)
• Sidelight (30th August 2026)
• Sierra (Phonetic Alphabet) (25th October 2024)
• Signal Hoist (30th August 2026)
• Sill (25th October 2024)
• Silt Seabed (Si) (2nd September 2026)
• Single-line Reefing (30th August 2026)
• Skeg (25th October 2024)
• Sky Wave (30th August 2026)
• Slab Reefing (25th October 2024)
• Slack Off (25th October 2024)
• Slack Water (25th October 2024)
• Slamming (25th October 2024)
• Sliding Gooseneck (30th August 2026)
• Slip a Line (30th August 2026)
• Slip Knot (8th October 2026)
• Slip Lines (28th May 2025)
• Slip the Lines (28th May 2025)
• Slipway (25th October 2024)
• Sloop (25th October 2024)
• Slot (25th October 2024)
• Slot Effect (30th August 2026)
• Small Vessel Electronic Chart System (SVECS) (14th January 2025)
• Snap-back Zone (30th August 2026)
• Snatch (25th October 2024)
• Snug Down (25th October 2024)
• SOLAS Chapter V — Safety of Navigation (25th October 2024)
• Sole (Shipping Forecast Area) (25th October 2024)
• Sole Boards (25th October 2024)
• SOS (25th October 2024)
• Sou’wester (25th October 2024)
• Sound (Geographic Feature) (25th October 2024)
• Sounding (Depth) (25th October 2024)
• South on a Nautical Chart (S) (2nd September 2026)
• South Utsire (21st July 2025)
• Southeast Iceland (21st July 2025)
• Space (Flag Semaphore) (1st November 2024)
• Spar (Rigging) (25th October 2024)
• Speed Made Good (25th October 2024)
• Speed Over the Ground (SOG) (25th October 2024)
• Speed Through the Water (STW) (22nd August 2025)
• Spill Wind (25th October 2024)
• Spinnaker (25th October 2024)
• Spinnaker Gybe (30th August 2026)
• Spinnaker Pole (25th October 2024)
• Spit (25th October 2024)
• Splice (25th October 2024)
• Splice Taper (30th August 2026)
• Sportbootführerschein (24th February 2025)
• Sportbootführerschein Binnen (SBF Binnen) (24th February 2025)
• Sportbootführerschein See (SBF See) (24th February 2025)
• Sportküstenschifferschein (SKS) (24th February 2025)
• Sportsboat (25th October 2024)
• Spray Hood (25th October 2024)
• Spreader (Rigging) (25th October 2024)
• Spring Lines (25th October 2024)
• Spring Range (25th October 2024)
• Spring Tide (25th October 2024)
• Spring-neap Cycle (30th August 2026)
• Squall (25th October 2024)
• Square Sail (8th October 2026)
• Squat (30th August 2026)
• SSB Radio (8th October 2026)
• Stanchion (Guardrail) (25th October 2024)
• Stand by to Gybe (25th October 2024)
• Stand Off (25th October 2024)
• Stand On (25th October 2024)
• Stand-on Vessel (30th August 2026)
• Standard Port (25th October 2024)
• Standing Part (25th October 2024)
• Standing Part (25th October 2024)
• Standing Rigging (25th October 2024)
• Starboard (25th October 2024)
• Starboard Beam (25th October 2024)
• Starboard Bow (25th October 2024)
• Starboard Quarter (25th October 2024)
• Starboard Tack (25th October 2024)
• Start Motor Cruising (4th February 2025)
• Start Windsurfing (4th February 2025)
• Start Yachting (4th February 2025)
• Starting Sequence (30th August 2026)
• Starting Tactics (30th August 2026)
• Statute Mile (14th November 2024)
• Stay (25th October 2024)
• Staysail (8th October 2026)
• STCW (30th August 2026)
• Steady (25th October 2024)
• Steaming (25th October 2024)
• Steering Compass (25th October 2024)
• Steering Quadrant (8th January 2026)
• Stem (Hull) (25th October 2024)
• Stern (25th October 2024)
• Stern Drive (Inboard/Outboard) (25th October 2024)
• Stern Line (25th October 2024)
• Stern Spring (11th February 2025)
• Stern Tube (30th August 2026)
• Sternlight (25th October 2024)
• Sternway (30th August 2026)
• Stones Seabed (St) (2nd September 2026)
• Stopper Knot (25th October 2024)
• Storm (Beaufort Force 10) (25th October 2024)
• Storm Jib (25th October 2024)
• Storm Sail (30th August 2026)
• Storm Shutters (8th October 2026)
• Storm Surge (30th August 2026)
• Stove (25th October 2024)
• Stow (25th October 2024)
• Strong Point (30th August 2026)
• Superbuoy (25th October 2024)
• Surge (30th August 2026)
• Survival Craft (30th August 2026)
• Swashway (25th October 2024)
• Swinging Room (25th October 2024)
• Symmetric Spinnaker (29th September 2025)
• Synoptic Weather Chart (25th October 2024)
• Syzygy (1st June 2025)
• Tack (26th March 2025)
• Tack (Sailing Manoeuvre) (25th October 2024)
• Tack Determination (30th August 2026)
• Tacking (25th October 2024)
• Tacking Downwind (8th October 2026)
• Tacking Loss (30th August 2026)
• Take In a Sail (25th October 2024)
• Take the Helm (25th October 2024)
• Taking the Ground (30th August 2026)
• Tango (Phonetic Alphabet) (25th October 2024)
• Taut-line Hitch (8th October 2026)
• Telltales (25th October 2024)
• Temperature Inversion (8th October 2026)
• Temporary Notice (30th August 2026)
• Tender (25th October 2024)
• Tender Operator (4th February 2025)
• Thames (21st July 2025)
• The Royal Institution of Naval Architects (4th November 2024)
• Thermal Protective Aid (TPA) (8th October 2026)
• Third Substitute (ICS Flag) (28th December 2024)
• Three Sheets to the Wind (26th March 2025)
• Throat Halyard (30th August 2026)
• Tidal Datum (30th August 2026)
• Tidal Datum Abbreviations on Nautical Charts (2nd September 2026)
• Tidal Eddy (30th August 2026)
• Tidal Prediction (30th August 2026)
• Tidal Race (25th October 2024)
• Tidal Range (25th October 2024)
• Tidal Residual (30th August 2026)
• Tidal Stream (25th October 2024)
• Tidal Vector (30th August 2026)
• Tidal-stream Atlas (25th October 2024)
• Tidal-stream Rate (25th October 2024)
• Tide (25th October 2024)
• Tide Tables (25th October 2024)
• Tide-generating Force (30th August 2026)
• Tiller (25th October 2024)
• Time Dilution of Precision (TDOP) (25th October 2024)
• Time to Closest Point of Approach (TCPA) (25th October 2024)
• Time to Go (25th October 2024)
• Time Zone (25th October 2024)
• Time-expired Pyrotechnics (30th August 2026)
• Toe Rail (25th October 2024)
• Tomasz Schafernaker (25th October 2024)
• Topmark (30th August 2026)
• Topping Lift (25th October 2024)
• Topsail (8th October 2026)
• Topsides (25th October 2024)
• Trafalgar (21st July 2025)
• Traffic Lane (30th August 2026)
• Traffic Separation Scheme (TSS) (25th October 2024)
• Transducer (30th August 2026)
• Transducer Offset (30th August 2026)
• Transferred Position Line (30th August 2026)
• Transit (Navigation) (25th October 2024)
• Transom (25th October 2024)
• Transom Stern (30th August 2026)
• Traveller (Sail Control) (25th October 2024)
• Traveller Car (30th August 2026)
• Traveller Track (30th August 2026)
• Tri-colour Light (25th October 2024)
• Trim (Vessel and Sail) (25th October 2024)
• Trim by the Stern (30th August 2026)
• Trim Tabs (25th October 2024)
• Trimaran (25th October 2024)
• Trinity House (4th November 2024)
• Trip Line (30th August 2026)
• Trucker’s Hitch (8th October 2026)
• True Bearing (30th August 2026)
• True North (25th October 2024)
• True Wind (25th October 2024)
• Trysail (20th April 2026)
• Turbulent Flow (8th October 2026)
• Turn (25th October 2024)
• Tyne (21st July 2025)
• U.S. Coast Guard (14th November 2024)
• UK Hydrographic Office (UKHO) (11th February 2025)
• UK Shipping Forecast (25th October 2024)
• UK Variable-resolution Model (UKV) (10th November 2025)
• Ultra Quick-flashing Light (UQ) (2nd September 2026)
• Ultraviolet Radiation (UV) (25th October 2024)
• Uncovers (uncov) (2nd September 2026)
• Under the Weather (25th October 2024)
• Under Way (25th October 2024)
• Under-keel Clearance (30th August 2026)
• Underhand Loop (25th October 2024)
• Uniform (Phonetic Alphabet) (25th October 2024)
• Unintensified Light Sector (Unintens) (2nd September 2026)
• United Nations (15th November 2024)
• United States Naval Observatory (USNO) (11th February 2025)
• Unlucky Bananas (25th October 2024)
• Upwind (30th August 2026)
• User Equivalent Range Error (30th August 2026)
• UT1 (30th August 2026)
• UV Index (8th October 2026)
• Vector Nautical Chart (25th October 2024)
• Velocity Made Good (VMG) (25th October 2024)
• Vertical Datum (30th August 2026)
• Vertical Dilution of Precision (VDOP) (25th October 2024)
• Very High Frequency (VHF) (25th October 2024)
• Very Quick-flashing Light (VQ) (2nd September 2026)
• Vessel (25th October 2024)
• Vessel at Anchor (30th August 2026)
• Vessel Traffic Service (VTS) (24th February 2025)
• Victor (Phonetic Alphabet) (25th October 2024)
• Victualling (25th October 2024)
• Viking (21st July 2025)
• Violent Storm (25th October 2024)
• Wake (25th October 2024)
• Warp (Line) (25th October 2024)
• Wash (Vessel-generated Waves) (25th October 2024)
• Washboards (25th October 2024)
• Watch (Duty Period) (25th October 2024)
• Watch Handover (30th August 2026)
• Watchkeeping (30th August 2026)
• Water Depth (25th October 2024)
• Water Ingress (30th August 2026)
• Water Track (25th October 2024)
• Waterproof Torch (8th October 2026)
• Watertight (30th August 2026)
• Way (Vessel Motion) (25th October 2024)
• Waypoint (25th October 2024)
• Weather Deck (30th August 2026)
• Weather Forecast (30th August 2026)
• Weather Helm (25th October 2024)
• Weathertight (30th August 2026)
• Weed Seabed (Wd/Wds) (2nd September 2026)
• Weigh Anchor (25th October 2024)
• West on a Nautical Chart (W) (2nd September 2026)
• Wet Locker (30th August 2026)
• Wheel (Steering) (25th October 2024)
• Whipping (Ropework) (25th October 2024)
• Whisker Pole (25th October 2024)
• Whiskey (Phonetic Alphabet) (25th October 2024)
• White Horses (25th October 2024)
• White Light or Mark (W) (2nd September 2026)
• Whole Gale (25th October 2024)
• Wight (21st July 2025)
• Winch (Marine) (25th October 2024)
• Winch Handle (25th October 2024)
• Winch Override (30th August 2026)
• Wind Chill (8th October 2026)
• Wind Triangle (30th August 2026)
• Windage (25th October 2024)
• Windsurfing (30th August 2026)
• Windsurfing Advanced Racing (4th February 2025)
• Windsurfing Foiling First Flights (4th February 2025)
• Windsurfing Foiling Performance Flights (4th February 2025)
• Windsurfing Foiling Sustained Flights (4th February 2025)
• Windsurfing Intermediate Racing (4th February 2025)
• Windsurfing Start Racing (4th February 2025)
• Windward (25th October 2024)
• Wingfoiling First Flights (4th February 2025)
• Wingfoiling Sustained Flights (4th February 2025)
• Working End (25th October 2024)
• Working Load (30th August 2026)
• Working Load Limit (30th August 2026)
• World Geodetic System 1984 (WGS 84) (25th October 2024)
• World Meteorological Organization (WMO) (10th November 2025)
• World Radiocommunication Conference (30th August 2026)
• World Sailing (25th October 2024)
• Wreck (Wk) (2nd September 2026)
• X-ray (Phonetic Alphabet) (25th October 2024)
• Yacht (25th October 2024)
• Yachtmaster Ocean Theory (4th February 2025)
• Yachtsman's Gale (25th October 2024)
• Yankee (Phonetic Alphabet) (25th October 2024)
• Yard (Spar) (25th October 2024)
• Yawl (Sailing Rig) (25th October 2024)
• Youth Sailing Scheme - Start Sailing Stage 1 (4th February 2025)
• Youth Sailing Scheme - Start Sailing Stage 2 (4th February 2025)
• Youth Sailing Scheme - Start Sailing Stage 3 (4th February 2025)
• Youth Sailing Scheme - Start Sailing Stage 4 (4th February 2025)
• Youth Sailing Scheme Start Racing (4th February 2025)
• Youth Windsurfing Stage 1 (4th February 2025)
• Youth Windsurfing Stage 2 (4th February 2025)
• Youth Windsurfing Stage 3 (4th February 2025)
• Youth Windsurfing Stage 4 (4th February 2025)
• Zephyr (8th October 2026)
• Zulu (Phonetic Alphabet) (25th October 2024)