Sources
Where every fact comes from
Teaching text on this site is original. These are the public sources each fact was checked against.
Every fact taught on the site is listed here with the source it came from. Teaching text is original wording; nothing is copied from a paid course or from RYA course books. Game physics numbers are tuned teaching approximations, sourced where real.
Sources
| id | Source | URL | Read |
|---|---|---|---|
| S1 | RYA Day Skipper Theory course syllabus (17 sections), as reproduced by Classic Sailing | https://classic-sailing.co.uk/article/rya-day-skipper-theory-syllabus | 2026-10-05 |
| S2 | IALA, Maritime Buoyage System booklet (2010 revision), via Commissioners of Irish Lights | https://www.irishlights.ie/media/11141/IALA-MBS.pdf | 2026-10-05 |
| S3 | Wikipedia, Cardinal mark (table of topmarks, colours, light rhythms; cites IALA) | https://en.wikipedia.org/wiki/Cardinal_mark | 2026-10-05 |
| S4 | Wikipedia, Glossary of nautical terms (A–L) and (M–Z) | https://en.wikipedia.org/wiki/Glossary_of_nautical_terms_(A%E2%80%93L) | 2026-10-05 |
| S5 | Lagoon, Lagoon 42 specifications (LOA 12.80 m, beam 7.70 m, draft 1.25 m, 2 engines) | https://www.catamarans-lagoon.com/boats/lagoon-42 | 2026-10-05 |
| S6 | MDL Marinas, Beneteau Oceanis 40.1 (LOA 12.87 m, beam 4.18 m, draught 2.17 m) | https://www.mdlmarinas.co.uk/south-coast-virtual-boat-show/exhibitors/beneteau-sail/beneteau-oceanis-40-1/ | 2026-10-05 |
| S7 | MCA, MSN 1781 — the COLREGs as applied in the UK (Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations 1996) | https://www.gov.uk/government/publications/msn-1781-distress-signals-and-preventing-collisions | 2026-10-05 |
| S8 | Met Office, Beaufort wind force scale | https://weather.metoffice.gov.uk/guides/coast-and-sea/beaufort-scale | 2026-10-05 |
| S9 | Met Office, Marine forecast glossary (gale, severe gale, imminent/soon/later) | https://weather.metoffice.gov.uk/guides/coast-and-sea/glossary | 2026-10-05 |
| S10 | Motor Boat & Yachting, Jon Mendez, How to mark your anchor chain — "all chain, four times the depth; chain and warp, six times" (also the numbers fixed in the brief). Corrected 2026-10-05: YachtBuyer's page gives 5:1–7:1, so it is no longer cited for 4×/6× | https://www.mby.com/video/how-to-mark-your-anchor-chain-6-top-tips-from-our-expert-132417 | 2026-10-05 |
| S13 | Wikipedia, Anchor — small-boat anchor types (CQR/plough, Delta, Danforth/fluke, Bruce/claw, scoop/roll-bar) and their strengths | https://en.wikipedia.org/wiki/Anchor | 2026-10-05 |
| S14 | Multihulls World, Anchoring: all you need to know about bridles — a bridle reduces sheering and takes the load off the windlass | https://www.multihulls-world.com/practical-catamaran-trimaran/anchoring-all-you-need-to-know-about-bridles | 2026-10-05 |
| S16 | Wikipedia, Mooring — a typical mooring scheme: head (bow) line, breast lines, springs, stern line and what each does | https://en.wikipedia.org/wiki/Mooring_(watercraft) | 2026-10-05 |
| S15 | YachtBuyer, The Art of Anchoring — choosing an anchorage (holding ground, shelter, depth), anchor watch (transits, GPS anchor alarm), chart abbreviations | https://www.yachtbuyer.com/en-gb/advice/the-art-of-anchoring | 2026-10-05 |
| S17 | Wikipedia, Rope — laid (three-strand, usually right-laid) and braided construction, core-and-cover (kernmantle) ropes, nylon / polyester / polypropylene / HMPE properties | https://en.wikipedia.org/wiki/Rope | 2026-10-05 |
| S18 | RNLI, Choose it, wear it: an RNLI guide to lifejackets and buoyancy aids (levels 50/100/150/275, manual / water-activated / hydrostatic firing, crotch straps, spray hood, light and whistle, monthly checks and annual service) — leaflet copy hosted by ADEC Marine | https://www.adecmarine.co.uk/files/ww/rnli.LeisLifejacketLeaflet-LR.pdf | 2026-10-05 |
| S19 | Crewsaver, Care, maintenance & servicing — your questions answered (annual service; cylinder minimum weight, corrosion, charge marked on the bladder; leak test; toggle accessible) | https://crewsaver.com/lifejacketsafe/care-maintenance-servicing-your-questions-answered | 2026-10-05 |
| S20 | RYA, Distress flares (parachute rocket ~300 m / ~40 s, not near a helicopter; red handheld ~1 min, a few miles, held downwind, outboard, tilted away; orange smoke daylight only, ~3 min; white flare for collision warning; storage and expiry) | https://www.rya.org.uk/knowledge/safety/look-after-yourself/equipment-for-uk-pleasure-vessels/distress-flares | 2026-10-05 |
| S21 | Wikipedia, Fire extinguisher — BS EN 3 fire classes A, B, C, D, F; UK colour bands water red, foam cream, dry powder blue, CO2 black, wet chemical yellow, and the classes each suits | https://en.wikipedia.org/wiki/Fire_extinguisher | 2026-10-05 |
| S22 | Cornwall Fire and Rescue Service, Kitchen fires — pan fire: heat off if safe without leaning over, fire blanket over the pan, never water, no extinguisher, don't move the pan | https://www.cornwall.gov.uk/fire-and-rescue-service/keeping-safe/fire-safety/fire-safety-at-home/kitchen-fires/ | 2026-10-05 |
| S23 | RYA, Guide to gas safety on boats — gas is denser than air and sinks; bottles upright in a locker draining overboard; off at the cylinder; gas alarm sensors where gas collects; suspected-leak drill; never test with a flame | https://www.rya.org.uk/water-safety/gas-safety-on-boats | 2026-10-05 |
| S24 | Practical Boat Owner, Is it safe to use a tether? — clip on to the windward jackstay with a short tether; shorter is better | https://www.pbo.co.uk/seamanship/is-it-safe-to-use-a-tether-25125 | 2026-10-05 |
| S25 | Yachting Monthly, Where should you stow your liferaft? — only step up into a liferaft; stowage options; never below deck; painter tied to a strongpoint | https://www.yachtingmonthly.com/gear/where-should-you-stow-your-liferaft-51442 | 2026-10-05 |
| S26 | MCA, MGN 343 — hydrostatic release units: raft floats free, pulls out the painter, painter at full length fires the gas cylinder, weak link breaks | https://www.gov.uk/government/publications/mgn-343-hydrostatic-release-units-stowage-and-arrangements-for-liferafts | 2026-10-05 |
| S27 | Wikipedia, Liferaft — canister stowage, hydrostatic release, periodic servicing, liferafts are not self-righting | https://en.wikipedia.org/wiki/Liferaft | 2026-10-05 |
| S28 | World Sailing Offshore Special Regulations, multihull extract (via Sail Canada) — jackstay definition, jackstays independent each side and clip on before coming on deck; escape hatch in each accommodation hull above water when inverted, on a catamaran on the side nearest the centreline; liferaft deployable whether or not inverted; fire blanket next to the cooker | https://www.sailing.ca/wp-content/uploads/2024/12/sc_osr2024-2025_mu1.pdf | 2026-10-05 |
| S29 | Wikipedia, Nautical mile — international nautical mile exactly 1,852 m; historically one minute of latitude; the knot is one nautical mile per hour | https://en.wikipedia.org/wiki/Nautical_mile | 2026-10-05 |
| S30 | Wikipedia, Geographic coordinate system — latitude 0–90° N/S of the equator, longitude 0–180° E/W of the Greenwich prime meridian; parallels and meridians; degree = 60 minutes | https://en.wikipedia.org/wiki/Geographic_coordinate_system | 2026-10-05 |
| S31 | Wikipedia, Mercator projection — nautical charts carry a latitude scale from which meridian distance is read; scale grows away from the equator; rhumb lines are straight | https://en.wikipedia.org/wiki/Mercator_projection | 2026-10-05 |
| S32 | Wikipedia, Nautical chart — depths from chart datum (trend to LAT), in metres on modern charts; heights referred to MHWS; Chart 1 / INT 1 symbols; correction by Notices to Mariners | https://en.wikipedia.org/wiki/Nautical_chart | 2026-10-05 |
| S33 | Wikipedia, Chart datum — LAT is the lowest tide predicted under average conditions | https://en.wikipedia.org/wiki/Chart_datum | 2026-10-05 |
| S34 | UKHO, Chart 5011 — Symbols and abbreviations used on ADMIRALTY charts (INT 1 format, ed. 4, 2008; public copy) — underlined figures are drying heights above chart datum; seabed S, M, Sh, R; Wk; danger line; light characteristics | https://saillavie.co.il/wp-content/uploads/securepdfs/2020/05/Chart-5011.pdf | 2026-10-05 |
| S35 | UKHO / ADMIRALTY, Keeping charts up to date (leisure editions) — fine magenta pen, Chart 5011, weekly leisure NMs; insert new before deleting, two diagonal lines through the old symbol; colour blocks cut and glued; note NM number and year bottom left; note non-applicable NMs too | https://assets.admiralty.co.uk/public/2021-11/Keeping%20ADMIRALTY%20Leisure%20Charts%20up-to-date.pdf | 2026-10-05 |
| S36 | Wikipedia, Notice to mariners — UK NMs published weekly by the UKHO, formatted for correcting charts and publications | https://en.wikipedia.org/wiki/Notice_to_mariners | 2026-10-05 |
| S37 | Wikipedia, Breton plotter — ruler with a rotating protractor used as a compass rose, aligned with the chart's north | https://en.wikipedia.org/wiki/Breton_plotter | 2026-10-05 |
| S38 | RYA shop, Reeds Nautical Almanac 2026 — annual; harbour chartlets, tide tables and streams, buoyage and lights, waypoints, passage notes, distance tables, radio, weather and safety information | https://www.rya.org.uk/products/reeds-nautical-almanac-2026/ | 2026-10-05 |
| S39 | Wikipedia, Sailing directions — hazards, buoyage, pilotage, regulations, anchorages, port facilities, photos for identification | https://en.wikipedia.org/wiki/Sailing_directions | 2026-10-05 |
| S40 | Wikipedia, Bearing (angle) — clockwise from north 0–359°, true north reference, reciprocal 180° apart; Wikipedia, Cable length — one tenth of a nautical mile | https://en.wikipedia.org/wiki/Bearing_(angle) | 2026-10-05 |
| S41 | Wikipedia, Magnetic declination — angle between magnetic north and true north; East/West; changes slowly over time; shown on charts by compass roses with the annual change | https://en.wikipedia.org/wiki/Magnetic_declination | 2026-10-05 |
| S42 | Wikipedia, Magnetic deviation — compass error from nearby ferrous material or electrical equipment (also tools, other compasses); varies with the craft's heading; swinging on several headings; corrector magnets and soft iron; residual recorded on a correction card | https://en.wikipedia.org/wiki/Magnetic_deviation | 2026-10-05 |
| S43 | Wikipedia, Compass — lubber line shows the heading on the card; keep magnets and electronics away; ship's compass corrected for deviation from iron and steel on board | https://en.wikipedia.org/wiki/Compass | 2026-10-05 |
| S44 | Wikipedia, Hand compass — hand bearing compass used by small-boat sailors to take bearings of landmarks; floating card and sighting prism; illuminated dial | https://en.wikipedia.org/wiki/Hand_compass | 2026-10-05 |
| S45 | Sailing Issues navigation course, ch. 3 Compass — compass + deviation + variation = true with East positive; deviation from engine, anchor, plotters and wiring, varies with heading, deviation table; rose shows variation, year and annual change (e.g. 4°15'W 2009 (8'E)); hand bearing compass needs no deviation correction, apply variation only | https://www.sailingissues.com/navcourse3.html | 2026-10-05 |
| S46 | Savvy Navvy, Variation and deviation explained — TVMDC "True Virgins Make Dull Company"; "Error West compass best, error East compass least"; CADET, Compass to True Add East | https://www.savvy-navvy.com/blog/variation-and-deviation-explained | 2026-10-05 |
| S47 | Sailing Issues navigation course, ch. 7 Tidal predictions — chart datum (LAT in tidal waters) for soundings; MHWS, MLWS, MHWN, MLWN; observed depth = charted depth + height of tide; underlined sounding = drying height above datum; range = HW − LW; standard ports give daily HW/LW times and heights; tidal curve method (range, diagonal from LW to HW height, times from HW, time → curve → diagonal → height); keep at least 1 m under the keel, more for waves and swell | https://www.sailingissues.com/navcourse7.html | 2026-10-06 |
| S48 | Wikipedia, Chart datum — water surface that is the origin of charted depths and tide heights; UKHO uses LAT (lowest tide predictable under average meteorological conditions); charted depths and drying heights given relative to datum; depth = charted depth + height of tide; MHWS, MLWS | https://en.wikipedia.org/wiki/Chart_datum | 2026-10-06 |
| S49 | Sailing Issues navigation course, ch. 6 Tides — springs at full and new moon (large range), neaps at the quarter moons (small range); springs lag about 36–48 h after full/new moon; neaps about 7 days after springs | https://www.sailingissues.com/navcourse6.html | 2026-10-06 |
| S50 | Wikipedia, Tide — springs when sun, moon and Earth are in line, neaps when sun and moon are 90° apart; about seven days between springs and neaps; springs: higher highs, lower lows, stronger streams; range = difference between HW and LW; most coasts two HW and two LW a day, about 12 h 25 min apart | https://en.wikipedia.org/wiki/Tide | 2026-10-06 |
| S51 | Wikipedia, Rule of twelfths — 1:2:3:3:2:1 twelfths of the range per hour; assumes about six hours LW→HW and a sine-shaped curve; rough approximation only; fails where there are double high or low waters (Poole Harbour, the Solent, Weymouth Bay) | https://en.wikipedia.org/wiki/Rule_of_twelfths | 2026-10-06 |
| S52 | Sailing Issues navigation course, ch. 7 Tidal predictions (secondary ports) — secondary ports have time and height differences from a standard port in a tidal difference table; time differences depend on the standard port's HW/LW time, height differences on springs/neaps; interpolate linearly between the table's figures (fraction × change in difference + lower difference); use the standard port's tidal curve for heights between LW and HW | https://www.sailingissues.com/navcourse7.html | 2026-10-06 |
| S53 | Sailing Issues navigation course, ch. 8 Tidal streams and currents — tidal diamonds: magenta letter in a rhombus on the chart; table of 13 rows (HW−6 … HW … HW+6 at a standard port) with direction in degrees true and spring and neap rates in knots; "Dir" is the direction the stream flows towards; tidal stream atlas: 12 or 13 chartlets, one per hour, arrows for direction, thicker = stronger, rate pairs in tenths of knots neaps,springs (e.g. 37,52 = 3.7 kn neaps, 5.2 kn springs); interpolate between neaps and springs with the atlas's interpolation chart (or a rule of thumb); set = direction of a tidal stream, drift = its rate | https://www.sailingissues.com/navcourse8.html | 2026-10-06 |
| S54 | Wikipedia, Tidal diamond — symbols on Admiralty charts giving the direction and speed of tidal streams; 13-row table referred to HW at a standard port, bearing and spring/neap rates in knots; each tidal hour runs from half an hour before to half an hour after its nominal time (HW+3 row valid HW+2½ to HW+3½); rates between neaps and springs found by interpolation, traditionally on a "calculation of rates" chart; a tidal atlas is the alternative | https://en.wikipedia.org/wiki/Tidal_diamond | 2026-10-06 |
| S55 | Sailing Issues navigation course, ch. 4 Plotting and piloting — dead reckoning: apply to the last charted position the true courses and speed (distance) through the water, never over the ground; leeway: degrees by which a yacht is pushed off course to leeward by the wind; course to steer = water track ± leeway (add if the wind is from starboard, subtract if from port), then variation, then deviation last; cross-bearing fix: optimum spread 90° for two objects, 120° for three; a third position line usually forms a triangle, showing error in at least one bearing; near a danger assume the position closest to it; fix more reliable than an EP, EP more reliable than DR; a route is an ordered list of waypoints | https://www.sailingissues.com/navcourse4.html | 2026-10-06 |
| S56 | Wikipedia, Position fixing — a visual fix from bearings of two or more charted objects; three position lines generally form a triangle, the "cocked hat", and a small one gives confidence; most accurate when position lines cross at right angles; satellite receivers compute fixes from many satellites; fixes confirm a dead-reckoning position | https://en.wikipedia.org/wiki/Position_fixing | 2026-10-06 |
| S57 | Wikipedia, Daggerboard — a daggerboard converts forward motion into a windward lift, countering the leeward push of the sails; it can be raised in shallow water; used on catamarans | https://en.wikipedia.org/wiki/Daggerboard | 2026-10-06 |
| S58 | Wikipedia, Piloting — two features visually in line make a transit; a transit is not affected by compass accuracy and is often used to check a compass; pairs of daymarks form a leading line along which to navigate safely (leading lights when lit); depth from a sounder identifies a contour; "pilots" / UKHO Sailing Directions help coastal mariners | https://en.wikipedia.org/wiki/Piloting | 2026-10-06 |
| S59 | Wikipedia, Leading lights — a pair of beacons marking a safe passage into a shallow or dangerous channel; the front is lower than the rear; on the correct bearing they line up vertically; unlit, the pair is a transit (UK); for a turn, line up the next pair | https://en.wikipedia.org/wiki/Leading_lights | 2026-10-06 |
| S60 | Wikipedia, Sector light — strictly bounded horizontal beams guide traffic through a safe channel at night; white = middle of the safe channel, red = port edge, green = starboard edge for vessels approaching the light; sector bearings in degrees true as observed from sea; the colour changes, the characteristic does not | https://en.wikipedia.org/wiki/Sector_light | 2026-10-06 |
| S61 | Wikipedia, Sailing Directions — published by national hydrographic offices to support port entry and coastal navigation: hazards, buoyage, pilotage, regulations, anchorages, port facilities, with diagrams and photos; they provide the local knowledge a pilot would | https://en.wikipedia.org/wiki/Sailing_Directions | 2026-10-06 |
| S62 | Wikipedia, Light characteristic — the properties that identify a navigational light (sequence, colour, period); Fl, LFl, Oc, Iso, Q; Fl(3) = group of three flashes; "Fl(3) 15s 21m 12M" = three flashes every 15 s, light 21 m high, range 12 M | https://en.wikipedia.org/wiki/Light_characteristic | 2026-10-06 |
| S63 | Wikipedia, Shipping Forecast — produced by the Met Office, broadcast by BBC Radio 4 on behalf of the MCA; 31 sea areas listed clockwise round Britain (Viking, North/South Utsire, Forties … Dover, Wight, Portland, Plymouth … Fastnet, Rockall, Malin … Southeast Iceland); bulletin order gale warnings, general synopsis, area forecasts (wind, weather, visibility) | https://en.wikipedia.org/wiki/Shipping_Forecast | 2026-10-06 |
| S64 | Met Office, Inshore waters forecast — coastal waters up to 12 miles offshore round the British Isles in 19 areas; issued 0000, 0600, 1200, 1800 UTC, each valid 24 h; wind direction and force, weather, visibility, sea state; force 6+ highlighted | https://weather.metoffice.gov.uk/guides/coast-and-sea/inshore-waters-forecast | 2026-10-06 |
| S65 | MCA / HM Coastguard, Maritime safety information leaflet — HMCG broadcasts MSI on NAVTEX, VHF and MF; NAVTEX 518 kHz and 490 kHz to 270 M (gale warnings, 24-h forecast and outlook, navigation warnings); VHF announced on Ch 16 then broadcast on Ch 62, 63 or 64, range about 30 miles; inshore waters forecast and gale/strong wind warnings every three hours; strong wind warning when force 6 or more is forecast in an inshore area | https://www.gov.uk/government/publications/maritime-safety-information-leaflet/maritime-safety-information-leaflet | 2026-10-06 |
| S66 | Katamarans (catamaran news and marketplace site), Catamaran mainsail reefing — "A monohull warns you it is overpowered by heeling. A catamaran does not"; reef before you need to; if you are asking whether it is time, it is. (Its 15–20 / 20–25 / 25–30 kn bands are NOT used: not a maker's or charter company's table) | https://www.katamarans.com/catamaran-mainsail-reefing/ | 2026-10-06 |
| S67 | Wikipedia, Beaufort scale — knot ranges for forces 0–12 (<1, 1–3, 4–6, 7–10, 11–16, 17–21, 22–27, 28–33, 34–40, 41–47, 48–55, 56–63, ≥64) and sea descriptions (mirror, ripples, wavelets, crests begin to break, white horses, foam streaks, spindrift, dense streaks, sea white, air filled with foam and spray) | https://en.wikipedia.org/wiki/Beaufort_scale | 2026-10-06 |
| S68 | Royal Meteorological Society, How to interpret a weather chart — wind clockwise round a high and anticlockwise round a low (NH); Buys Ballot: back to the wind, lower pressure on the left; closer isobars = windier; wind almost parallel to isobars; highs fine, light winds, little cloud (descending air); lows rising air, cloud and rain, unsettled wet and windy; warm front red semicircles, cold front blue triangles, cold front narrow band of rain, sometimes heavy and thundery, then clearer with showers | https://www.rmets.org/metmatters/how-interpret-weather-chart | 2026-10-06 |
| S69 | Wikipedia, Warm front — cloud sequence cirrus → cirrostratus → altostratus/altocumulus → nimbostratus; high cloud spreading with pressure falling = precipitation about 6–8 h away; persistent rain during passage, drizzle after; NH wind backs before and veers after (SE to SW); warming; visibility poor before and during | https://en.wikipedia.org/wiki/Warm_front | 2026-10-06 |
| S70 | Wikipedia, Cold front — narrow band of precipitation along the leading edge; cumulonimbus and thunderstorms; NH wind veers SW to NW; pressure rises sharply then steadies; temperature drops; sky clears behind; visibility good except in showers; moves faster than warm fronts with sharper changes | https://en.wikipedia.org/wiki/Cold_front | 2026-10-06 |
| S71 | Wikipedia, Sea breeze — land heats faster than water; sea breeze blows in the afternoon from the sea onto the land, return flow aloft; develops after sunrise; land breeze at night because land cools faster, shallower than the sea breeze; extends 10–100 km from the coastline; cumulus over land marks the sea-breeze front | https://en.wikipedia.org/wiki/Sea_breeze | 2026-10-06 |
| S72 | Met Office, Fog — fog = visibility below 1,000 m; radiation fog usually in winter with clear skies and calm conditions, dissipates soon after sunrise as the ground warms; advection fog when moist warm air passes over a colder surface and is cooled, can be carried over coastal land, frequent on the UK east coast in spring and summer | https://weather.metoffice.gov.uk/learn-about/weather/types-of-weather/fog | 2026-10-06 |
| S73 | MCA / HM Coastguard, GMDSS: VHF DSC procedures for small boat users — distress "only to be used in the event of grave and imminent danger and assistance is required"; DSC alert: press and hold the button until the alert is sent, then on acknowledgement or after about 15 s transmit the distress call and message on Channel 16; voice format Mayday ×3, This is, name ×3, call sign, MMSI, Mayday, name/call sign/MMSI, position (preferably lat/long), nature of distress, assistance required, number of persons on board, other information, Over; urgency format Pan pan ×3, All stations ×3, This is name ×3, call sign, MMSI, working channel; safety: individual DSC call with safety priority to HMCG, else voice on 16; channel 13 bridge-to-bridge | https://www.gov.uk/government/publications/gmdss-sea-areas-and-procedures-for-small-boat-users/gmdss-vhf-dsc-procedures-for-small-boat-users | 2026-10-06 |
| S74 | RYA, Maydays and pan pan — Mayday for "grave and imminent danger to a vessel or persons, such as fire, sinking, man overboard"; three parts (DSC alert, voice call, message); red button, most models send GPS location; MMSI a nine-digit number identifying the boat; pan pan: no red button, send a DSC urgency call then voice on 16; keep a Mayday cockpit card by the radio; SRC is the minimum qualification required by law to operate VHF and VHF DSC on a British-flagged vessel | https://www.rya.org.uk/blog/maydays-and-pan-pan | 2026-10-06 |
| S75 | Wikipedia, Marine VHF radio and Channel 16 VHF — power limited to 25 W; 1–25 W; ~60 nmi between tall aerials, ~5 nmi between small boats at sea level; fixed sets have more power, a better aerial, bigger display; press-to-talk turns transmitter on and receiver off; ship-to-ship simplex; Over = finished, awaiting reply, Out = end; identify on 16 then switch to a working channel; ch 16 international distress, safety and calling, monitored 24 h by many coastguards; ch 70 DSC only; ch 13 bridge-to-bridge, vessels >20 m keep watch, 1 W; ch 6 intership; ch 67 UK Small Ship Safety Channel; SRC minimum to use an installed set, ~2-day course and exam; installations need a Ship Radio Licence | https://en.wikipedia.org/wiki/Marine_VHF_radio | 2026-10-06 |
| S76 | Wikipedia, Line-of-sight propagation — VHF needs a clear path between aerials; radio horizon d (km) ≈ 4.12 √h (m) with normal refraction; range grows with aerial height | https://en.wikipedia.org/wiki/Line-of-sight_propagation | 2026-10-06 |
| S77 | Wikipedia, Digital selective calling — calls set up on VHF channel 70, monitored continuously by DSC equipment; distress buttons under protective (often spring-loaded) covers; alert includes the MMSI; set may be connected to GPS so it knows who, when and where; repeats the alert if unacknowledged; operators must cancel false alerts | https://en.wikipedia.org/wiki/Digital_selective_calling | 2026-10-06 |
| S78 | Wikipedia, Maritime Mobile Service Identity — nine digits; first three are the Maritime Identification Digits (country code); issued by the flag state | https://en.wikipedia.org/wiki/Maritime_Mobile_Service_Identity | 2026-10-06 |
| S79 | Wikipedia, Mayday, Pan-pan and Sécurité — Mayday said three times, from French m'aider; false distress call a criminal offence in many countries; pan-pan: urgent, no immediate danger to life or vessel, from panne; examples engine failure safe from collision, medical advice, uncertain position without stranding risk; Sécurité said three times, navigational and meteorological warnings, call on 16 then a working channel for the message; order Mayday > Pan-pan > Sécurité | https://en.wikipedia.org/wiki/Mayday | 2026-10-06 |
| S80 | ITU, Resolution 349 (Rev. WRC-23) — cancelling false VHF DSC distress alerts: follow the screen or switch off/on after 10 s; self-cancel if the set can; set to channel 16; broadcast to "All Stations" ×3, "This is", name ×3, call sign, MMSI, "Please cancel my distress alert of" + time UTC | https://itu.int/en/ITU-R/terrestrial/fmd/Documents/WRC_23_Resolutions/E/RES_349(REV.WRC-23)-E.pdf | 2026-10-06 |
| S81 | Ofcom, Ship radio and ship portable radio — a licence is required; failure to hold one is a criminal offence; every new licence gets an MMSI which stays with the vessel for life; licences valid for the vessel's lifetime, not transferable to a new owner; apply/surrender through the online licensing portal; separate ship portable radio licence | https://www.ofcom.org.uk/spectrum/radio-equipment/ships-radio | 2026-10-06 |
| S82 | Icom, IC-M45A VHF marine transceiver instruction manual — dual watch monitors channel 16 while receiving a channel of your choice, tri-watch adds the call channel; high/low power switch, high power cannot be selected on some channels; push and hold PTT to transmit; you must identify yourself when you transmit | https://www.rigpix.com/marine/icom_icm45a_manual.pdf | 2026-10-06 |
| S83 | Practical Boat Owner, Man overboard turns: getting back to the casualty in the water — shout, press MOB on the GPS, Mayday on VHF, throw lifebuoy and danbuoy, one person watches and keeps pointing; RYA reach-tack-reach with a close-reach approach (sheet in to speed up, let flap to stop) and the casualty on the leeward side; RORC quick-stop variant with a gybe; check no ropes over the side near the stern before starting the engine | https://www.pbo.co.uk/seamanship/man-overboard-turns-getting-back-to-the-casualty-in-the-water-104939 | 2026-10-06 |
| S84 | Wikipedia, Man overboard — shout repeated by every crew member; one person only stands and points; throw flotation; plotter MOB button records the position; Quick Stop (tack without handling the jib sheets → hove to; if too far, sheet main, circle, gybe, back downwind, round up); Reach-Turn-Reach (beam reach away, tack or gybe, close-reach approach, luff up close); check for trailing ropes before engaging the engine; recover as horizontally as possible | https://en.wikipedia.org/wiki/Man_overboard | 2026-10-06 |
| S85 | Yachting Monthly, James Stevens, Can you get the MOB back on the boat? — release of hydrostatic pressure on the circulation after long immersion; short immersion: speed matters more; main halyard alone is hard work; rescue sling with a handy billy on the main halyard; bowline led to a winch to climb; stern ladder quick but dangerous in a big sea; parbuckling with a sail unlikely on a windy day | https://www.yachtingmonthly.com/sailing-skills/can-you-get-the-mob-back-on-the-boat-72018 | 2026-10-06 |
| S86 | Wikipedia, Cold shock response — below ~15 °C; gasp reflex (inhalation if underwater), hyperventilation; initial phase first 2–3 minutes; hypothermia after ~30 min; circum-rescue collapse immediately before, during or after rescue | https://en.wikipedia.org/wiki/Cold_shock_response | 2026-10-06 |
| S87 | Yachting Monthly, Rachael Sprot, Catamaran sailing skills: recover a multihull man overboard — catamarans don't heel; high topsides; the sugar scoop may be the only way back aboard; propellers further outboard and closer to the surface, engines off or at least in neutral; large blind spots need someone on the side deck; boathook essential; dinghy on davits or liferaft to help the transfer | https://www.yachtingmonthly.com/sailing-skills/catamaran-skills-recover-a-multihull-man-overboard-92126 | 2026-10-06 |
| S88 | Motor Boat & Yachting, Toby Heppell, How to guard against fire on board a boat — shout "fire"; get everybody to the muster point, Mayday, fight it with extinguishers; switch off the fuel supply; pull the engine room fire control; always have an exit behind you; plan how to get off if the fire envelops the boat; liferaft/tender launchable quickly | https://www.mby.com/training/how-to-guard-against-fire-on-board-a-boat-133399 | 2026-10-06 |
| S89 | NSW Government, What to do if there's a fire on a vessel — warn passengers and make a distress call; shut off fuel and gas lines; close all hatches, vents and ports to reduce oxygen; if abandoning, everyone in a lifejacket and leave from the windward side | https://www.nsw.gov.au/topics/waterways-safety-and-rules/emergencies/fire-on-board | 2026-10-06 |
| S90 | Yachting World, Will Bruton, How to stay afloat: top tips for rescuing a sinking yacht — work through every through-hull bow to stern; taste to check it is seawater; stern gland an Achilles heel; hoses double jubilee-clipped with tapered soft-wood plugs; electric and manual bilge pumps; a 5 cm hole 30 cm down lets in ~11,000 litres an hour, more than most manual pumps; Mayday only for imminent danger to life, Pan-Pan when serious but not grave/imminent | https://www.yachtingworld.com/features/stay-afloat-rescuing-sinking-yacht-124555 | 2026-10-06 |
| S91 | Yachting Monthly, Tom Cunliffe, Helicopter rescue at sea — the pilot briefs you on VHF; secure or stow loose gear (lifted by the downdraught); likely asked to motor upwind; if comms fail and it's breezy steer to weather or close-hauled on port tack; hi-line is a light weighted line on a weak link to the winch cable; flake it, don't secure it; earthing wire lowered into the water first; winchman is in charge | https://www.yachtingmonthly.com/sailing-skills/helicopter-rescue-at-sea-30559 | 2026-10-06 |
| S92 | Yachting Monthly, James Stevens, Why yachts make the best liferaft — if the yacht is afloat it is the best liferaft; abandon as a last resort; painter attached before launch; EPIRB distress before entering; take warm clothing and supplies; climb in without entering the water if possible, otherwise strongest first, waiting crew link arms over the raft's lifelines; cut the painter, stream the drogue, close the flap | https://www.yachtingmonthly.com/sailing-skills/why-yachts-make-the-best-liferaft-75184 | 2026-10-06 |
| S93 | RYA, SOLAS V regulations — skippers of pleasure craft must plan passages taking account of navigational hazards, weather forecasts, tidal predictions and other relevant factors including crew capability; the plan anticipates known hazards and adverse weather and ensures sufficient sea room; fit a radar reflector if possible, as high as possible | https://www.rya.org.uk/regulations/solas-v-regulations/ | 2026-10-06 |
| S94 | Penzance Sailing Club, Passage plans – Day Skipper & Yachtmaster — tidal heights for tidal entrances, tidal streams help/hinder/endanger, alternative destinations, forecasts on passage, wind against tide makes a rough sea, waypoints for GPS, a basic course to steer before setting off, pilotage plans, cross a TSS at right angles, mark off-lying dangers, lee shore = wind blowing onto the coast, fuel, distance ÷ speed for time | https://pzsc.org.uk/shorebased/passageplans/ | 2026-10-06 |
| S95 | Wikipedia, Watchkeeping — watches assign crew so the vessel is run continuously; traditional system of 4-hour watches with two 2-hour dog watches (1600–1800, 1800–2000) giving an odd number of watches so the rota rotates; two-section (port and starboard) and three-section systems | https://en.wikipedia.org/wiki/Watchkeeping | 2026-10-06 |
| S96 | MCA, MGN 632 (M+F) Amendment 2 — the Merchant Shipping (Prevention of Pollution by Garbage from Ships) Regulations 2020 apply to UK ships wherever they are; discharge of plastic into the sea prohibited since Annex V came into force over 30 years ago; food waste discharge only under specific regulations | https://www.gov.uk/government/publications/mgn-632-mf-amendment-2-the-merchant-shipping-prevention-of-pollution-by-garbage-from-ships-regulations-2020/mgn-632-mf-amendment-2-the-merchant-shipping-prevention-of-pollution-by-garbage-from-ships-regulations-2020 | 2026-10-06 |
| S97 | Yachting Monthly, How to avoid collisions in fog — navigation lights on; keep the mainsail up when motoring; engine running or ready; lifejackets on (also alerts the crew); liferaft ready; good radar reflector as high as possible; use radar if fitted; sound signals; lookout by sight and hearing (Rule 5); listening watch on VHF; plot positions | https://www.yachtingmonthly.com/sailing-skills/how-to-avoid-collisions-in-fog-71796 | 2026-10-06 |
| S98 | US Coast Guard Auxiliary District 7, Helicopter Operations Best Practices (PDF) — rotor blades generate static; let the basket or cable touch the boat before you touch it; never connect the cable to the boat; secure loose gear; sailboats furl and secure all sails | https://www.uscga-district-7.org/pdf/operations/helicopter_ops_best_practices.pdf | 2026-10-06 |
| S99 | RYA, Sailing grab bags — grab bag brightly coloured, floats for 30 min packed, stowed accessibly; EPIRB/PLB, flares, waterproof handheld VHF, torch, strobe, whistle, food and water, medication, seasickness tablets, documents | https://www.rya.org.uk/water-safety/safety-equipment/sailing-grab-bags/ | 2026-10-06 |
| S100 | Boattest, Mike Smith, How to extinguish an engine room fire — keep the engine hatch shut; opening it feeds the fire with air | https://boattest.com/view-news/4228_how-to-extinguish-an-engine-room-fire | 2026-10-06 |
| S101 | Wikipedia, Weather front — an occluded front is formed when a cold front overtakes a warm front | https://en.wikipedia.org/wiki/Weather_front | 2026-10-06 |
| S12 | Grog, Animated Knots — knot uses and tying sequence, used to check crossings | https://www.animatedknots.com/boating-knots | 2026-10-05 |
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Module 01 — The boat & nautical terms (live)
| Fact on the page | Source |
|---|---|
| Syllabus scope: parts of a boat and hull; general nautical terminology | S1 §1 |
| Bow, stern, port (left facing forward), starboard (right facing forward); fixed to the vessel | S4 (bow, stern, port, starboard) |
| Ahead, astern, abeam, on the bow, on the quarter, amidships, fore and aft, windward, leeward | S4 |
| Port sidelight red, starboard sidelight green | S7 (Rule 21, sidelights) |
| Keel, rudder, transom, cockpit, tiller, wheel, hull | S4 |
| LOA, beam, draught, freeboard, air draught (definitions) | S4 (length overall, beam, draft, freeboard, air draft) |
| Standing rigging (forestay, backstay, shrouds) vs running rigging; halyard hoists a sail, sheet trims it | S4 (standing rigging, running rigging, halyard, sheet) |
| Sail corners head/tack/clew and edges luff/leech/foot; jib vs genoa (overlaps the mast) | S4 |
| Catamaran: two hulls, bridgedeck, trampoline; same names for ends, sides, rig | S4 (catamaran), S5 |
| Example beams: Lagoon 42 7.70 m on 12.80 m LOA; Oceanis 40.1 4.18 m on 12.87 m; draughts 1.25 m vs 2.17 m | S5, S6 |
| Cat has two rudders and usually two engines | S5 (2 × 45 hp engines) |
| No heel on a cat; higher windage at low speed | General seamanship; see games/docking/rules.md for the handling model |
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Module 02 — Ropework & knots (live)
| Fact | Source |
|---|---|
| Syllabus scope: rope properties and construction; common knots, when to use them and how to tie them | S1 §2 |
| Laid rope: usually three strands, right-handed twist; braided rope; core-and-cover rope where the core takes most of the load | S17 (Styles: laid, braided, kernmantle) |
| Nylon: strong and elastic, absorbs water, 10–15% weaker wet. Polyester: ~90% of nylon's strength, stretches less, unaffected by water, better UV and abrasion resistance. Polypropylene: cheap, light, floats, limited UV/heat/friction resistance. HMPE (Dyneema/Spectra): high-performance fibre | S17 (Braided; Construction) |
| Uses on board (nylon for anchor/mooring lines, polyester for sheets/halyards, polypropylene for floating lines) follow from those properties | S17 + general seamanship |
| Bowline: fixed loop that won't slip or jam (mooring line over a post, sheet to a clew). Figure-of-eight: stopper in a sheet/halyard end. Clove hitch: quick temporary hitch (fenders to a guardrail). Round turn & two half hitches: secure under load, can be untied under load (mooring to a ring/post). Reef knot: two ends of the same line round something (reef points, sail ties). Sheet bend: joining two ropes, bight in the thicker one. Rolling hitch: grips a rope or spar against a lengthwise pull (clearing a riding turn). Cleating: holds firm, releases quickly | S12 (each knot's page); drawings drawn as Ashley's forms and checked crossing by crossing — reviews/knots-round-*.md |
| Catamaran: anchor bridle joined to the chain with a chain hook, soft shackle or rolling hitch | S14 |
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Module 03 — Safety equipment & lifejackets (live)
| Fact on the page | Source |
|---|---|
| Syllabus: safety equipment to be carried, its stowage and use; personal safety equipment, harnesses and lifejackets | S1 §4 |
| Lifejacket levels: 150 general coastal/offshore, turns an unconscious wearer on to their back; 275 offshore, extreme conditions or heavy clothing; 100 sheltered water, may not turn an unconscious person; 50 buoyancy aid for those who can help themselves | S18 |
| Gas inflation: manual; automatic water-activated (dissolving pellet/bobbin releases a spring); automatic pressure-activated (hydrostatic) fires only when fully submerged; automatics also have a manual toggle and an oral tube | S18 |
| Crotch straps stop the lifejacket riding up over your head; spray hood keeps spray and waves from the airways, cuts heat loss, adds visibility; a light makes you easier to find; whistle standard | S18 |
| Checks: fabric, webbing, buckles; toggle accessible; cylinder tight, uncorroded, at least its stamped minimum weight, correct charge (marked by the firing head); oral leak test; annual service by maker/agent; carry re-arm kits | S18, S19 |
| Jackstay: a line that lets crew move about without unclipping, independent on each side; clip on before coming on deck | S28 |
| Clip on to the windward jackstay with the shortest practical tether; never to guardrails | S24 |
| Liferaft: canister or valise; never stowed below; painter tied to a strongpoint; only step up into a liferaft | S25 |
| Pulling the painter to its end fires the gas cylinder; a hydrostatic release frees a cradle-stowed raft if the yacht sinks; weak link | S26 |
| Liferafts are not self-righting; serviced at set intervals by a certified station | S27 |
| Flares: red parachute rocket ~300 m, ~40 s, long range, not near a helicopter; red handheld ~1 min, a few miles, when help is in sight; orange smoke daylight only (~3 min buoyant); white flare = collision warning, not distress; hold handhelds downwind, outboard, tilted away; store cool, dry, accessible; out-of-date flares are less reliable | S20; distress signals S7 Annex IV |
| Fire classes A solids, B liquids, C gases, F cooking oil; bands water red (A), foam cream (A, B), powder blue (A, B, C, electrical), CO2 black (B, electrical), wet chemical yellow (A, F) | S21 |
| Fire needs oxygen (with fuel and heat); a fire blanket smothers it | Wikipedia, Fire blanket https://en.wikipedia.org/wiki/Fire_blanket |
| Pan fire: heat off if safe without leaning over, fire blanket, never water, no extinguisher, don't move the pan | S22 |
| Gas sinks to the lowest point; bottles upright in a locker draining overboard; off at the cylinder; alarm sensor where gas collects; leak drill (off, flames out, no switches, ventilate, competent check); never test with a flame | S23 |
| Catamaran callout: jackstays independent each side; escape hatch in each accommodation hull, above water when inverted, on the inner side; multihull liferaft deployable whether or not inverted | S28 |
| Kit stowage list (extinguishers by exits, flares near the companionway) and the fire-precautions callout are teaching guidance for the skipper's briefing, not quoted rules | — |
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Module 04 — Rules of the road (live)
All from S7 (MSN 1781, the COLREGs as applied in the UK), rule numbers given. Wording on the site is a plain-English paraphrase.
| Fact on the page | Source |
|---|---|
| Rule 5: keep a proper look-out at all times by sight, hearing and all available means | S7 Rule 5 |
| Rule 7: if in doubt, risk of collision exists; risk exists if the compass bearing of an approaching vessel does not appreciably change (may exist even with a change, e.g. a very large vessel or tow) | S7 Rule 7(a), (d) |
| Rule 8: action to avoid collision must be positive, in ample time, large enough to be readily apparent; course alteration alone may be most effective with sea room; result in passing at a safe distance | S7 Rule 8(a)–(d) |
| Rule 9: keep to the starboard side of a narrow channel; a vessel under 20 m or a sailing vessel shall not impede a vessel that can safely navigate only within it; do not cross if that impedes such a vessel; avoid anchoring in a narrow channel | S7 Rule 9(a), (b), (d), (g) |
| Rule 10: in a TSS proceed in the lane in the general direction of traffic; avoid crossing lanes, but if obliged cross on a heading as nearly as practicable at right angles to the traffic flow; vessels under 20 m, sailing vessels and fishing vessels may use the inshore traffic zone; if not using a TSS, avoid it by as wide a margin as practicable | S7 Rule 10(b), (c), (d), (h) |
| Rule 12: sailing vessels — wind on different sides: the one with the wind on the port side keeps clear; same side: the windward vessel keeps clear; port-tack vessel unsure of a windward vessel's tack keeps clear; windward side = the side opposite the mainsail | S7 Rule 12(a), (b) |
| Rule 13: any vessel overtaking keeps out of the way; overtaking = coming up from more than 22.5° abaft the other's beam (at night only her sternlight visible); if in doubt assume overtaking; stays the give-way vessel until finally past and clear | S7 Rule 13(a)–(d) |
| Rule 14: power-driven vessels meeting head-on each alter course to starboard and pass port to port | S7 Rule 14(a) |
| Rule 15: power-driven vessels crossing — the one with the other on her own starboard side keeps out of the way and avoids crossing ahead | S7 Rule 15 |
| Rule 16: give-way vessel takes early and substantial action to keep well clear | S7 Rule 16 |
| Rule 17: stand-on vessel keeps course and speed; may act once it is apparent the give-way vessel is not acting; must act when collision cannot be avoided by the give-way vessel alone; power-driven stand-on vessel in a crossing should not alter to port for a vessel on her own port side | S7 Rule 17(a)–(c) |
| Rule 18: power-driven underway keeps out of the way of NUC, RAM, fishing and sailing vessels; sailing keeps out of the way of NUC, RAM, fishing; fishing (so far as possible) of NUC and RAM; others avoid impeding a vessel constrained by her draught — except where Rules 9, 10 and 13 require otherwise | S7 Rule 18 |
| Rule 19: in restricted visibility, safe speed and engines ready; radar-only contact: avoid altering to port for a vessel forward of the beam (unless overtaking it) and avoid altering towards a vessel abeam or abaft the beam; hearing a fog signal forward of the beam: reduce to the minimum speed to hold course | S7 Rule 19(b), (d), (e) |
| Rule 3(d), (f), (g): engaged in fishing = nets, lines or trawls that restrict manoeuvrability, not trolling lines; not under command = unable to manoeuvre through some exceptional circumstance; restricted in ability to manoeuvre = by the nature of her work (e.g. dredging, cable laying, towing that restricts her course) | S7 Rule 3 |
| Rule 3: a sailing vessel under sail with its engine running is a power-driven vessel (definition: "sailing vessel" = under sail provided propelling machinery, if fitted, is not being used) | S7 Rule 3 |
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Module 05 — Lights, shapes & sound signals (live)
All from S7 (MSN 1781), rule numbers given; plain-English paraphrase on the site.
| Fact on the page | Source |
|---|---|
| Masthead light: white, 225°, right ahead to 22.5° abaft the beam each side. Sidelights: green starboard / red port, 112.5° each, right ahead to 22.5° abaft the beam. Sternlight: white, 135°, 67.5° each side of right aft. Towing light: yellow, as sternlight. All-round: 360° | S7 Rule 21(a)–(e) |
| Under 20 m the sidelights may be combined in one lantern; a sailing vessel under 20 m may combine sidelights and sternlight in one masthead lantern (tricolour), not to be used with the optional red-over-green all-round lights | S7 Rule 21(b), 25(b), 25(c) |
| Visibility, vessels under 12 m: masthead 2 M, sidelights 1 M, sternlight 2 M, all-round 2 M | S7 Rule 22(c) |
| Power-driven underway: masthead light forward, second higher masthead aft (optional under 50 m), sidelights, sternlight; under 12 m may show an all-round white plus sidelights | S7 Rule 23(a), (d) |
| Sailing underway: sidelights + sternlight; optional red over green all-round at the masthead; under sail and motor by day: cone apex down | S7 Rule 25(a), (c), (e) |
| Trawling: green over white all-round (+ masthead aft optional under 50 m); other fishing: red over white; both show sidelights + sternlight only when making way; day shape two cones apexes together | S7 Rule 26(b), (c) |
| NUC: two all-round red, two balls; RAM: red-white-red all-round, ball-diamond-ball; plus sidelights/sternlight (and masthead for RAM) when making way | S7 Rule 27(a), (b) |
| CBD: may show three all-round red in a vertical line, or a cylinder | S7 Rule 28 |
| Pilot on duty: white over red all-round at the masthead | S7 Rule 29(a) |
| At anchor: all-round white forward (ball by day) and a lower all-round white aft; under 50 m one all-round white may do; aground: anchor lights + two all-round red, three balls by day | S7 Rule 30(a), (b), (d) |
| Towing (tow ≤ 200 m): two masthead lights in a vertical line, sidelights, sternlight, yellow towing light above the sternlight; tow > 200 m: three masthead lights and a diamond shape | S7 Rule 24(a) |
| Manoeuvring signals (power-driven, in sight): 1 short = altering to starboard, 2 short = to port, 3 short = operating astern propulsion; at least 5 short and rapid = doubt about the other's intentions; 1 prolonged = nearing a bend | S7 Rule 34(a), (d), (e) |
| Fog signals at ≤ 2 min intervals: power making way 1 prolonged; power stopped 2 prolonged; sailing, fishing, NUC, RAM, CBD, towing 1 prolonged + 2 short; at anchor: bell rapidly ~5 s every minute; vessels under 12 m may instead make some other efficient sound signal at ≤ 2 min | S7 Rule 35(a)–(c), (g), (j) |
| Short blast about 1 s; prolonged blast 4–6 s | S7 Rule 32 |
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Module 06 — IALA A buoyage (live)
| Fact on the page | Source |
|---|---|
| One worldwide system in two regions differing only in lateral-mark colours | S2 (History; §2.2) |
| Region A: port marks red, starboard marks green; Region B reversed | S2 §2.4, §2.5 |
| Region B areas: the Americas, Japan, Republic of Korea, Philippines | S2 (History) |
| Conventional direction of buoyage: approaching a harbour, river, estuary or waterway from seaward, or as set by the authority, in principle clockwise round land masses; shown on charts | S2 §2.1 |
| Port mark: red can/pillar/spar, red can topmark, red light any rhythm except Fl(2+1). Starboard: green cone/pillar/spar, green cone topmark point up, green light | S2 §2.4.1–2.4.2 |
| Lateral marks numbered from seaward; even numbers on red, odd on green | S2 §2.3.3 |
| Preferred channel to starboard: red with one broad green band, can, red topmark, red Fl(2+1). To port: green with broad red band, cone, green topmark, green Fl(2+1) | S2 §2.4.3 |
| Cardinal quadrants; safe water on the named side; topmark cones point to the black | S2 §3, S3 |
| Cardinal colours: N black over yellow; S yellow over black; E black, yellow band, black; W yellow, black band, yellow | S2 §3, S3 |
| Cardinal lights white: N VQ/Q continuous; E VQ(3) 5s / Q(3) 10s; S VQ(6)+LFl 10s / Q(6)+LFl 15s; W VQ(9) 10s / Q(9) 15s | S3 (table), S2 §3 |
| VQ 120 or 100 flashes/min; Q 60 or 50; long flash ≥ 2 s; clock-face 3-6-9; long flash distinguishes S from W | S2 §3 |
| Isolated danger: on/near a danger with navigable water all round; black with red band(s); two black spheres; white Fl(2) | S2 §4 |
| Safe water: navigable water all round (fairway, mid-channel, landfall); red/white vertical stripes; single red sphere; white Iso, Oc, LFl 10s or Mo(A) | S2 §5 |
| Special marks: yellow, optional yellow X, yellow light with rhythms not used by white lights | S2 §6 |
| Emergency wreck marking buoy: blue/yellow vertical stripes in equal number, yellow upright cross, alternating blue/yellow light; marks new dangers | S2 (Marking new dangers) |
| Light abbreviations Fl, Q, VQ, LFl, Iso, Oc, Mo(A) | S2, S3 |
| Example light timings shown as "e.g." in the blinking demo (Fl(2) 5s, Fl(2+1) 10s, Fl R 5s, Fl Y 5s) are illustrations only, not rules | — |
| Catamaran callout: Lagoon 42 draught 1.25 m vs Oceanis 40.1 2.17 m | S5, S6 |
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Module 07 — Position, charts & publications (live)
| Fact on the page | Source |
|---|---|
| Syllabus: §6 latitude and longitude, standard navigational terms, true bearings and courses, the knot; §7 information on charts, chart symbols, direction and distance, publications, chart correction; §8 parallel rulers, dividers and proprietary plotters | S1 §6–8 |
| Latitude 0–90° N/S of the equator (parallels); longitude 0–180° E/W of the Greenwich prime meridian (meridians); 60 minutes to a degree | S30 |
| Nautical mile exactly 1,852 m, originally one minute of latitude; knot = 1 nautical mile per hour | S29 |
| Distance read on the latitude scale at the side, level with the line (Mercator scale increases away from the equator; longitude minutes shrink) | S31, S29 |
| A cable is one tenth of a nautical mile | Wikipedia, Cable length https://en.wikipedia.org/wiki/Cable_length |
| Bearings clockwise from north, 000–359°; true north reference; reciprocal = 180° apart | S40 |
| Plotter: ruler with a rotating protractor aligned with chart north (Portland/Breton type) | S37 |
| Depths below chart datum in metres (decimetres as the small figure); chart datum usually LAT; heights on land and of lights above MHWS; depth contours show the seabed shape | S32, S33, S34 |
| Underlined figures are drying heights above chart datum; seabed abbreviations S, M, Sh, R; Wk; dotted danger line; light characteristic Fl(3) 15s 21m 12M read as flashes, period, height, range | S34 |
| Almanac contents (tide tables and streams, harbour plans, lights and buoyage, waypoints, distance tables, radio, weather, safety) | S38 |
| Pilot books / sailing directions contents | S39 |
| Notices to Mariners: weekly from the UKHO; leisure NMs free on the ADMIRALTY website | S35, S36 |
| Chart correction steps: fine magenta pen, Chart 5011; decide relevance; insert new before deleting, two diagonal lines through the old; colour blocks cut (black line trimmed) and glued; NM number and year bottom left, also for NMs judged not applicable | S35 |
Kerran Sound lat/long grid (49°48'·0N 007°30'·0W at the top-left, 70 units per minute of latitude, 45 per minute of longitude) and the WP1→WP2 example (131°T, 8.7 M) are fictional, computed by site/assets/js/chart.js | — |
| Catamaran callout: Lagoon 42 draught 1.25 m vs Oceanis 40.1 2.17 m — work from your own boat's draught | S5, S6 |
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Module 08 — The compass: variation & deviation (live)
| Fact on the page | Source |
|---|---|
| Syllabus: §9 application of variation, deviation and its causes, use of hand-bearing compass | S1 §9 |
| Variation: angle between true and magnetic north, East or West, changes with place and slowly over years | S41 |
| Chart rose gives variation, year and annual change; update = years × annual change (worked: 3°40'W 2016 (9'E) → 2°10'W in 2026, quiz 4°15'W 2016 (8'E) → 2°55'W) | S41, S45 |
| Deviation caused by iron/steel (engine, anchor, tools) and electrical equipment (wiring, plotters, anything magnetic); varies with heading | S42, S43, S45 |
| Swinging the compass on several headings; corrector magnets; residual deviation on a card | S42 |
| Conversion order TVMDC, "True Virgins Make Dull Company"; true → compass add West subtract East ("error West compass best"); compass → true CADET, add East | S45, S46 |
| Hand-bearing compass: sighting prism, bearings of landmarks; used away from metal no deviation, apply variation only | S44, S45, S43 |
| Steady bearing of an approaching vessel means risk of collision | S7 Rule 7 |
| Lubber line marks the heading on the steering compass | S43 |
| Kerran Sound variation and Kittiwake's deviation card (000 1°E, 045 3°E, 090 4°E, 135 2°E, 180 1°W, 225 3°W, 270 4°W, 315 2°W) are fictional; WP1→WP2 131°T from Module 07 | — |
| Catamaran callout: steering compass at the bridgedeck helm station near engine controls and electronics — check deviation there, under way with electronics on (follows from S42/S43 causes) | S42, S43 |
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Module 09 — Tides: heights & the rule of twelfths (live)
| Fact on the page | Source |
|---|---|
| Syllabus: §11 tidal definitions, levels and datum; tide tables; Admiralty method for tidal height at a standard port | S1 §11 |
| Most coasts: two high and two low waters a day, about 12 h 25 min apart | S50 |
| Springs around new and full moon (sun, moon, Earth in line), big range, higher HW and lower LW, stronger streams; neaps at the quarter moons (90° apart), small range; about 7 days apart; springs lag 1–2 days (36–48 h) after full/new moon | S49, S50 |
| Chart datum: the level charted depths, drying heights and tide heights are measured from; UK charts use LAT, the lowest tide predictable under average weather, so predicted heights are almost never negative | S48, S47 |
| MHWS, MLWS, MHWN, MLWN: mean high/low water springs/neaps | S47, S48 |
| Height of tide: water level above chart datum at a given time (what the tide table gives); range = HW height − LW height | S47, S48, S50 |
| Charted depth (sounding): below datum; drying height: above datum, underlined on the chart; depth = charted depth + height of tide; over a drying patch, depth = height of tide − drying height | S47, S48 |
| Tide tables give daily times and heights of HW and LW at standard ports | S47 |
| Tidal curve method at a standard port: work out the range, draw the line from LW height to HW height, write in the times from HW, go from the time up to the curve, across to the line, read the height | S47 |
| Rule of twelfths: 1, 2, 3, 3, 2, 1 twelfths of the range in the six hours; assumes a regular ~6 h, sine-shaped rise; rough approximation only; not for places with double HW/LW (Solent, Poole, Weymouth Bay) | S51 |
| Clearance under the keel = depth − draught; keep at least 1 m, more in waves or swell | S47 |
| Port Kerran tide day (LW 0600 0.6 m, HW 1200 4.8 m, LW 1825 0.9 m), levels (MHWS 5.0, MHWN 3.9, MLWN 1.8, MLWS 0.5 m), Port Kerran curve, harbour bar charted 1.2 m and Kerran Spit drying 0.8 m are fictional, for practice | — |
| Catamaran callout: Lagoon 42 draught 1.25 m vs Oceanis 40.1 2.17 m — over the 1.2 m bar with a 1 m margin the cat needs 1.05 m of tide (from about 0800 by twelfths), the monohull 1.97 m (from about 0900): same method, different answer | S5, S6, S47 |
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Module 10 — Tides: secondary ports (live)
| Fact on the page | Source |
|---|---|
| Syllabus: corrections for secondary ports | S1 §11 |
| Standard ports have daily HW/LW times and heights and their own tidal curve; secondary ports are given time and height differences from a standard port | S47, S52 |
| Time differences are given for particular standard-port HW and LW times; height differences for MHWS, MHWN, MLWN, MLWS (springs and neaps) | S52 |
| Interpolation: when the standard port's time or height falls between the table's figures, take the same fraction of the change in the difference and add it to the first difference | S52 |
| Heights between HW and LW at a secondary port: use the standard port's tidal curve with the secondary port's HW time and HW/LW heights | S52, S47 |
| Clearance = depth − draught; keep at least 1 m; depth = charted depth + height of tide | S47 |
| Carrick Haven (differences HW +0040 at 0000/1200, +0020 at 0600/1800; LW +0030 at 0500/1700, +0010 at 1100/2300; MHWS −0.8, MHWN −0.3, MLWN −0.2, MLWS −0.1; entrance charted 0.8 m) and the worked answers (HW 1240 4.1 m, LW 0627 0.5 m, 0940 2.3 m) are fictional, for practice; the curve shape at HW−3 (half the range) is the course's Port Kerran curve | — |
| Catamaran callout: Lagoon 42 draught 1.25 m vs Oceanis 40.1 2.17 m — same working, only the clearance changes: at 0940 1.85 m vs 0.93 m; tide needed with a 1 m margin over 0.8 m: 1.45 m vs 2.37 m | S5, S6, S47 |
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Module 11 — Tidal streams (live)
| Fact on the page | Source |
|---|---|
| Syllabus: tidal diamonds and tidal stream atlases for chartwork | S1 §11 |
| Tidal diamond: magenta letter in a rhombus; its table gives, for each hour from HW−6 to HW+6 at a standard port, the direction (degrees true, the way the stream flows towards) and the spring and neap rates in knots | S53, S54 |
| Each row covers the tidal hour from half an hour before to half an hour after its time | S54 |
| Tidal stream atlas: 12–13 chartlets, one per hour; arrow direction, thicker = stronger; rate pairs in tenths of a knot, neaps then springs (37,52 = 3.7 / 5.2 kn) | S53 |
| Streams are stronger at springs than at neaps | S53, S50 |
| Rates between neaps and springs are interpolated (calculation-of-rates / interpolation chart); the page does it as a straight-line share of the way from the neap to the spring figure using the day's range against the mean neap and spring ranges — the same linear interpolation as Module 10 | S53, S54, S52 |
| Set = direction of the stream; drift = its rate; in one hour a stream of n knots carries the boat n miles in its set | S53 |
| Kerran Point diamond A (HW−3 at Port Kerran: 065°, springs 2.6 kn, neaps 1.0 kn) and the worked answers (day's range 4.2 m vs mean springs 4.5 m and neaps 2.1 m from the Port Kerran levels, ≈ 0.9 of the way to springs, rate ≈ 2.4 kn, HW−3 row 0830–0930) are fictional, for practice | — |
| Catamaran note: the stream moves the water and so carries any boat in it equally; the working is identical for a catamaran | S53 (set and drift apply to the boat, whatever its hull) |
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Module 12 — Chartwork: DR, EP, fixes & course to steer (live)
| Fact on the page | Source |
|---|---|
| Syllabus: dead reckoning and estimated position, awareness of leeway; visual fixing; satellite-derived positions; use of waypoints to fix position; course to steer | S1 §10 |
| Dead reckoning (DR): from the last known position, plot the course steered and the distance run through the water (log) | S55 |
| Leeway: the wind pushes a sailing boat sideways, to leeward; the water track is turned away from the wind by the leeway angle | S55 |
| Estimated position (EP): DR plus leeway and the tidal stream's set and drift for the time; marked with a triangle; the line from start to EP is the ground track / course made good | S53, S55 |
| Fix > EP > DR in reliability | S55 |
| Three-point visual fix: bearings of three charted objects, spread about 120° (90° for two); the lines form a cocked hat; small is good; near a danger assume the corner closest to it | S55, S56 |
| Satellite (GPS) positions: computed from many satellites; plot the position and confirm it with an independent check (bearing, depth) | S56, S1 §14 |
| Waypoint: a chosen point (a route is an ordered list of them); bearing and range to a waypoint fix you on the reciprocal bearing from it at that distance | S55, S40 |
| Course to steer: draw the ground track to the destination; from the start lay off one hour of tidal stream; from its end swing an arc of boat speed (one hour's distance) to cut the track; that line is the water track; start to the cut is the speed over the ground; then allow leeway into the wind, variation, deviation last | S53, S55 |
| Worked figures (fictional): 0830 fix, heading 000°T, log 5.0 M, leeway 5° with a westerly wind → water track 005°T, stream 065° 2.4 kn (Module 11) → EP 0930 about 6.5 M on 024°T; three-point fix bearings 020°, 140°, 290°; KS1 bearing 040° 2.0 M → 2.0 M on 220° from KS1; CTS to KS2 6 M on 000°T: water track 334°T, SOG ≈ 5.5 kn, steer 329°T | — (geometry checked: 5 sin 5° + 2.4 sin 65° = 2.61, 5 cos 5° + 2.4 cos 65° = 6.00; asin(2.175 ÷ 5) = 25.8°, 5 cos 25.8° + 1.01 = 5.52) |
| Catamaran: leeway is a property of the boat and can differ from a monohull's; on a daggerboard cat it grows when the boards are raised (they resist the leeward push); the construction is the same | S55, S57 |
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Module 13 — Pilotage & harbour entry (live)
| Fact on the page | Source |
|---|---|
| Syllabus: transits, leading lines and clearing lines; use of sailing directions; pilotage plans and harbour entry; lighthouses and beacons | S1 §16, §12 |
| Pilotage: navigating by eye close to land, from visible fixed marks, planned on the chart in advance | S58, S55 |
| Transit: two charted objects in line; you are somewhere on the line through them; needs no compass, so it also checks the compass | S58, S55 |
| Leading line: a pair of leading marks (lit: leading lights), front lower than rear; in line = on the safe track into the channel; for a turn, line up the next pair | S58, S59, S55 |
| Clearing (danger) bearing: drawn in advance from a charted object past the danger; labelled NMT (not more than) or NLT (not less than) depending on which side is safe; check it with the hand-bearing compass; a transit can be a clearing line too; a turn bearing is planned the same way | S55 |
| Sectored light: white sector = safe channel; red = port edge, green = starboard edge, approaching the light; sector bearings are true, from seaward; colour changes, characteristic does not | S60 |
| Light characteristic identifies a lighthouse: Fl(3) 15s 21m 12M = three flashes every 15 s, 21 m high, 12 M range | S62 |
| Sailing directions (pilot books): hazards, buoyage, pilotage, regulations, anchorages, port facilities, photos — the local knowledge a pilot would give; read them before the pilotage plan | S61, S58 |
| Harbour entry: keep to the starboard side of a narrow channel; do not impede vessels confined to it (Rule 9); watch the depth on the sounder | S7 Rule 9, S58 |
| Worked plan (fictional): Port Kerran leading marks in line 352°T; Gull Island light NLT 030°T clears The Mewstone; Port Kerran pierhead Iso WRG 4s: W 349°–355°, R 355°–010°, G 335°–349°; Gull Island light Fl(3) 15s 21m 12M (course chart) | — (geometry: observer east of a clearing line through a light to the NE sees the light at a smaller bearing, so danger to the east → NLT; on 352° approach, red (bearing > 355°) = boat west = port side) |
| Catamaran: much wider beam (Lagoon 42 7.70 m vs Oceanis 40.1 4.18 m) matters in narrow entrances and marinas; shallower draught (1.25 m vs 2.17 m) does not replace the pilotage plan | S5, S6 |
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Module 14 — Meteorology & forecasts (live)
| Fact on the page | Source |
|---|---|
| Syllabus: sources of broadcast meteorological information; shipping forecast terms, Beaufort scale, significance to small craft; highs, lows, fronts; sea and land breezes; fog | S1 §13 |
| Shipping forecast: by the Met Office, read on BBC Radio 4 on behalf of the MCA; 31 sea areas read clockwise round Britain (names as listed on the page); order gale warnings → general synopsis → each area's wind, weather, visibility | S63 |
| Inshore waters forecast: up to 12 miles offshore, 19 areas; issued 0000/0600/1200/1800 UTC, valid 24 h; wind, weather, visibility, sea state | S64 |
| Navtex: 518 kHz and 490 kHz, about 270 M; gale warnings, forecasts and outlooks, navigation warnings | S65 |
| HM Coastguard MSI on VHF: announced on Ch 16, read on Ch 62, 63 or 64; VHF range about 30 miles; inshore forecast and gale/strong wind warnings every three hours; strong wind warning = force 6+ forecast in an inshore area | S65 |
| Imminent < 6 h, soon 6–12 h, later > 12 h, from the time of issue | S9 |
| Gale force 8 (34–40 kn) or gusts 43–51 kn; severe gale force 9 (41–47 kn) or gusts 52–60 kn; storm force 10 (48–55 kn); violent storm force 11 (56–63 kn) | S9 |
| Visibility: good > 5 M, moderate 2–5 M, poor 1,000 m–2 M, very poor < 1,000 m | S9 |
| Sea state: smooth < 0.5 m, slight 0.5–1.25, moderate 1.25–2.5, rough 2.5–4, very rough 4–6, high 6–9, very high 9–14, phenomenal > 14 m | S9 |
| Veering = clockwise shift (SW to W); backing = anticlockwise (SE to NE); system speeds slowly < 15 kn, steadily 15–25, rather quickly 25–35, rapidly 35–45 | S9 |
| Beaufort table: force names, sea-state terms and probable wave heights (0.1, 0.2, 0.6, 1, 2, 3, 4, 5.5, 7, 9, 11.5, 14+ m); values are for well-developed open-sea waves, with a lag behind the wind | S8 |
| Beaufort knot ranges 0–12 and short sea descriptions | S67 |
| Isobars; wind almost parallel to them; closer = stronger; highs: sinking air, little cloud, fine, light winds, clockwise (NH); lows: rising air, cloud and rain, unsettled, anticlockwise (NH) | S68 |
| Buys Ballot: back to the wind in the NH, low pressure on the left | S68 |
| Diagram: depression with warm front (semicircles) and cold front (triangles), warm sector, anticlockwise wind; chart convention warm = red semicircles, cold = blue triangles | S68 (the page draws the warm front in chart magenta, cold front in sea blue, per the site palette) |
| Warm front: cirrus → cirrostratus → altostratus → nimbostratus; pressure falls, wind backs; rain about 6–8 h after high cloud spreads with falling pressure; poor visibility; persistent rain then drizzle; wind veers (SE→SW); warmer | S69 |
| Cold front: narrow band of rain, sometimes heavy, cumulonimbus/thunder; wind veers (SW→NW); temperature drops; pressure rises sharply; clears behind, visibility good except in showers; moves faster, sharper changes | S70, S68 |
| Occluded front: forms when a cold front catches up with (overtakes) the warm front | S101 |
| Sea breeze: land heats faster, air rises, onshore surface wind in the afternoon, sets in after sunrise, return flow aloft, cumulus line over land, 10–100 km from coast; land breeze at night, land cools faster, shallower/weaker | S71 |
| Fog = visibility < 1,000 m; radiation fog: clear calm nights, over land, mostly winter, clears soon after sunrise; sea/advection fog: warm moist air over a colder sea, carried in over the coast on the wind, UK east coast spring and summer | S72 (“a breeze does not clear it” is derived from advection = air moved by the wind) |
| Catamaran: does not heel to warn it is overpowered; reef early; reef by the instruments' true wind using the boat's own reefing table | S66 (no maker/charter reefing numbers found, so no table on the page) |
| Strong wind warning as the cue to reef before leaving | Teaching advice built on S65 (force 6+ definition) |
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Module 15 — Passage planning, watchkeeping & fog (live)
| Fact on the page | Source |
|---|---|
| Syllabus: passage planning (SOLAS V); navigation in restricted visibility; passage making, watchkeeping, the marine environment | S1 §14, §15, §17 |
| SOLAS V applies to pleasure craft: plan before going to sea, taking account of hazards, forecast, tidal predictions, boat and crew capability; enough sea room; detail depends on boat, crew and trip | S93 |
| Plan contents: charts and pilot books, off-lying dangers marked, lee shore, forecast before and during passage, tidal heights for entrances, tidal streams, wind against tide = rough sea, tidal gates, distance ÷ speed = time, waypoints for GPS, a basic course to steer, pilotage plans, alternative ports (bolt holes), fuel | S94 |
| Cross a traffic separation scheme on a heading as nearly as practicable at right angles to the traffic flow | S7 Rule 10, S94 |
| Check GPS independently: bearing fix (small cocked hat gives confidence), transit, depth contour | S56, S58 |
| Rule 5: proper look-out at all times by sight, hearing and all available means | S7 Rule 5 |
| Watches: 4-hour watches; dog watches 1600–1800 and 1800–2000 make seven a day so the rota rotates; two- (port and starboard) and three-section systems (three sections give longer sleep) | S95 |
| Rule 19: safe speed and engine ready in restricted visibility; radar-only rules; hearing a fog signal forward of the beam → minimum speed to keep course | S7 Rule 19 |
| Fog precautions: fix and plot position; lifejackets on (and alerts the crew); liferaft ready; lookout by sight and hearing; radar if fitted; VHF listening watch; navigation lights on; radar reflector as high as possible; mainsail up when motoring; engine running or ready; sound signals | S97, S93 |
| Fog signals ≤ 2 min: sailing 1 prolonged + 2 short; power making way 1 prolonged; stopped 2 prolonged; < 12 m may make another efficient sound signal; prolonged 4–6 s, short ~1 s | S7 Rules 32, 35 |
| Plastic discharge banned for 30+ years under MARPOL Annex V; applies to UK ships of every size wherever they are; food waste only under specific conditions | S96 |
| Catamaran: Lagoon 42 draught 1.25 m vs Oceanis 40.1 2.17 m; beam 7.70 m vs 4.18 m | S5, S6 |
| Worked plan (fictional): 15 M at 5 kn = 3 h; Gull Island channel gate 10 M out, stream up to 3 kn at springs, slack 1300, pass within an hour of slack, leave 1100 (10 M at 5 kn = 2 h); bolt holes Port Kerran (before the gate) and the Gull Island east-side anchorage (after it); WP2 keeps a wide berth off The Mewstone | — (practice figures, arithmetic) |
| Engine driving the boat = power-driven vessel even with sails up; long-short-short is also the fog signal for vessels fishing, towing, NUC and RAM | S7 Rules 3, 35 |
| Quiz: 10 M at 5 kn = 2 h → leave 1100 for a 1300 gate | — (arithmetic) |
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Module 16 — Anchoring & mooring (live)
| Fact on the page | Source |
|---|---|
| Syllabus: characteristics of different anchors; considerations when anchoring | S1 §3 |
| Plough (CQR, 1933 hinged design): good in most seabeds, exceptional in none; Delta: rigid-shank plough, self-launching from a bow roller, holds reasonably in hard bottoms; Danforth/fluke: light, buries and holds well in sand and mud, poor in weed and gravel, can skate if dropped while moving; Bruce/claw: sets first time in many bottoms, turns rather than breaking out, weak in weed, low holding for its weight; scoop/roll-bar types (e.g. Rocna, Spade): set very well, can be hard to weigh | S13 |
| Scope: all chain ≈ 4 × depth; chain and rope ≈ 6 × depth | S10 |
| Choose an anchorage with good holding (sand, mud), enough depth and shelter from wind and waves; check the chart for foul ground, cables and "anchoring prohibited" | S15 |
| Lay the anchor by motoring slowly head to wind or stream, lowering it to the seabed, paying out cable as the boat falls back, then setting it with gentle reverse | S15 |
| Anchor watch: check position with transits/bearings or a GPS anchor alarm | S15 |
| At anchor show a black ball by day, an all-round white light at night | S7 Rule 30 |
| Swinging circle: the boat can lie anywhere on a circle around the anchor whose radius is roughly the cable let out plus the boat's length (geometry of the scope; teaching approximation) | derived from S10 scope + boat length |
| Mooring lines: bow (head) line, stern line, springs (stop the boat surging fore and aft), breast lines (hold her in) | S16 |
| Catamaran bridle: a line from each bow to the chain reduces sheering and takes the load off the windlass | S14 |
| Quiz distractor: two balls / red over red = not under command, not anchored | S7 Rule 27(a) |
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Module 17 — VHF radio & distress calls (live)
| Fact on the page | Source |
|---|---|
| Syllabus: RYA §4 Safety, distress calls | S1 §4 |
| VHF travels by line of sight; obstructions block it; range depends on aerial height | S76, S75 |
| About 5 miles between small boats with low aerials; up to about 60 miles between a hill aerial and a tall mast | S75 |
| Radio horizon ≈ 4.12 × √h km: 1.5 m → ≈ 2.7 M, 16 m → ≈ 9 M, 100 m → ≈ 22 M; two stations add their horizons (9 + 22 ≈ 31 M) | S76 (formula), S29 (1 M = 1,852 m) — arithmetic: 4.12×1.225=5.05 km, 4.12×4=16.5 km, 4.12×10=41.2 km |
| Fixed set: more reliable power, higher power, bigger/better aerial, larger display and buttons; handheld lower aerial, shorter range | S75 |
| Power limited to 25 W; high/low switch 25 W / 1 W; some channels (e.g. 13) low power only, set won't select high | S75, S82 |
| Single frequency (simplex): PTT turns transmitter on and receiver off, so you can't hear while transmitting | S75 |
| Over = finished, expecting reply; Out = end of conversation | S75 |
| Identify yourself every time you transmit | S82 |
| Ch 16: distress, safety and calling, monitored around the clock by coastguards; make contact then switch to a working channel to keep 16 clear | S75, S73 |
| Ch 70: DSC only; DSC sets listen to it continuously | S75, S77 |
| Ch 13: bridge-to-bridge navigation safety, 1 W, larger ships (>20 m) keep watch | S75, S73 |
| Ch 6: intership | S75 |
| Ch 67: UK small-ship safety channel | S75 |
| Harbours publish working channels in the almanac and pilot book | S38, S61 |
| Dual watch: listen to a chosen channel while checking 16; tri-watch adds a third | S82; watch on 16 when not on another channel: S75 |
| DSC: digital calls on ch 70; individual calls or all-station alerts | S77, S73 |
| MMSI: 9 digits, identifies the boat; first three digits = country; issued with the Ship Radio Licence and stays with the vessel for life | S78, S74, S81 |
| GPS connected → alert carries position along with MMSI and time | S77, S74 |
| Red distress button under a protective, often spring-loaded cover; press and hold until the alert is sent | S77, S73, S74 |
| Set repeats the alert if unacknowledged | S77 |
| Red button raises the alarm; Mayday voice call and message on 16 follow | S74, S73 |
| Mayday only for grave and imminent danger to a vessel or person with immediate help required (fire, sinking, man overboard) | S73, S74 |
| Mayday from French m'aider; false distress call a criminal offence in many countries | S79 |
| Procedure: DSC alert → wait for acknowledgement or ~15 s → ch 16 high power → call and message → Over → listen on 16 | S73, S74 |
| Message order (MIPDANIO aid): Mayday ×3, This is, name ×3, call sign, MMSI; Mayday, name, call sign, MMSI, position (lat/long preferred), nature of distress, assistance required, persons on board, other information, Over | S73 (MIPDANIO is a mnemonic of that order, named in the brief) |
| Keep a Mayday card by the radio | S74 |
| Mayday card for Kittiwake off Kerran Sound, 2 miles S of Gull Island light, 4 aboard | — (fictional worked example; Gull Island from the course chart) |
| Pan-Pan: urgent, no immediate danger to life or vessel; from panne; examples engine failure clear of danger, medical advice, uncertain position with no stranding risk | S79 |
| Pan-Pan: no red button; DSC urgency call, then voice on 16; Pan pan ×3, All stations ×3, This is name ×3, call sign, MMSI; working channel may be nominated | S74, S73 |
| Sécurité: said three times; navigation and weather warnings (e.g. hazard adrift, gale); call on 16, message on a working channel | S79 |
| Mayday > Pan-Pan > Sécurité | S79 |
| Must cancel a false alert: follow the screen or off/on after 10 s, self-cancel if possible, ch 16, "All stations" ×3, This is name ×3, call sign, MMSI, "please cancel my distress alert of" + time UTC | S80, S77 |
| Ship Radio Licence from Ofcom needed before using the set; online portal; lifetime of the vessel; includes MMSI and call sign; not transferable; no licence = criminal offence; separate ship portable licence | S81, S75 |
| SRC: minimum legal qualification to operate VHF/DSC on a British-flagged vessel; ~2-day course and exam | S74, S75 |
| Catamaran: procedure identical; range depends on aerial height, not hull type | S76 (no multihull-specific VHF difference found in the sources) |
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Module 18 — Emergencies: MOB, fire & rescue (live)
| Fact on the page | Source |
|---|---|
| Syllabus: emergencies sit in §4 Safety | S1 §4 |
| MOB first actions: shout (repeated by the crew); one spotter watches and keeps pointing, calling direction and distance; throw lifebuoy and danbuoy at once; press MOB on plotter/GPS (records the position); Mayday on VHF | S83, S84 |
| Cold water shock below ~15 °C: gasp and uncontrolled breathing, can inhale water; first couple of minutes; hypothermia after ~30 min | S86 |
| Quick stop: tack without touching headsail sheets → hove to near the casualty; if too far, sheet main, keep turning, gybe, back downwind, round up | S84 (S83 for the gybing RORC variant) |
| Reach-tack-reach: beam reach away a few lengths, tack, come back on a close reach, sheet in to speed up / let flap to stop; RYA stops with casualty on the leeward side | S83, S84 |
| Under power: check no lines trailing near the stern before putting the engine in gear | S83, S84 |
| Engine in neutral / stopped near the casualty | S87 (stated for catamarans; taught here as the general rule — teaching guidance) |
| Getting aboard: stern ladder quick but dangerous in a big sea; bowline to a winch; rescue sling + handy billy on main halyard, halyard alone hard work; parbuckle with a sail, hard on a windy day | S85 |
| Lift horizontally after long immersion (loss of hydrostatic pressure support); collapse before/during/after rescue; after short immersion speed matters more | S84, S85, S86 |
| "Deck is closer to the water on the leeward side" (reason for leeward pick-up) | Teaching gloss on S83's leeward pick-up — no source states the freeboard reason verbatim |
| Catamaran callout: no heel, high topsides; transom steps / sugar scoop; boathook; propellers further outboard and nearer the surface, engines off or neutral; blind spots, side-deck spotter; dinghy on davits to help | S87 |
| Fire drill: shout "Fire"; crew to the muster point; Mayday; fuel off (and gas off); fight with an exit behind you; close hatches, vents and ports to cut oxygen | S88, S89 |
| Engine-room fire: fuel off, pull the engine-room fire control (fixed extinguisher) | S88 |
| Keep the engine hatch shut: opening it lets in fresh air and can make it worse | S89 (close hatches to reduce oxygen); S100 |
| When to stop fighting: plan the exit, liferaft/tender ready; leave from the windward side in lifejackets | S88, S89 |
| Flooding: taste for seawater; every through-hull bow to stern; seacocks; stern gland weak point; hoses double-clipped; tapered softwood bungs; electric + manual pumps; 5 cm hole 30 cm down ≈ 11,000 L/h, more than most hand pumps; Mayday = imminent danger to life, Pan-Pan = serious, not imminent | S90 |
| A tapered softwood bung beside each seacock | S90 |
| Helicopter: VHF briefing; secure loose gear (downdraught); furl sails; motor steadily upwind as told, or to weather / close-hauled on port tack if comms fail | S91; S98 (furl sails) |
| Static: don't touch the wire/hook/stretcher until it has touched the sea or the boat | S98; S91 (earthing wire lowered into the water first) |
| Hi-line: light weighted line on a weak link; take in only when told; second crew coils the slack; never tie it or the wire to the boat; weak link breaks if it snags | S91; S98 (never connect the cable; haul as directed) |
| No parachute rockets near a helicopter; use handheld red or orange smoke | S20 |
| Liferaft decision: a floating yacht is the best liferaft; only step up | S92, S25 |
| Abandoning: lifejackets; Mayday and EPIRB/PLB before leaving; painter to a strong point; grab bag, warm clothing, supplies; board dry if possible, else strongest first and others link arms over the raft lifelines; cut painter when all in, stream drogue, close flap | S92, S25, S26; RYA grab bags (PLB) |
| Grab bag: bright, floating, easy to reach; EPIRB/PLB, waterproof handheld VHF, flares, torch, strobe, whistle, water and food, seasickness tablets, medication, documents | S99 |
| Diagrams: reach-tack-reach plan view; helicopter wire-earth / hi-line / winchman sequence | Drawn from S83, S84, S91 and S98 |
| "Practise MOB with a fender and bucket each season" sidenote | Teaching guidance, not a quoted rule |
Module key facts and sources
| Module | Fact | Source |
|---|---|---|
| 04 | Steering & sailing rules examined: 5, 7, 8, 9, 10, 12–19 | S1 §5, S7 |
| 04 | Rule 12 (sailing vessels): port tack gives way to starboard tack; same tack, windward gives way to leeward | S7 Rule 12 |
| 04 | Rule 13: any overtaking vessel keeps out of the way; Rule 14: power-driven vessels head-on both alter to starboard; Rule 15: crossing — the one with the other on her starboard side gives way | S7 |
| 05 | Masthead light 225°, sidelights 112.5° each, sternlight 135° | S7 Rule 21 |
| 09 | Rule of twelfths: 1/12, 2/12, 3/12, 3/12, 2/12, 1/12 of the range in each of the six hours (assumes a regular ~6-hour rise) | To source in the module item (UKHO / RYA Navigation Handbook equivalents); approximation only |
| 14 | Beaufort scale 0–12; force 8 gale 34–40 kn; force 9 severe gale 41–47 kn; imminent < 6 h, soon 6–12 h, later > 12 h | S8, S9 |
| 16 | Scope: 4 × depth for all chain, 6 × depth for rope and chain; swinging circle radius ≈ scope (plus boat length) | S10 (and the brief) |
| 17 | Distress on VHF Ch 16 (and DSC Ch 70); Mayday / Pan-Pan / Sécurité | To source in the module item (MCA / HM Coastguard guidance) |