What COLREGS are

The International Regulations for Preventing Collisions at Sea (COLREGS) are the rules of the road afloat. Every powerboat driver must know them cold - they decide who gives way, who holds course, and how vessels signal intentions in poor visibility.

Look-out and safe speed

Every vessel must keep a proper look-out by sight, hearing and all available means at all times (Rule 5). Speed must be safe for conditions - visibility, traffic density, sea state, and your boat's stopping distance and turning ability all count (Rule 6). There is no single numeric speed limit in COLREGS itself; safe speed is judged against these factors.

Risk of collision and action to avoid it

If in doubt, assume risk of collision exists (Rule 7). Any action taken to avoid collision should be positive, made in good time, and large enough to be obvious to the other vessel (Rule 8). Small, late nudges are a classic exam trap - the rule wants early, bold, obvious action.

The give-way hierarchy (Rules 12-18)

• Sail overtakes power: a vessel under sail alone normally has right of way over a powered vessel, EXCEPT when overtaking (Rule 13) - the overtaking vessel always keeps clear, sail or power.
• Head-on (Rule 14): both power-driven vessels alter course to starboard so they pass port-to-port.
• Crossing (Rule 15): the vessel which has the other on her own starboard side gives way and should avoid crossing ahead.
• Give-way vessel (Rule 16): must take early and substantial action to keep clear.
• Stand-on vessel (Rule 17): keeps course and speed, but must act to avoid collision if the give-way vessel fails to.
• Pecking order when not overtaking: power gives way to sail, sail gives way to fishing vessels engaged in fishing, and everyone gives way to vessels restricted in ability to manoeuvre or not under command (Rule 18).

Narrow channels and traffic separation

In a narrow channel keep as far to the starboard side as is safe and practicable (Rule 9); small craft under 20m and sailing vessels must not impede vessels that can only navigate safely within the channel. In Traffic Separation Schemes, join and leave at the shallowest angle and avoid crossing lanes unnecessarily (Rule 10).

Lights, shapes, sound signals

Learn the standard navigation light configurations (masthead, sidelights, sternlight) and shapes shown by vessels restricted in manoeuvring, fishing, or towing. In restricted visibility, sound signals (one prolonged blast every two minutes underway) substitute for sight. Short blasts signal intention: one short blast = altering to starboard, two = altering to port, three = operating astern propulsion, five or more short rapid blasts = danger/doubt (Rule 34).

Common mistakes

Candidates often mix up who is the give-way vessel in crossing situations, forget the overtaking exception to sail-over-power, or think COLREGS gives a fixed speed limit instead of a judgement call. Always check: is this head-on, crossing, or overtaking, and which rule number governs it?

Buoyage: the IALA system

Europe (including the UK) uses IALA Region A. The golden rule is 'red to port, green to starboard' when returning from sea (heading upstream or into harbour). This is the reverse of Region B (Americas), so if you ever cruise abroad, check which region you are in before trusting colours.

Lateral marks

Lateral marks show the edges of a channel.

• Port hand marks: red, can-shaped (flat-topped) or with a can topmark, odd numbers increasing into harbour.
• Starboard hand marks: green, conical (pointed) or with a cone topmark, even numbers increasing into harbour.
• Direction of buoyage matters more than compass direction - it is the conventional direction, shown on charts by a bold magenta arrow, usually flooding tide into a harbour or estuary.

Cardinal marks

Cardinal marks indicate where the safest, deepest water lies relative to the mark itself - not a direction to travel. They are black and yellow with two black cone topmarks, and use white quick or very quick flashing lights so you can identify them at night.

• North: topmarks point up, both up; light is continuous quick/very quick flashing.
• South: topmarks point down, both down; light is 6 flashes + long flash every 10 or 15 seconds (think 6 = south, like a clock face).
• East: topmarks point away from each other (base to base); light is 3 flashes.
• West: topmarks point towards each other (point to point); light is 9 flashes.

Pass on the named side - eg pass north of a North cardinal mark.

Other marks

• Isolated danger marks: black with a single red band, two black spheres topmark, white group flash (2) every period, marks an isolated hazard with safe water all around.
• Safe water marks: red and white vertical stripes, single red sphere topmark, isophase/occulting/long flash or Morse 'A' light, marks the centre of a channel or landfall.
• Special marks: yellow, optional yellow 'X' topmark, yellow light if lit, mark cables, spoil grounds, racing areas or other features - not for navigation.
• New danger marks: mimic the relevant IALA mark (or a pillar/spar with blue and yellow stripes and a Q flash), may be doubled up until charted.

Pilotage

Pilotage means navigating using visible landmarks, transits, clearing bearings and depth rather than relying only on GPS. Before departure, plan your route against the chart, note hazards, tidal set and safe water. Use transits (two fixed objects in line) to check you are holding a safe track, and clearing bearings to stay clear of danger. Always have a back-up plan if electronics fail.

Common mistakes

• Mixing up Region A and B colours when boating abroad.
• Confusing cardinal topmark shapes - remember 'points to danger, cones to safety' as a memory aid.
• Forgetting that cardinal marks tell you where the danger is relative to the mark, not a fixed compass direction to steer.
• Treating GPS as infallible instead of cross-checking with visual pilotage.

Why charts matter

A nautical chart is your primary tool for safe passage planning and pilotage. It shows depths, hazards, buoyage, and land features so you can work out where you are and where it is safe to go. Always use the most up-to-date chart available - hazards and buoyage change.

Chart datum and depths

• Depths on a chart are shown in metres below Chart Datum (CD), which is usually close to Lowest Astronomical Tide (LAT).
• Chart Datum is the level below which the tide rarely falls, so charted depths are the minimum you can normally expect.
• Drying heights (areas that uncover at low tide) are underlined on the chart and given as a height ABOVE chart datum.
• Heights of land features, lights, and bridges are shown ABOVE Mean High Water Springs (MHWS), a different reference level - do not confuse the two.

Latitude and longitude

• Latitude lines run parallel to the Equator (0 degrees) and are numbered North or South up to 90 degrees at the poles.
• Longitude lines run through the poles and are numbered East or West of the Greenwich Meridian (0 degrees) up to 180 degrees.
• Position is always given latitude first, then longitude, e.g. 50 degrees 30 minutes N, 001 degrees 15 minutes W.
• One minute of latitude equals one nautical mile - this is why the latitude scale (side of chart) is used for measuring distance, never the longitude scale at the top or bottom.

Compass directions

• True North (the geographic North Pole) differs from Magnetic North (where a compass points) by an amount called variation, shown on the chart's compass rose and changing slowly year by year.
• Deviation is a separate error caused by magnetic material or electronics on your own boat, and varies by heading.
• The rule for converting compass to true (or back) is often remembered as 'True Virgins Make Dull Company' (True, Variation, Magnetic, Deviation, Compass) - add west errors, subtract east errors when going from compass to true.

Position fixing

• A position can be fixed using GPS, by taking two or more bearings of known charted objects, or by using a single object's bearing plus a depth or distance.
• Always cross-check GPS against a visual or chart-based fix where possible - electronics can fail or mislead.
• Plot your position clearly on the chart with time noted, so you can track progress and detect drift or tidal set.

Common mistakes

• Reading distance off the longitude (top/bottom) scale instead of the latitude (side) scale.
• Confusing drying height (above chart datum) with a charted depth (below chart datum).
• Forgetting to apply variation when converting between compass and true courses.
• Using an out-of-date chart or missing a Notice to Mariners correction.

Why safety equipment matters

The ICC (International Certificate of Competence) theory test expects you to know what safety kit a powerboat must carry, how to use it, and the procedures for common emergencies. Examiners test both the list of equipment and the reasoning behind it - carrying gear is useless if the crew does not know how to use it.

Lifejackets and buoyancy aids

• Every person on board should wear a properly fitted lifejacket or buoyancy aid whenever there is a risk of falling in, especially at speed or in open water.
• Lifejackets (150N or 275N) are designed to turn an unconscious casualty face-up; buoyancy aids (50N) support a conscious swimmer but will not turn them over.
• Check the lifejacket has a working light, whistle and, ideally, a crotch strap so it cannot ride up over the head.
• A common mistake is assuming children's lifejackets are just smaller adult ones - they must be sized to the child's actual weight in kilograms.

Kill cord (engine cut-off)

• The kill cord must be attached to the driver's wrist or lifejacket at all times when underway - if the driver is thrown from the helm, the engine cuts out immediately.
• Never loop the kill cord around a fixed point or leave it slack near the helm - it must pull free the instant the driver leaves the seat.
• Kill cord failure to disconnect is a leading cause of 'circle of death' accidents, where an unmanned boat circles back and strikes people in the water.

Fire, flares and other essential kit

• Carry a fire extinguisher suitable for fuel and electrical fires, fitted where it is reachable without going near the engine bay.
• Carry in-date visual distress signals (flares) appropriate to your cruising area - coastal trips need more than sheltered inland waters.
• A first aid kit, anchor with sufficient warp, torch, and a means of raising the alarm (VHF radio or phone in a waterproof pouch) should always be aboard.

Emergency procedures

• Know the man overboard drill: shout 'man overboard', point continuously at the casualty, cut power, and approach from downwind/downtide with the propeller stopped near the casualty.
• Before departure, always check the weather forecast, fuel levels (rule of thirds: out, back, reserve) and that all safety kit is present and in date.
• File a passage plan or tell someone ashore your route and expected return time.

Common mistakes

• Treating the kill cord as optional at low speed - it should be worn at all times underway.
• Overloading the boat beyond its plated capacity, reducing freeboard and stability.
• Storing flares and first aid kits somewhere inaccessible in an emergency.

Why weather matters afloat

Weather drives most powerboat incidents - not the boat. Before you slip lines, check a proper forecast (Met Office inshore waters forecast, or a marine app like PredictWind or Windy) and compare it against what you can actually see and feel. Never rely on a phone signal alone once you are out - conditions change faster than forecasts update.

The Beaufort scale - know it cold

The Beaufort scale runs 0 to 12 and is the universal way sailors describe wind strength.

• Force 0: calm, glassy water
• Force 3: gentle breeze, 7-10 knots, small wavelets, crests begin to break
• Force 4: moderate breeze, 11-16 knots, small waves, fairly frequent white horses - many small-boat trips get cancelled here
• Force 6: strong breeze, 22-27 knots, large waves form, spray likely - open small powerboats should not be out
• Force 8: gale, 34-40 knots, moderately high waves, foam blown in streaks

Learn the knot ranges for Forces 3 to 6 - that is the band most theory questions and real trip decisions sit in.

Wind against tide

When wind blows against the tidal stream, waves stack up short, steep and close together - far worse than the wind strength alone suggests. This is one of the most dangerous and commonly underestimated combinations in coastal boating, especially over shallow bars and headlands.

Fog

Reduces visibility below 1000 metres (international definition). If fog closes in: slow down, post a lookout, sound fog signals, use radar/AIS if fitted, and navigate by compass and GPS rather than sight. Never increase speed to 'get through it faster'.

Reading the sky and barometer

• A falling barometer usually signals an approaching low-pressure system and worsening weather.
• A rising barometer generally means improving, more settled conditions.
• Mares' tails (wispy high cirrus) can be an early sign of a front arriving within 24-48 hours.
• Dark, building cumulonimbus cloud signals squalls, heavy rain and thunderstorms - get off the water.

Common mistakes

• Checking the forecast once at home and not rechecking before departure.
• Ignoring wind-against-tide because the wind number alone looks moderate.
• Treating land-based forecasts as accurate for open water, where wind is usually stronger with no obstructions.
• Underestimating how quickly a Force 3 can build to Force 6 in coastal waters.

Why paperwork matters abroad

Once you take a powerboat outside UK waters the rules change country by country. The ICC (International Certificate of Competence) exists precisely so you have one recognised qualification accepted across most of Europe and beyond, but a certificate alone is not enough - you must carry the right documents and know the local rules apply, not UK ones.

The ICC itself

• The ICC is issued in the UK by the RYA (delegated by the government) under a UN/ECE framework.
• It comes in categories - inland waters and coastal/tidal waters - and separate endorsements for sail and power.
• Power endorsement is split by boat length and speed, broadly under and over 10 metres, plus a personal watercraft (PWC) endorsement if riding a jet ski.
• It is valid because many countries have signed the underlying international resolution (Resolution 40), but not all - always check the specific country's requirements before you go, since some (eg parts of the Mediterranean) demand extra local tests or licences.

Documents to carry on board

• Original ICC (a photocopy is not normally accepted).
• Passport or photo ID.
• Proof of boat ownership or a charter agreement / bareboat charter certificate if you are hiring.
• Registration document for the vessel (eg SSR - Small Ships Register - for UK boats, or the country's flag registration).
• Valid third-party liability insurance certificate - many countries make this a legal requirement, unlike the UK where it is only strongly recommended.
• VAT/import status paperwork for the vessel where relevant (proves the boat's tax status in EU waters).

Common mistakes

• Assuming a UK Powerboat Level 2 certificate alone is enough abroad - it isn't; you need the ICC.
• Leaving insurance documents at home - several countries can detain a boat without proof of cover.
• Forgetting that speed limits, alcohol limits, and distance-from-shore rules are set nationally and can be stricter than UK ones.
• Not checking VHF radio licensing - a UK Short Range Certificate (SRC) plus a ship radio licence is usually still required, and some countries want proof of it too.
• Believing the ICC never expires - check the specific document; some versions/countries expect periodic renewal or revalidation.

Practical approach

Before any trip abroad, research the destination country's maritime authority website (or ask the charter company) for current rules, since local law always overrides what you're used to in the UK. Keep all documents together, ideally with copies stored separately from the originals.