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COLREGs quiz: lights, shapes, sounds and buoys.
Free drills on the signals every MCA deck oral asks about: vessel lights at night, day shapes, manoeuvring and fog signals, and IALA buoyage. No sign-up, nothing stored — ten questions a round, reshuffled every time.
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Every signal in the quiz
The answers, with the rule each comes from — for revision after a round. The drawings show the identifying signature (the lights or shapes on the mast, sidelights either side), not a true view from one bearing.
Lights and shapes
- Power-driven vessel, 50 m or more, underway
- Two masthead lights (after one higher), sidelights and a sternlight. A PDV under 50 m may show one masthead light. Rule 23(a)
- Power-driven vessel, 12–50 m, underway
- One masthead light, sidelights and a sternlight. Rule 23(a)
- Power-driven vessel, under 12 m
- May show one all-round white light and sidelights. Rule 23(d)
- Air-cushion vessel (hovercraft) in non-displacement mode
- A power-driven vessel's lights plus an all-round flashing yellow light. Rule 23(b)
- Sailing vessel underway
- Sidelights and a sternlight, no masthead light. Under 20 m these may combine in one tricolour lantern. Rule 25(a)
- Sailing vessel with optional masthead lights
- Optional two all-round lights at the masthead, red over green (not with the combined tricolour lantern). Rule 25(c)
- Vessel under sail and power (motorsailing)
- Shows power-driven lights; by day a cone, apex downward. Treated as a power-driven vessel for the steering rules. Rule 25(e)
- Vessel trawling, making way
- All-round green over white; by day two cones, apexes together. Sidelights and sternlight when making way. Rule 26(b)
- Vessel fishing (not trawling), making way
- All-round red over white; by day two cones, apexes together. Rule 26(c)
- Vessel not under command (NUC), not making way
- Two all-round red lights in a vertical line; by day two black balls. Never shows masthead lights. Rule 27(a)
- Vessel not under command (NUC), making way
- Two all-round red lights plus sidelights and sternlight when making way through the water. Rule 27(a)
- Vessel restricted in her ability to manoeuvre (RAM), not making way
- Three all-round lights in a vertical line: red, white, red. By day: ball, diamond, ball. Rule 27(b)
- Vessel restricted in her ability to manoeuvre (RAM), making way
- Red-white-red plus masthead light(s), sidelights and sternlight when making way. Rule 27(b)
- Vessel constrained by her draught
- Power-driven lights plus three all-round red lights in a vertical line; by day a cylinder. Rule 28
- Pilot vessel on pilotage duty, underway
- All-round white over red at the masthead ('white over red, pilot ahead'), with sidelights and sternlight underway. Rule 29(a)
- Power-driven vessel towing, tow not exceeding 200 m
- Two masthead lights in a vertical line, a yellow towing light above the sternlight, sidelights and sternlight. Rule 24(a)
- Power-driven vessel towing, tow exceeding 200 m
- Three masthead lights in a vertical line, a yellow towing light, sidelights and sternlight; by day a diamond shape. Rule 24(a)
- Vessel at anchor, 50 m or more
- A forward anchor light and a lower one aft; 100 m or more must illuminate her decks. By day, one ball forward. Rule 30(a)
- Vessel at anchor, under 50 m
- One all-round white light where it can best be seen; by day one black ball forward. Rule 30(b)
- Vessel aground
- Anchor light(s) plus two all-round red lights in a vertical line; by day three black balls in a vertical line. Rule 30(d)
Sound signals
- ● One short blast — I am altering my course to starboard
- Manoeuvring signal between vessels in sight of one another. Rule 34(a)
- ●● Two short blasts — I am altering my course to port
- Manoeuvring signal between vessels in sight of one another. Rule 34(a)
- ●●● Three short blasts — I am operating astern propulsion
- Manoeuvring signal between vessels in sight of one another. Rule 34(a)
- ●●●●● Five or more short, rapid blasts — Doubt — I do not understand your intentions / take action
- The 'wake-up' signal when you doubt the other vessel's intentions or actions. Rule 34(d)
- ▬ One prolonged blast (in fog) — A power-driven vessel making way
- Restricted-visibility signal, at intervals of not more than 2 minutes. Rule 35(a)
- ▬ ●● One prolonged + two short (in fog) — A NUC, RAM, constrained, sailing, fishing or towing vessel
- Restricted-visibility signal common to all these vessel types. Rule 35(c)
- ▬ One prolonged blast (at a bend) — Warning when nearing a blind bend
- Answered by one prolonged blast from any vessel within hearing round the bend. Rule 34(e)
IALA buoyage
- Port-hand lateral mark (Region A)
- Red can; red light. Keep it to port entering harbour ('red to port, Region A'). IALA R1001 §2.1
- Starboard-hand lateral mark (Region A)
- Green conical; green light. Keep it to starboard entering harbour (Region A). IALA R1001 §2.1
- Port-hand lateral mark (Region B)
- Region B reverses the laterals: port-hand marks are green ('red right returning'). IALA R1001 §2.1
- Starboard-hand lateral mark (Region B)
- Region B: starboard-hand marks are red. IALA R1001 §2.1
- Preferred channel to starboard (Region A)
- Modified port-hand mark (red with a green band); keep to port, preferred channel to starboard. Light Fl(2+1). IALA R1001 §2.1.5
- North cardinal mark
- Black over yellow; two black cones pointing up. White VQ or Q. Pass to the north. IALA R1001 §2.2
- East cardinal mark
- Black with a yellow band; cones base-to-base. White VQ(3) 5s / Q(3) 10s. Pass to the east. IALA R1001 §2.2
- South cardinal mark
- Yellow over black; cones pointing down. White VQ(6)+LFl 10s / Q(6)+LFl 15s. Pass to the south. IALA R1001 §2.2
- West cardinal mark
- Yellow with a black band; cones point-to-point ('wineglass'). White VQ(9) 10s / Q(9) 15s. Pass to the west. IALA R1001 §2.2
- Isolated danger mark
- Black with red band(s); two black spheres. White Fl(2). Navigable water all around. IALA R1001 §2.3
- Safe water mark
- Red and white vertical stripes; single red sphere. White Iso/Oc/LFl 10s/Morse A. Mid-channel / landfall. IALA R1001 §2.4
- Special mark
- Yellow; yellow 'X' (St Andrew's cross) topmark; yellow light. Marks a special area, not a hazard. IALA R1001 §2.5
- Emergency Wreck Marking Buoy
- Blue and yellow vertical stripes; upright yellow cross. Alternating blue/yellow light. Marks a new, uncharted wreck. IALA R1001 §2.6
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