Practice · 118 flashcards · 7 decks

COLREGs quiz: 118 flashcards with spaced repetition

Seven decks: who gives way, lights, shapes, sound signals, definitions, numbers, fog and channels. Cards on lights show the diagram, cards on signals play the sound.

The better you know a card, the later it comes back: ten minutes, one day, three days, a week, sixteen days, thirty-five days, ninety days. That schedule is the whole point of spaced repetition: you meet each fact again just before you would have forgotten it, which is far cheaper than rereading the rules.

Cards in the lights deck draw the configuration from three angles and ask you to name her. Cards in the shapes deck draw the ball, cone, diamond or cylinder. Cards in the sound deck play the whistle so you learn it by ear. Progress is kept in your browser, nothing is sent anywhere, and the page works with no connection once you add it to your home screen.

Prefer reading first? Start with the 38 rules in plain English, then the lights and shapes and the sound signals.

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Who gives way 20

Two power-driven vessels are crossing. Who gives way and how?

The one that has the other on her own starboard side. She turns to starboard and passes astern: crossing ahead is not allowed.

Rule 15.

At night you see only a red sidelight on your starboard side. What do you do?

Red means you see her port side, she is crossing right to left ahead of you. You give way: reduce speed and/or turn to starboard.

Rule 15. Mnemonic: red means stop, green means go.

At night you see only a green sidelight on your starboard side. What do you do?

You see her starboard side, so she gives way. Keep your course and speed, but watch her: if she does nothing, act yourself.

Rule 15 and 17.

Two power-driven vessels are meeting head on. Who turns and which way?

Both to starboard, passing port to port. Not one of them, each.

Rule 14 (a).

How do you recognise a head-on situation at night?

Her lights are ahead or nearly ahead, and you see her masthead lights in a line and/or both sidelights. By day, the corresponding aspect.

Rule 14 (b). In doubt, assume it exists.

You are overtaking another vessel. Who is responsible for keeping clear?

The overtaking vessel keeps out of the way and stays bound until the other is finally past and clear.

Rule 13. It overrides the crossing rules.

Geometry of overtaking: from which bearing are you the overtaking vessel?

From more than 22.5 degrees abaft her beam: at night you see only her sternlight and neither sidelight.

Rule 13 (b).

You cannot tell whether this is overtaking or crossing. What do you do?

Assume it is overtaking and keep out of the way.

Rule 13 (c). Doubt is always resolved on the side of caution.

Give the order of responsibilities under rule 18, top down.

Not under command, restricted in ability to manoeuvre, engaged in fishing, sailing, power-driven. Separately: all but the first two avoid impeding a vessel constrained by her draught.

Rule 18. Mnemonic: cannot, will not, fisher, sail, power.

Two sailing vessels on different tacks. Who keeps clear?

The one on the port tack (wind on her port side).

Rule 12 (a) (i).

Two sailing vessels on the same tack. Who keeps clear?

The vessel to windward keeps clear of the vessel to leeward.

Rule 12 (a) (ii).

You are on port tack and cannot determine the tack of a vessel to windward. What then?

You keep out of her way.

Rule 12 (a) (iii).

What must the stand-on vessel do?

Keep her course and speed. But once it is apparent the other is not giving way she may manoeuvre, and when collision cannot be avoided by the other's action alone she shall.

Rule 17 (a), (b).

Acting alone in a crossing situation, which way must you not turn?

To port, if the other vessel is on your own port side.

Rule 17 (c).

How must the give-way vessel act?

Early and substantially, so as to keep well clear: one large, obvious manoeuvre rather than a string of small ones.

Rule 16 and 8 (b).

Which wins: the order of rule 18, or the rules on channels, lanes and overtaking?

Rules 9, 10 and 13 win. In a channel and a traffic lane a sailing or fishing vessel must not impede a big ship, and the overtaking vessel always keeps clear.

The opening words of rule 18.

A seaplane on the water and a WIG craft in flight near the surface: how do they act?

Both keep well clear of all vessels and avoid impeding their navigation. On the water the WIG craft is an ordinary power-driven vessel.

Rule 18 (e), (f).

You are unsure whether risk of collision exists. How do you treat it?

Treat it as existing and act. The sign: the compass bearing of the approaching vessel does not appreciably change.

Rule 7 (a), (d).

You are giving way. How large must the manoeuvre be?

Large enough to be readily apparent by eye or on radar. A succession of small alterations is forbidden.

Rule 8 (b).

What does the duty «not to impede» another vessel mean?

Taking early action to leave enough sea room for her safe passage. The duty does not lapse when risk of collision develops.

Rule 8 (f).

Lights 36

Who is this and how do you behave?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel restricted in her ability to manoeuvre: all-round red, white, red. With way on she also shows masthead lights, sidelights and a sternlight. Everyone gives way to her except a vessel not under command.

Rule 27 (b).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel not under command making way through the water: two all-round reds, sidelights and a sternlight. No masthead lights, which is the key difference from a vessel restricted in ability to manoeuvre.

Rule 27 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel not under command with no way on: just two all-round reds. Two balls by day.

Rule 27 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel constrained by her draught: three all-round reds together with the lights of a power-driven vessel. A cylinder by day.

Rule 28.

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel engaged in trawling: all-round green over white. She is making way, hence the sidelights and sternlight.

Rule 26 (b).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel fishing other than trawling: all-round red over white, nets or lines.

Rule 26 (c).

Who is this and which side do you pass?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A fishing vessel with gear extending more than 150 m: red over white plus an all-round white towards the gear. Pass on the opposite side.

Rule 26 (c) (ii).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A pilot vessel on pilotage duty: all-round white over red. Mnemonic: white over red, pilot ahead.

Rule 29 (a).

Who is this and what must you not do?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel engaged in mine clearance: three all-round greens (one at the foremast head, two at the yardarm ends). Do not approach within 1000 m.

Rule 27 (f).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel at anchor of 50 m or more: an all-round white forward and a second, lower, at the stern. No sidelights and no sternlight.

Rule 30 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel aground: anchor lights plus two all-round reds. Three balls by day.

Rule 30 (d).

Who is this and what is dangerous between them?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A towing vessel with a tow up to 200 m: two masthead lights in a vertical line and a yellow towing light above the sternlight. There is an object on a wire astern of her, never pass between.

Rule 24 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A towing vessel with a tow longer than 200 m: three masthead lights in a vertical line, a diamond by day.

Rule 24 (a) (i).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel pushing ahead or towing alongside: two masthead lights, sidelights and a sternlight, but no yellow towing light.

Rule 24 (c).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel being towed: sidelights and a sternlight with no masthead lights. Look ahead of her for the tug with two whites in a column.

Rule 24 (e).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A sailing vessel underway: sidelights and a sternlight only, no masthead light.

Rule 25 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A sailing vessel with the optional lights: all-round red over green at the masthead. Do not confuse with white over red (pilot) or red over white (fishing).

Rule 25 (c).

Who is this and what shape is compulsory by day?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel under sail with her engine running: the lights of a power-driven vessel, and a cone point down by day.

Rule 25 (e).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A power-driven vessel under 12 m: an all-round white instead of masthead and sternlight, plus sidelights.

Rule 23 (d) (i).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A power-driven vessel of 50 m or more: two masthead lights in line (the after one higher), sidelights, sternlight.

Rule 23 (a).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

An air-cushion vessel in non-displacement mode: the normal set plus an all-round flashing yellow.

Rule 23 (b).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A WIG craft taking off, landing or in flight near the surface: the normal set plus a high-intensity all-round flashing red.

Rule 23 (c).

Who is this and which side may you pass?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A dredger with an obstruction: red, white, red plus two reds on the obstructed side and two greens on the side you may pass. Go where the greens are.

Rule 27 (d).

Who is this and what is nearby?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

Diving operations from a small vessel: red, white, red and a rigid flag «A». There are people in the water, passing close at speed is dangerous.

Rule 27 (e).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel restricted in ability to manoeuvre at anchor: red, white, red plus the anchor lights.

Rule 27 (b) (iv).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

A vessel at anchor under 50 m: a single all-round white where it can best be seen.

Rule 30 (b).

Who is this?

seen from ahead (her starboard side on your left)
seen from her starboard beam
seen from astern

Towing that severely restricts the ability to deviate: the towing lights plus red, white, red.

Rule 27 (c).

From astern, what can you see of a vessel underway and what can you not?

You see the white sternlight (135 degrees) and any all-round lights. You cannot see the masthead lights (225 degrees forward) or the sidelights (112.5 degrees forward).

Rule 21.

You see a single white light and no colours. What can it be?

Either you are in the stern sector of a vessel underway (her sternlight), or it is a vessel at anchor or a small craft with an all-round white. Tell them apart by movement and by the second white light.

Rule 21, 23 (d), 30.

The light sectors: masthead, sidelights, sternlight, all-round?

Masthead 225 degrees, sidelights 112.5 each, sternlight 135, all-round 360.

Rule 21. 225 plus 135 makes 360.

What does a yellow light above a white sternlight mean?

A towing light: she is towing on a wire.

Rule 21 (d) and 24 (a) (iv).

When are lights shown and when are shapes shown?

Lights from sunset to sunrise, and by day in restricted visibility or whenever necessary. Shapes by day.

Rule 20.

A vessel not under command is making way. Which lights are added and which are not?

Sidelights and a sternlight are added. Masthead lights are not, unlike a vessel restricted in ability to manoeuvre.

Rule 27 (a) (iii) versus 27 (b) (iii).

May a fishing vessel show any lights other than those of rule 26?

No. A vessel engaged in fishing shows only the rule 26 lights, underway or at anchor. A vessel not fishing must not show them at all.

Rule 26 (a), (e).

How do you tell white-over-red from red-over-white?

White over red is a pilot. Red over white is fishing other than trawling. The order changes the meaning completely.

Rule 29 (a) and 26 (c).

How do you tell green-over-white from red-over-white?

Green over white: trawling, she is dragging gear. Red over white: any other kind of fishing.

Rule 26 (b), (c).

Shapes 12

What do two cones with their apexes together mean?

By day

A vessel engaged in fishing: trawling or any other fishing.

Rule 26 (b) (i), (c) (i).

What do ball, diamond, ball in a vertical line mean?

By day

A vessel restricted in her ability to manoeuvre: the daytime equivalent of red, white, red.

Rule 27 (b) (ii).

What do two balls in a vertical line mean?

By day

A vessel not under command: the daytime equivalent of two all-round reds.

Rule 27 (a) (ii).

What does a cylinder mean?

By day

A vessel constrained by her draught: the daytime equivalent of three all-round reds.

Rule 28.

What do three balls in a vertical line mean?

By day

A vessel aground.

Rule 30 (d) (ii).

What does a single ball in the fore part mean?

By day

A vessel at anchor.

Rule 30 (a) (i).

What does a cone with the point down mean?

By day

She is under sail and using her engine, so by the rules she is a power-driven vessel.

Rule 25 (e).

What does a cone point up on a fishing vessel mean?

By day

Her gear extends more than 150 metres in that direction.

Rule 26 (c) (ii).

What does a diamond shape on a tug mean?

By day

The length of tow exceeds 200 metres. Both the towing and the towed vessel show it.

Rule 24 (a) (v), (e) (iii).

What does a rigid flag «A» at least a metre high mean?

By day

Diving operations from a vessel that cannot show the full set of lights and shapes.

Rule 27 (e) (ii).

What do two balls on one side and two diamonds on the other mean on a dredger?

By day

The balls mark the side with the obstruction. The diamonds mark the side you may pass.

Rule 27 (d).

What do three balls mean on a vessel showing ordinary running lights by day?

By day

A mine clearance vessel (balls at the foremast head and yardarm ends): do not come within 1000 m. Three balls in a vertical line would mean aground.

Rule 27 (f) and 30 (d).

Sound signals 16

One short blast. What does it mean?

«I am altering my course to starboard».

Rule 34 (a).

Two short blasts. What do they mean?

«I am altering my course to port».

Rule 34 (a).

Three short blasts. What do they mean?

«I am operating astern propulsion».

Rule 34 (a).

At least five short and rapid blasts. What does that mean?

«I do not understand your intentions» or «I doubt whether you are taking sufficient action». Sounded immediately, and may be joined by flashes.

Rule 34 (d). It is not a distress signal.

Two prolonged and one short blast. Where and what is it?

In a narrow channel or fairway only: «I intend to overtake you on your starboard side». Two prolonged and two short means on your port side.

Rule 34 (c) (i).

Prolonged, short, prolonged, short. Who sounds it and why?

The vessel being overtaken in a channel: «agreed, come through», and she then takes steps to permit safe passing.

Rule 34 (c) (ii) and 9 (e) (i).

In fog, one prolonged blast every two minutes. Who is it?

A power-driven vessel making way through the water.

Rule 35 (a).

In fog, two prolonged blasts about two seconds apart. Who is it?

A power-driven vessel underway but stopped, with no way on.

Rule 35 (b).

In fog, one prolonged and two short blasts. Who can be sounding that?

Not under command, restricted in ability to manoeuvre, constrained by draught, sailing, fishing, towing or pushing.

Rule 35 (c).

In fog, one prolonged and three short blasts. Who is it?

A vessel towed, or the last vessel of the tow, when manned.

Rule 35 (e).

How do a vessel at anchor and a vessel aground sound in fog?

At anchor, rapid ringing of the bell for about 5 seconds every minute (from 100 m, bell forward and gong aft). Aground, the same plus three separate strokes before and after.

Rule 35 (g), (h).

You are approaching a bend in a channel where you cannot be seen. What signal?

One prolonged blast. Any vessel round the bend within hearing must answer with one prolonged blast.

Rule 9 (f) and 34 (e).

How long is a short blast and how long is a prolonged blast?

Short about 1 second, prolonged 4 to 6 seconds.

Rule 32 (b), (c).

What sound equipment is required by length?

From 12 m a whistle, from 20 m also a bell, from 100 m also a gong. Under 12 m, any means of making an efficient sound signal.

Rule 33.

Which sound signal means distress?

Continuous sounding of any fog-signalling apparatus. Plus the Annex IV signals: red parachute flare, orange smoke, SOS, «Mayday», flags N and C.

Rule 37.

Four short blasts. Who sounds them?

A pilot vessel engaged on pilotage duty, as an identity signal.

Rule 35 (k).

Definitions 12

What does «underway» mean?

Not at anchor, not made fast to the shore, not aground. A vessel drifting with her engine stopped is underway too.

Rule 3 (i).

When are vessels «in sight of one another»?

Only when one can be observed visually from the other. A radar contact is not in sight, and rules 11 to 18 then do not apply.

Rule 3 (k).

How does «not under command» differ from «restricted in ability to manoeuvre»?

The first cannot manoeuvre through exceptional circumstance (breakdown). The second cannot because of the nature of her work: cable, dredging, replenishment underway, aircraft operations, mine clearance, a heavy tow.

Rule 3 (f), (g).

What is a «vessel constrained by her draught»?

A power-driven vessel only, whose draught in relation to the available depth and width of navigable water severely restricts her ability to deviate from her course.

Rule 3 (h).

Which kind of fishing does not make a vessel «engaged in fishing»?

Fishing with trolling lines or other apparatus that does not restrict manoeuvrability.

Rule 3 (d).

What counts as «restricted visibility»?

Fog, mist, falling snow, heavy rainstorms, sandstorms and any similar cause.

Rule 3 (l).

When do the rules allow you to depart from them?

When it is necessary to avoid immediate danger. At the same time they do not exonerate anyone who neglected the ordinary practice of seamen.

Rule 2 (a), (b).

What is a «towing light»?

A yellow light with the same characteristics as a sternlight (135 degrees), shown above the sternlight of a towing vessel.

Rule 21 (d).

How is a «flashing light» defined?

A light flashing at regular intervals at a frequency of 120 flashes or more per minute.

Rule 21 (f).

What is a «composite unit» and what lights does it show?

A pushing vessel and a vessel pushed ahead rigidly connected. They show the ordinary lights of a power-driven vessel under rule 23.

Rule 24 (b).

What is an inshore traffic zone and who may use it?

The strip between the coast and a traffic separation scheme. It is used by vessels under 20 m, sailing vessels, vessels engaged in fishing, and any vessel going to or from a port, installation or pilot station inside the zone.

Rule 10 (d).

What is a WIG craft and how does she act?

A multimodal craft that in her main operating mode flies close to the surface using surface-effect action. Taking off, landing and in flight she keeps well clear of all vessels; on the water she is a power-driven vessel.

Rule 3 (m) and 18 (f).

Numbers 12

Where does the 22.5 degree angle in the rules come from?

It is the limit abaft the beam where the sidelights and masthead light stop. Beyond it only the sternlight shows, and that is the overtaking zone.

Rule 21 (a), (b) and 13 (b).

Light ranges for a vessel of 50 m or more?

Masthead 6 miles; sidelights, sternlight, towing light and all-round lights 3 miles.

Rule 22 (a).

Light ranges for a vessel from 12 to 50 m?

Masthead 5 miles (3 miles if under 20 m), the rest 2 miles.

Rule 22 (b).

Light ranges for a vessel under 12 m?

Masthead 2 miles, sidelights 1 mile, sternlight, towing light and all-round lights 2 miles.

Rule 22 (c).

Which length of tow changes the lights and shapes?

200 metres, measured from the stern of the towing vessel to the after end of the tow: three masthead lights instead of two, plus a diamond shape.

Rule 24 (a).

From what length of gear does a fishing vessel need an extra light?

When the gear extends more than 150 metres horizontally: an all-round white or a cone point up towards it.

Rule 26 (c) (ii).

How close is it dangerous to approach a mine clearance vessel?

Within 1000 metres.

Rule 27 (f).

From what length is a second masthead light compulsory, and deck lighting at anchor?

Second masthead light from 50 m. Deck lighting at anchor is required for vessels over 100 m.

Rule 23 (a) (ii) and 30 (c).

At what intervals are fog signals sounded?

On the whistle, not more than every 2 minutes. The anchor bell, not more than every minute, ringing for about 5 seconds.

Rule 35.

Which lengths are exempt from rule 27 lights and from the aground shapes?

Under 12 m: exempt from rule 27, except diving operations. Under 12 m aground: exempt from the two reds and three balls. Under 7 m at anchor away from channels: exempt from the anchor light.

Rule 27 (g), 30 (e), (f).

How many flashes per minute for a flashing light, and how long is a manoeuvring light flash?

A flashing light, 120 or more per minute. A manoeuvring flash about 1 second, about 1 second between flashes, not less than 10 seconds between signals.

Rule 21 (f) and 34 (b).

At what breadth and length does an inconspicuous tow need extra lights?

From 25 metres in breadth, two more all-round whites at the sides. Over 100 metres in length, lights spaced so the gap never exceeds 100 metres.

Rule 24 (g).

Fog and channels 10

In fog a target is detected by radar alone, forward of the beam. Which manoeuvre is barred?

An alteration to port for a vessel forward of the beam (other than one being overtaken). Also altering towards a vessel abeam or abaft the beam.

Rule 19 (d).

In fog you hear a fog signal apparently forward of your beam. What must you do?

Reduce speed to the minimum at which you can be kept on course, take all your way off if necessary, and navigate with extreme caution until the danger is over.

Rule 19 (e).

What is required of the engines in restricted visibility?

A power-driven vessel keeps her engines ready for immediate manoeuvre and her speed safe for the conditions.

Rule 19 (b).

Which side of a narrow channel must you keep to?

The outer limit that lies on your starboard side, as near to it as is safe and practicable.

Rule 9 (a).

Who must not impede a vessel that can navigate only inside the channel?

A vessel under 20 m, a sailing vessel and a vessel engaged in fishing. A fishing vessel must not impede any vessel in the fairway.

Rule 9 (b), (c).

How does overtaking work in a narrow channel?

Only by agreement: the overtaking vessel signals her intention, the other agrees and takes steps to permit safe passing. The agreement does not release her from rule 13.

Rule 9 (e).

How do you cross a traffic lane correctly?

On a heading as nearly as practicable at right angles to the general direction of flow, and ideally not crossing at all.

Rule 10 (c).

Where must you not anchor?

In a narrow channel (if it can be avoided) and in a traffic separation scheme or near its ends.

Rule 9 (g) and 10 (g).

How do you join and leave a traffic lane?

At the ends of the lane. From either side, at as small an angle as practicable to the direction of flow.

Rule 10 (b) (iii).

What do you do if you cannot read the intentions of a vessel crossing the fairway?

Sound at least five short and rapid blasts: the doubt signal of rule 34 (d).

Rule 9 (d) and 34 (d).

All 38 rules, one page each

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