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RulesAtSea

Free boating rules practice

COLREGs quiz: practise collision rules and vessel duties

Read an authored encounter and its opening diagram, then choose an action under the International COLREGs. Explain the give-way and stand-on duties before checking your answer. Continue into the simulator to observe the encounter and replay the decision.

Try the quizRead the colregs and collision avoidance guide

7 concepts · explained answers · no account needed

Practice scope: Free, original supplementary practice using International COLREGs / IRPCS and separately labeled IALA Regions A and B. These are authored learning questions, not official examination questions or a qualification. Use the full applicable rules, current charts and local requirements on the water. International COLREGs / IRPCS. Apply the rule to the visibility, vessel operation and waterway in the situation.

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No account or WebGL needed. Scores last for this page visit. Original teaching graphics and synthesized signals support the questions; the simulator adds movement and replay.

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Question topics and explained answers

The quiz draws from these 7 concepts. Recognition questions may change the viewing aspect, whistle or day/night cue. Open a topic to review its explanation and governing reference.

A vessel to starboard

Which action best keeps you clear?

You are heading north under power. Another power-driven vessel is approaching from your starboard side. Both vessels are in sight of one another.

Alter clearly to starboard You have the other vessel on your starboard side. In this open-water crossing, you must keep out of the way and, if circumstances admit, avoid crossing ahead. A clear starboard alteration is the authored example of passing astern.

Rules 15 & 16 · Crossing and give-way action · US Coast Guard · International Navigation Rules
Meeting head-on

How should the two vessels pass?

Another power-driven vessel is approaching on a reciprocal course. The situation involves risk of collision, with open water on either side.

Alter to starboard Both power-driven vessels should alter course to starboard so they pass port side to port side. The other vessel’s matching action is explicitly authored in this replay.

Rule 14 · Head-on situation · US Coast Guard · International Navigation Rules
Power meets sail

Which vessel should keep out of the way?

You are under power. A sailing vessel, using sails only, crosses from your port side. This is open water, outside a narrow channel or traffic separation scheme, and you are not overtaking.

Alter boldly to port and pass astern of her In the stated circumstances a power-driven vessel keeps out of the way of a sailing vessel. She is the stand-on vessel and will hold her course, so a bold, early alteration to port takes you clear astern of her. Make it large enough that she sees it at once.

Rule 18 · Responsibilities between vessels · US Coast Guard · International Navigation Rules
Coming up from astern

What is your responsibility?

You are gaining on a slower vessel from directly astern. You have open water to starboard and no other traffic in the exercise.

Keep clear to starboard As the overtaking vessel, you must keep out of the way until finally past and clear. Rule 13 does not prescribe a passing side for this open-water exercise; starboard is the authored clear-water route.

Rule 13 · Overtaking · US Coast Guard · International Navigation Rules
When the give-way vessel does nothing

What do you do first?

Kestrel, a power-driven vessel, is crossing from your port side on a steady bearing. Both vessels are in sight of one another in open water, and you are under power.

Keep your course and speed Rule 17(a)(i): with Kestrel on your port side, you are the stand-on vessel and keep your course and speed, so she can rely on you while she gives way.

Rule 17 · Action by stand-on vessel · US Coast Guard · International Navigation Rules
Crossing a buoyed channel

How do you cross?

You are in a 12 m motor boat, about to cross a buoyed approach channel heading west. Northern Star, a 120 m cargo ship that can navigate safely only within the channel, is coming up it. She is on your port side, on a steady bearing.

Turn to port and run down outside the marks Rule 9(b) and (d): a vessel of less than 20 m, or a vessel crossing, shall not impede the passage of a vessel that can safely navigate only within the channel. Turning to run down outside the starboard-hand marks keeps you out of the channel until she has passed; you then cross astern of her.

Rule 9 · Narrow channels · US Coast Guard · International Navigation Rules
Crossing the traffic lanes

How should you cross the scheme?

You need to get to the far side of a traffic separation scheme. The southbound lane lies ahead, then the separation zone, then the northbound lane. Ostrava is coming down the southbound lane; Lumen is heading north, away from you. Your present heading crosses the lanes diagonally.

Turn to a heading of 090° Rule 10(c): a vessel obliged to cross a traffic lane does so on a heading as nearly as practicable at right angles to the general direction of traffic flow. That minimises the time in the lane and makes your intention obvious.

Rule 10 · Traffic separation schemes · US Coast Guard · International Navigation Rules

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