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Restricted Visibility Quiz: 10 Real USCG Exam Questions

Fog changes the game. There's no stand-on vessel, your radar contacts aren't "in sight," and the turn that feels natural can be the wrong one. Here are 10 questions on conduct in restricted visibility (Rule 19), pulled word for word from the USCG Rules of the Road question bank. Answer each one in your head, then tap "Show answer" to check yourself and see the rule behind it.

Every question here applies under both International and Inland rules, and none need a diagram. Explanations are checked against the rule text in the U.S. Coast Guard Navigation Center (NAVCEN) Navigation Rules handbook. Rule 19 is the same in substance under Inland, and the Rule 19 page walks through it. For the fog signals themselves, see the Rule 35 page and the sound signals quiz.

The quiz

Question 1. BOTH INTERNATIONAL & INLAND The steering and sailing rules for vessels in restricted visibility apply to vessels __________.

  1. in sight of one another in fog
  2. navigating in or near an area of restricted visibility
  3. only if they are showing special purpose lights
  4. only if they have operational radar
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B. navigating in or near an area of restricted visibility

Rule 19 applies to vessels not in sight of one another when navigating in or near an area of restricted visibility. So you don't have to be inside the fog bank for it to kick in, and once two vessels can see each other, the in-sight rules take over. See Rule 19(a).

Question 2. BOTH INTERNATIONAL & INLAND The term "restricted visibility" as used in the Rules refers __________.

  1. only to fog
  2. only to visibility of less than one-half of a mile
  3. to visibility where you cannot see shore
  4. to any condition where visibility is restricted
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D. to any condition where visibility is restricted

Restricted visibility means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or any other similar causes. The Rules set no distance like half a mile. See Rule 3(l).

Question 3. BOTH INTERNATIONAL & INLAND You are on watch in fog. Which vessel is "in sight"?

  1. A vessel that you can see from the bridge
  2. A radar target of which you have determined the course and speed
  3. A vessel from which you can hear the fog signal
  4. All of the above
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A. A vessel that you can see from the bridge

Vessels are in sight of one another only when one can be observed visually from the other. A radar contact or a fog signal you can hear doesn't count, which is why Rule 19 still governs a vessel you've plotted but can't see. See Rule 3(k).

Question 4. BOTH INTERNATIONAL & INLAND When navigating in restricted visibility, a power-driven vessel shall __________.

  1. stop her engines when hearing a fog signal forward of her beam, even if risk of collision does not exist
  2. have her engines ready for immediate maneuver
  3. when making way, sound one prolonged blast at intervals of not more than one minute
  4. operate at a speed to be able to stop in the distance of her visibility
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B. have her engines ready for immediate maneuver

Every vessel proceeds at a safe speed adapted to the conditions, and a power-driven vessel shall have her engines ready for immediate maneuver. Answer A goes too far: Rule 19(e) says reduce speed to the minimum needed to keep on course, not stop engines, and not when risk of collision has been ruled out. Answer C has the wrong interval, since Rule 35(a) says not more than 2 minutes. See Rule 19(b).

Question 5. BOTH INTERNATIONAL & INLAND What is required of a vessel navigating near an area of restricted visibility?

  1. A power-driven vessel shall have her engines ready for immediate maneuver.
  2. She must sound appropriate sound signals.
  3. If she detects another vessel by radar, she shall determine if risk of collision exists.
  4. All of the above
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D. All of the above

All three. Rule 19 covers vessels in or near an area of restricted visibility, so engines ready (19(b)) and the radar duty to determine whether risk of collision exists (19(d)) apply there too. Rule 35 fog signals are also used in or near an area of restricted visibility, by day or night. See Rule 19.

Question 6. BOTH INTERNATIONAL & INLAND By radar alone, you detect a vessel ahead on a collision course, about 3 miles distant. Your radar plot shows this to be a meeting situation. You should __________.

  1. turn to port
  2. turn to starboard
  3. maintain course and speed and sound the danger signal
  4. maintain course and speed and sound no signal
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B. turn to starboard

Detected by radar alone, the other vessel is not in sight, so the head-on rule doesn't apply and there is no passing signal to sound. Rule 19(d) says take avoiding action in ample time and, if you alter course, avoid a turn to port for a vessel forward of the beam (other than one being overtaken). That leaves a turn to starboard. See Rule 19(d)(i).

Question 7. BOTH INTERNATIONAL & INLAND In restricted visibility, a vessel which detects by radar alone the presence of another vessel shall determine if a close quarters situation is developing or risk of collision exists. If so, she shall __________.

  1. sound the danger signal
  2. when taking action, make only course changes
  3. avoid altering course toward a vessel abaft the beam
  4. All of the above
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C. avoid altering course toward a vessel abaft the beam

When an alteration of course is the avoiding action, Rule 19(d)(ii) says avoid altering course towards a vessel abeam or abaft the beam. The danger signal in answer A is a Rule 34(d) signal for vessels in sight of one another, and nothing limits you to course changes only. See Rule 19(d)(ii).

Question 8. BOTH INTERNATIONAL & INLAND What is TRUE when operating in fog and other vessels are detected by radar?

  1. You should make an ample change to port for a vessel crossing on the starboard bow.
  2. You should maneuver in ample time if a close-quarters situation is developing.
  3. You should determine the course and speed of all radar contacts at six minute intervals.
  4. Long-range scanning will provide early warning of ALL other vessels within the radar's range.
Show answer

B. You should maneuver in ample time if a close-quarters situation is developing.

If radar shows a close-quarters situation developing or risk of collision, take avoiding action in ample time. Answer A is the classic trap: for a vessel forward of the beam, Rule 19(d)(i) says avoid turning to port. The Rules set no six-minute plotting interval. See Rule 19(d).

Question 9. BOTH INTERNATIONAL & INLAND You hear the fog signal of another vessel forward of your beam. Risk of collision may exist. You MUST __________.

  1. begin a radar plot
  2. stop your engines
  3. take all way off, if necessary
  4. All of the above
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C. take all way off, if necessary

Unless risk of collision has been ruled out, a vessel that hears a fog signal apparently forward of her beam reduces speed to the minimum at which she can be kept on course, takes all her way off if necessary, and navigates with extreme caution until the danger is over. Stopping engines and starting a radar plot are not what the rule requires. See Rule 19(e).

Question 10. BOTH INTERNATIONAL & INLAND Which statement concerning maneuvering in restricted visibility is FALSE?

  1. A vessel which cannot avoid a close-quarters situation with a vessel forward of her beam shall reduce her speed to bare steerageway.
  2. A vessel which hears a fog signal forward of her beam shall stop her engines.
  3. A vessel which hears a fog signal forward of the beam shall navigate with caution.
  4. If a vessel determines by radar that a close-quarters situation is developing, she shall take avoiding action in ample time.
Show answer

B. A vessel which hears a fog signal forward of her beam shall stop her engines.

Answer B is the false one. Rule 19(e) doesn't say stop your engines. It says reduce to the minimum speed at which you can keep your course, take all way off if necessary, and navigate with extreme caution. A and C come from Rule 19(e), and D comes from Rule 19(d). See Rule 19(e).

How did you do?

If you got 9 or 10, you know how to handle yourself in the fog. If you missed a few, go back over the Rule 19 page, then the safe speed and risk of collision pages, since those rules apply in any visibility. Then try the COLREGS practice test for a mixed set. Want another topic? Take the sound signals quiz, the safe speed and narrow channels quiz, the right of way quiz, the navigation lights quiz, or the towing lights quiz.

Want the rest of the fog questions? Practice all 1,272 USCG questions, with missed-question review, in COLREGS: Rules of the Road for iPhone and iPad. Download on the App Store

Prefer the browser? The free web study tool has all 1,272 questions.

Frequently asked questions

Are these real USCG exam questions?

Yes. All 10 come word for word from the USCG Rules of the Road question bank, the same 1,272 questions used in COLREGS Prep.

How many restricted visibility questions are in the question bank?

In COLREGS Prep, only 1 question is tagged to Rule 19 itself, but 173 are tagged to Rule 35 (sound signals in restricted visibility): 158 apply under both rule sets, 11 are International only, and 4 are Inland only. Many of the Rule 35 questions actually test Rule 19 conduct, like what to do when you hear a fog signal forward of the beam. A rule tag is a rough guide, and this quiz mixes both.

Is there a stand-on vessel in fog?

Not when vessels are out of sight of one another. Rule 19 gives every vessel the same duties: safe speed, engines ready, and early avoiding action. The stand-on and give-way rules in Rules 11 to 18 apply only to vessels in sight of one another.

Which way should I turn for a radar contact in fog?

If you alter course, Rule 19(d) says avoid a turn to port for a vessel forward of the beam (other than one being overtaken), and avoid turning towards a vessel abeam or abaft the beam. For a contact ahead or on the bow, that usually means a turn to starboard.

What should I do when I hear a fog signal forward of the beam?

Unless you've determined that risk of collision does not exist, Rule 19(e) says reduce speed to the minimum at which you can keep your course, take all way off if necessary, and navigate with extreme caution until the danger of collision is over.

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