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Sound Signals Quiz: 10 Real USCG Exam Questions

Whistle blasts and fog signals trip up a lot of people, because there is no diagram to lean on. You just have to know the pattern. Here are 10 sound signals questions 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. Explanations are checked against the 2022 U.S. Coast Guard Navigation Center (NAVCEN) Navigation Rules handbook.

The quiz

Question 1. BOTH INTERNATIONAL & INLAND A "short blast" on the whistle has a duration of __________.

  1. 1 second
  2. 4 to 6 seconds
  3. 8 to 12 seconds
  4. 12 to 15 seconds
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A. 1 second

A short blast is about one second long. A prolonged blast is longer, four to six seconds. Every signal in the Rules is built from those two sounds. See Rule 32(b).

Question 2. BOTH INTERNATIONAL & INLAND The duration of a prolonged blast of the whistle is __________.

  1. 2 to 4 seconds
  2. 4 to 6 seconds
  3. 6 to 8 seconds
  4. 8 to 10 seconds
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B. 4 to 6 seconds

A prolonged blast lasts four to six seconds. Count "one-thousand-one" up to about "four-thousand-four" and you are in the right range. See Rule 32(c).

Question 3. BOTH INTERNATIONAL & INLAND Three short blasts of the whistle means __________.

  1. "danger"
  2. "I am in distress"
  3. the vessel is not under command (broken down)
  4. "I am operating astern propulsion"
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D. "I am operating astern propulsion"

Three short blasts mean "I am operating astern propulsion." Under International rules it applies to a power-driven vessel in sight of another. Under Inland rules it applies when power-driven vessels are meeting or crossing within half a mile. Either way, it is about engines going astern, not about distress or a breakdown. See Rule 34(a).

Question 4. BOTH INTERNATIONAL & INLAND Five or more short blasts on a vessel's whistle indicates that she is __________.

  1. in doubt that another vessel is taking sufficient action to avoid a collision
  2. altering course to starboard
  3. altering course to port
  4. the stand-on vessel and will maintain course and speed
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A. in doubt that another vessel is taking sufficient action to avoid a collision

Five or more short and rapid blasts are the doubt (or danger) signal. A vessel uses it when she is in sight of another vessel and doubts that enough action is being taken to avoid a collision, or does not understand the other vessel's intentions. See Rule 34(d).

Question 5. BOTH INTERNATIONAL & INLAND A power-driven vessel making way through the water sounds which fog signal?

  1. Two short blasts every one minute
  2. One short blast every one minute
  3. Two prolonged blasts every two minutes
  4. One prolonged blast every two minutes
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D. One prolonged blast every two minutes

A power-driven vessel making way through the water in fog sounds one prolonged blast at intervals of not more than two minutes. See Rule 35(a).

Question 6. BOTH INTERNATIONAL & INLAND A power-driven vessel underway in fog making NO way must sound what signal?

  1. One long blast
  2. Two prolonged blasts
  3. One prolonged blast
  4. One prolonged and two short blasts
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B. Two prolonged blasts

Underway but stopped and making no way through the water, a power-driven vessel sounds two prolonged blasts in succession, with about two seconds between them, at intervals of not more than two minutes. See Rule 35(b).

Question 7. BOTH INTERNATIONAL & INLAND A vessel 50 meters in length at anchor must sound which fog signal?

  1. 5-second ringing of a bell every minute
  2. 5-second ringing of a bell every two minutes
  3. 5-second sounding of a gong every minute
  4. 5-second sounding of both a bell and gong every two minutes
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A. 5-second ringing of a bell every minute

A vessel at anchor rings her bell rapidly for about five seconds at intervals of not more than one minute. A gong is added only on vessels 100 meters or more in length, so a 50-meter vessel uses the bell alone. See Rule 35(g).

Question 8. BOTH INTERNATIONAL & INLAND A vessel being towed, if manned, shall sound a fog signal of __________.

  1. two short blasts
  2. three short blasts
  3. one prolonged and two short blasts
  4. one prolonged and three short blasts
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D. one prolonged and three short blasts

A manned vessel being towed sounds one prolonged blast followed by three short blasts at intervals of not more than two minutes. If more than one vessel is towed, the last manned vessel does it, and when practicable right after the towing vessel's signal. See Rule 35(e).

Question 9. BOTH INTERNATIONAL & INLAND What is the identity signal which may be sounded by a vessel engaged on pilotage duty in fog?

  1. 2 short blasts
  2. 3 short blasts
  3. 4 short blasts
  4. 5 short blasts
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C. 4 short blasts

A pilot vessel on pilotage duty may add an identity signal of four short blasts to her normal fog signal. It is optional, so a pilot vessel is never required to sound it. See Rule 35(k).

Question 10. BOTH INTERNATIONAL & INLAND Continuous sounding of a fog whistle by a vessel is a signal __________.

  1. that the vessel is anchored
  2. to request the draw span of a bridge to be opened
  3. of distress
  4. that the vessel is broken down and drifting
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C. of distress

A continuous sounding of any fog-signaling apparatus is a distress signal. If you hear it, a vessel needs help. See Rule 37 and Annex IV, paragraph 1(b).

How did you do?

If you got 9 or 10, your sound signals are in good shape. If you missed a few, read the sound signals guide, then go through Rule 35 one vessel type at a time. Lights are the other big memorization topic, so try the navigation lights quiz next.

Want the rest of the sound signal questions? Practice every whistle, bell and fog signal question in the USCG bank, with missed-question review so the ones you get wrong keep coming back, 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.

What is the difference between a short blast and a prolonged blast?

A short blast is about one second. A prolonged blast is four to six seconds (Rule 32).

Do I need to memorize every fog signal?

You do need the core ones: one prolonged blast every two minutes for a power-driven vessel making way, two prolonged if stopped, a bell at anchor, and one prolonged plus two short for vessels like sailing vessels, fishing vessels and vessels towing. Learn them in that order and add the special cases after.

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