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Towing Lights Quiz: 10 Real USCG Exam Questions

Towing lights are one of the biggest topics on the Rules of the Road exam, and the counting trips people up. Two masthead lights or three? Where does the tow length start? Which shapes go on the tug and which on the tow? Here are 10 questions on Rule 24, 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. Inland has its own twists for pushing ahead and towing alongside, like two towing lights instead of a sternlight, and the Rule 24 page spells them out.

The quiz

Question 1. BOTH INTERNATIONAL & INLAND A power-driven vessel, when towing astern, shall show __________.

  1. two towing lights in a vertical line
  2. a towing light in a vertical line above the stern light
  3. two towing lights in addition to the stern light
  4. a small white light in lieu of the stern light
Show answer

B. a towing light in a vertical line above the stern light

A towing vessel with her tow astern shows a yellow towing light in a vertical line above the sternlight. Not two towing lights, and not in place of the sternlight. See Rule 24(a)(iv).

Question 2. BOTH INTERNATIONAL & INLAND A towing light is a yellow light having the same characteristics as a(n) __________.

  1. special flashing light
  2. anchor light
  3. stern light
  4. masthead light
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C. stern light

A towing light is a yellow light with the same characteristics as the sternlight, so it shows over an arc of 135 degrees, 67.5 degrees from right aft on each side. See Rule 21(d).

Question 3. BOTH INTERNATIONAL & INLAND A 20-meter vessel is towing another vessel astern. The length of the tow from the stern of the towing vessel to the stern of the tow is 75 meters. How many white towing masthead lights shall the towing vessel show at night?

  1. 1
  2. 2
  3. 3
  4. 4
Show answer

B. 2

When the tow is 200 meters or less, measured from the stern of the towing vessel to the after end of the tow, she shows two masthead lights in a vertical line. A 75-meter tow is well under that. See Rule 24(a)(i).

Question 4. BOTH INTERNATIONAL & INLAND A towing vessel is towing two barges astern. The length of the tow from the stern of the tug to the stern of the last barge is 250 meters. The towing vessel is 45 meters in length. How many white masthead lights should be displayed on the tugboat at night?

  1. 1
  2. 2
  3. 3
  4. 4
Show answer

C. 3

Once the tow exceeds 200 meters, the towing vessel shows three masthead lights in a vertical line. The 250 meters is measured from the tug's stern, so it counts. Her own length of 45 meters only matters for whether she also needs an after masthead light, which Rule 23 requires at 50 meters or more. See Rule 24(a)(i).

Question 5. BOTH INTERNATIONAL & INLAND A power driven vessel when towing and the length of the tow exceeds 200 meters shall exhibit during daylight hours where they can best be seen which of the following shapes?

  1. a diamond shape
  2. two cones, apexes together
  3. a black ball
  4. one cone, apex upward
Show answer

A. a diamond shape

When the length of the tow exceeds 200 meters, the towing vessel shows a diamond shape where it can best be seen. The two cones with apexes together belong to a vessel engaged in fishing. See Rule 24(a)(v).

Question 6. BOTH INTERNATIONAL & INLAND A vessel being towed astern, where the length of the tow exceeds 200 meters, will exhibit __________.

  1. two balls in a vertical line
  2. a diamond shape where it can best be seen
  3. a ball on each end of the tow
  4. no day-shape
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B. a diamond shape where it can best be seen

The vessel being towed gets a diamond too when the tow is over 200 meters, so a long tow is marked at both ends of the towline by day. See Rule 24(e)(iii).

Question 7. BOTH INTERNATIONAL & INLAND A vessel being towed astern shall show at night __________.

  1. the lights required for a power-driven vessel underway
  2. only the required masthead lights
  3. a stern light only
  4. sidelights and a stern light
Show answer

D. sidelights and a stern light

A vessel or object being towed (other than one covered by Rule 24(g)) shows sidelights and a sternlight. No masthead lights, since she isn't under her own power. See Rule 24(e).

Question 8. BOTH INTERNATIONAL & INLAND Two barges are being pushed ahead by a tugboat. Which statement is TRUE concerning lights on the barges?

  1. Each vessel should show sidelights.
  2. Each vessel should show at least one white light.
  3. The barges should be lighted as separate units.
  4. The barges should be lighted as one vessel.
Show answer

D. The barges should be lighted as one vessel.

Any number of vessels pushed ahead in a group are lighted as one vessel. The lead barge shows sidelights at the forward end. See Rule 24(f). Inland adds a special flashing yellow light at the forward end (Inland 24(f)).

Question 9. BOTH INTERNATIONAL & INLAND A towing vessel pushing a barge ahead and rigidly connected in a composite unit shall show the lights of __________.

  1. a vessel pushing ahead
  2. a power-driven vessel, not towing
  3. a barge being pushed ahead
  4. either answer A or answer B
Show answer

B. a power-driven vessel, not towing

When the pusher and the barge are rigidly connected in a composite unit, they are regarded as one power-driven vessel and show the lights in Rule 23, not towing lights. See Rule 24(b).

Question 10. BOTH INTERNATIONAL & INLAND A partly submerged vessel or object being towed, which is not readily noticeable, shall show __________.

  1. yellow lights at each end
  2. two red lights in a vertical line
  3. a black ball
  4. a diamond shape
Show answer

D. a diamond shape

A partly submerged vessel or object that's hard to see shows a diamond shape at or near the aftermost extremity of the last vessel or object towed. Its lights are all-round white lights, not yellow ones, so answer A is a trap. See Rule 24(g).

How did you do?

If you got 9 or 10, you can read a tow at night. If you missed a few, go back over the Rule 24 page and the navigation lights cheat sheet. Then try the navigation lights quiz for a wider mix of lights, or the COLREGS practice test. Want another topic? Take the right of way quiz, the sound signals quiz, or the safe speed and narrow channels quiz.

Want the rest of the towing 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 towing questions are in the question bank?

In COLREGS Prep, 174 questions are tagged to Rule 24 (towing and pushing): 133 apply under both rule sets, 22 are Inland only, and 19 are International only. It's the second most tagged lights rule in the bank. A rule tag is a rough guide, since some towing questions are tagged to Rules 21, 23, or 27 instead.

How many masthead lights does a towing vessel show?

Towing astern, she shows two masthead lights in a vertical line when the tow is 200 meters or less, and three when it exceeds 200 meters, measured from her stern to the after end of the tow (Rule 24(a)(i)). A towing vessel of 50 meters or more also shows an after masthead light.

What color is a towing light?

Yellow. Rule 21(d) defines it as a yellow light with the same characteristics as the sternlight, and Rule 24(a)(iv) puts it in a vertical line above the sternlight.

Are towing lights different under Inland Rules?

Yes, mainly for pushing ahead and towing alongside. Inland 24(c) shows two towing lights in a vertical line instead of a sternlight, Inland 24(f) adds a special flashing light at the forward end of a vessel pushed ahead or towed alongside, and Inland 24(j) has a Western Rivers exception with no masthead lights.

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