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USCG Able Seafarer (AB) Practice Test

88 Able Seafarer (AB) questions from the National Maritime Center’s published sample exams for Able Seafarer (AB) Unlimited, Limited, Special…, each with the NMC’s answer key, across 2 subjects. Questions that need an illustration, a chart or a reference book are left out.

The Coast Guard changed the endorsement's title from Able Seaman to Able Seafarer in 2024 (89 FR 93040).

61 of them come with the closest regulation or reference section, shown with the answer.

Take a quiz of 10 drawn at random, or read the 10 sample questions and answers below.

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10 sample Able Seafarer (AB) questions with answers

The same 10 on every visit. A related section is the closest match RegKnot found in the regulations and references; it is not part of the NMC’s answer key.

  1. Question 1 · Able Seafarer (AB) Unlimited, Limited, Special…

    BOTH INTERNATIONAL & INLAND You are involved in a crossing situation with a vessel off your port bow. The other vessel is showing a high intensity all-round flashing red light. Which action should you take?

    • A.Remain clear of the vessel
    • B.Alter course to starboard
    • C.Maintain course and speed (correct answer)
    • D.Reduce Speed

    Answer: C. Maintain course and speed

    Related regulation: COLREGs Rule 37 — Rule 37: When a vessel is in distress and requires assistance she shall use or exhibit the

  2. Question 2 · Able Seafarer (AB) Unlimited, Limited, Special…

    Under the U.S. Aids to Navigation System, a special mark possesses which of the following characteristics?

    • A.Must be lighted with a fixed or flashing white light
    • B.May show a yellow light with a flashing rhythm (correct answer)
    • C.May show a light with the Morse code "A" rhythm
    • D.Must be lighted with a yellow isophase light

    Answer: B. May show a yellow light with a flashing rhythm

    Further reading: Bowditch Art.830 — Bowditch Ch.8 Short Range Aids to Navigation — 830. IALA Special Marks

  3. Question 3 · Able Seafarer (AB) Unlimited, Limited, Special…

    Which would be considered pollution under the U.S. water pollution laws?

    • A.Oil
    • B.Hazardous substances
    • C.Garbage
    • D.All of the above (correct answer)

    Answer: D. All of the above

    Related regulation: USCG MSM 16000.71 Ch.6 — Marine Safety — Domestic Inspection Programs — Ch.6 POLLUTION PREVENTION

  4. Question 4 · Able Seafarer (AB) Unlimited, Limited, Special…

    How are buoys which mark isolated dangers painted?

    • A.Alternating red and white stripes
    • B.Alternating red and black bands (correct answer)
    • C.Alternating green and white bands
    • D.Alternating green and black bands

    Answer: B. Alternating red and black bands

    Related regulation: 33 CFR 62.29 ↗ — Isolated danger marks

  5. Question 5 · Able Seafarer (AB) Unlimited, Limited, Special…

    INLAND ONLY Which light(s) are permitted ONLY for law enforcement vessels?

    • A.an alternately flashing red and yellow light
    • B.a flashing blue light (correct answer)
    • C.two red lights in a vertical line
    • D.a flashing yellow light

    Answer: B. a flashing blue light

    Related regulation: 33 CFR 88.05 ↗ — Law enforcement vessels

  6. Question 6 · Able Seafarer (AB) Unlimited, Limited, Special…

    Which device is designed to automatically hold the load if power should fail to an electric winch?

    • A.Electromagnetic brake (correct answer)
    • B.Hand brake
    • C.Motor controller
    • D.Pneumatic brake

    Answer: A. Electromagnetic brake

    Related regulation: 29 CFR 1919.22 ↗ — Requirements governing braking devices and power sources

  7. Question 7 · Able Seafarer (AB) Unlimited, Limited, Special…

    How many degrees are there on a compass card?

    • A.360° (correct answer)
    • B.380°
    • C.390°
    • D.420°

    Answer: A. 360°

    Further reading: Bowditch Art.918 — Bowditch Ch.9 Compasses — 918. The Compass and the Binnacle

  8. Question 8 · Able Seafarer (AB) Unlimited, Limited, Special…

    When entering a channel from seaward, which is TRUE concerning the numbers on buoys?

    • A.The numbers are the same as their Light List number
    • B.The numbers decrease with the odd numbers to starboard
    • C.The numbers increase with the even numbers to starboard (correct answer)
    • D.They are marked in 6-inch figures with retro-reflective material

    Answer: C. The numbers increase with the even numbers to starboard

    Related regulation: 33 CFR 62.43 ↗ — Numbers and letters

  9. Question 9 · Able Seafarer (AB) Unlimited, Limited, Special…

    What is an advantage of the magnetic compass aboard vessels?

    • A.All points on the compass rose are readily visible.
    • B.Compass error is negligible at or near the earth's magnetic poles.
    • C.It is reliable due to its essential simplicity. (correct answer)
    • D.It does not have to be checked as often.

    Answer: C. It is reliable due to its essential simplicity.

    Further reading: Bowditch Art.938 — Bowditch Ch.9 Compasses — 938. New Direction Sensing Technologies

  10. Question 10 · Able Seafarer (AB) Unlimited, Limited, Special…

    What is a lighted safe water mark fitted with to aid in its identification?

    • A.A red and white octagon
    • B.Red and white retroreflective material
    • C.A sequential number
    • D.A spherical topmark (correct answer)

    Answer: D. A spherical topmark

    Further reading: Bowditch Art.829 — Bowditch Ch.8 Short Range Aids to Navigation — 829. IALA Safe Water Marks

Exams these questions come from

  • Able Seafarer (AB) Unlimited, Limited, Special…88 questions

Subjects these questions cover

Each subject has its own practice page, with questions from every exam that covers it.

Requirements for the endorsement

More USCG practice tests

The questions and answer keys are from the U.S. Coast Guard National Maritime Center’s published sample exams. RegKnot is not affiliated with the U.S. Coast Guard or the National Maritime Center. A practice score does not predict your exam result; check the NMC for current exam requirements.