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100+ Free USCG AB Limited Practice Questions

Pass your USCG Able Seafarer (Able Seaman) Limited exam on the first try — instant access, no signup required.

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Which of the following is NOT part of the SOLAS abandon-ship preparation 'Bridge Card' protocol?

A
B
C
D
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2026 Statistics

Key Facts: USCG AB Limited Exam

360

Sea Days for Limited (vs 540 Unlimited)

46 CFR 12.401

150

Written Questions Across 3 Modules

USCG NMC Q450/Q451/Q452

70%

Passing Score Each Module

USCG NMC exam structure

10 in 15 min

Knot Practical (4 Mandatory + 6 Chosen)

USCG practical demonstration

$95

Exam Fee

NMC fee schedule

Dec 22, 2026

End of 50% Sea-Service Reduction

NMC Reduced Sea Service for AB FAQ

As of May 2026, Able Seafarer-Limited under 46 CFR 12.401 requires 360 days of qualifying deck service on vessels not exclusively confined to rivers and smaller inland lakes. A temporary 50% sea-service reduction is in effect for AB applications processed between December 22, 2023 and December 22, 2026. The written exam is identical in module structure to AB Unlimited — three 50-question modules with 70% passing — plus a 10-knots-in-15-minutes practical and a lifeboatman demonstration. The endorsement is route-limited to coastwise, Great Lakes, and inland (not Oceans), regardless of vessel tonnage.

Sample USCG AB Limited Practice Questions

Try these sample questions to test your USCG AB Limited exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the COLREGS, which vessel has the highest priority in a stand-on situation?
A.A power-driven vessel underway
B.A vessel engaged in fishing
C.A vessel not under command
D.A sailing vessel
Explanation: The Rule 18 'pecking order' places a vessel not under command at the top of the give-way hierarchy. Other vessels must keep clear of her because she is unable to maneuver as required by the Rules due to exceptional circumstances.
2What is the meaning of one prolonged blast sounded by a power-driven vessel in restricted visibility?
A.I intend to overtake you on your starboard side
B.A power-driven vessel underway making way through the water
C.A vessel at anchor warning of her position
D.I am operating astern propulsion
Explanation: Under Rule 35(a), a power-driven vessel making way through the water sounds one prolonged blast at intervals of not more than two minutes in or near an area of restricted visibility.
3Two power-driven vessels are crossing so as to involve risk of collision. Which vessel is the give-way vessel?
A.The vessel that has the other on her port side
B.The vessel that has the other on her starboard side
C.The smaller of the two vessels
D.The vessel proceeding at higher speed
Explanation: Under Rule 15, when two power-driven vessels are crossing, the vessel that has the other on her own starboard side is the give-way vessel and must, if circumstances permit, avoid crossing ahead of the other.
4A vessel showing two all-round red lights in a vertical line at night is:
A.A vessel constrained by her draft
B.A pilot vessel on station
C.A vessel not under command
D.A vessel engaged in trawling
Explanation: Rule 27(a) requires a vessel not under command to exhibit two all-round red lights in a vertical line where they can best be seen. By day, she shows two black balls in the same arrangement.
5On the Inland Rules, what sound signal is used by a power-driven vessel intending to overtake another on the other vessel's starboard side?
A.One short blast
B.Two short blasts
C.Two prolonged blasts followed by one short blast
D.Two prolonged blasts followed by two short blasts
Explanation: Inland Rule 34(c) requires the overtaking vessel to indicate intention by sounding two prolonged blasts followed by one short blast to overtake on the starboard side, or two prolonged followed by two short to overtake on the port side.
6A red lateral buoy marked '4' under U.S. Aids to Navigation System indicates:
A.Leave the buoy to starboard when returning from sea
B.Leave the buoy to port when returning from sea
C.A safe water mark with no preferred channel
D.An isolated danger to be passed on either side
Explanation: The mnemonic 'red right returning' means a red, even-numbered lateral mark is kept to starboard when proceeding from seaward into a U.S. channel. Green odd-numbered marks are kept to port.
7Under International Rules, a vessel engaged in trawling underway displays which masthead arrangement?
A.Two all-round red lights in a vertical line
B.A green all-round light over a white all-round light
C.A red all-round light over a white all-round light
D.Three all-round red lights in a vertical line
Explanation: Rule 26(b) requires a vessel engaged in trawling to display, when underway, two all-round lights in a vertical line — the upper being green and the lower white — plus sidelights and a sternlight when making way.
8Five or more short and rapid blasts on the whistle in U.S. waters indicates:
A.A passing agreement has been reached
B.Doubt regarding the intent or action of the other vessel
C.Reduced speed in restricted visibility
D.A vessel leaving a slip or berth
Explanation: Under Rule 34(d), when vessels in sight of one another are in doubt that the other is taking sufficient action to avoid collision, the vessel in doubt shall immediately indicate it by at least five short and rapid blasts.
9The primary duty of a lookout is:
A.To assist the helmsman in steering the course
B.To maintain a proper lookout by sight, hearing, and all available means
C.To monitor the radar continuously and report all targets
D.To answer the VHF radio when the watch officer is busy
Explanation: Rule 5 requires every vessel to maintain a proper lookout by sight and hearing as well as by all available means appropriate to the prevailing circumstances. The lookout's sole job is observing and reporting; it should not be combined with helm duty except on small vessels.
10In a narrow channel, a vessel of less than 20 meters in length shall NOT impede the passage of:
A.Any pleasure craft transiting the channel
B.A vessel which can safely navigate only within the channel
C.Any fishing vessel hauling gear
D.Any vessel engaged in dredging operations
Explanation: Rule 9(b) states that a vessel of less than 20 meters in length, or a sailing vessel, shall not impede the passage of a vessel which can safely navigate only within a narrow channel or fairway.

About the USCG AB Limited Exam

The USCG Able Seafarer-Limited endorsement under 46 CFR 12.401 authorizes service as a deck rating on vessels of any tonnage operating on coastwise, Great Lakes, and inland routes (excluding Oceans). The written exam content is identical to AB Unlimited; the distinction is sea service (360 days for Limited vs 540 days for Unlimited) and route restriction. Candidates take three 50-question written modules and complete a practical knot-tying and lifeboatman demonstration.

Assessment

Three 50-question written modules (Q450 Rules of the Road/Nav General, Q451 Deck General & Safety, Q452 Lifeboatman) for 150 total written questions, plus a practical demonstration of 10 knots in 15 minutes and a lifeboatman skills evaluation.

Time Limit

Up to 3.5 hours per module

Passing Score

70% each module

Exam Fee

$95 exam fee; $245 total typical original application (U.S. Coast Guard National Maritime Center (NMC) / Regional Exam Centers)

USCG AB Limited Exam Content Outline

33% (50 questions, 70% to pass)

Rules of the Road / Navigation General

COLREGS and Inland Rules — lookout, risk of collision, steering and sailing rules, lights, shapes, sound signals, narrow channels, traffic separation, aids to navigation, charts, tides, currents, and compass.

33% (50 questions, 70% to pass)

Deck General & Safety

Marlinspike seamanship and knots, anchoring, mooring and line handling, stability and free-surface, cargo gear inspection, firefighting, enclosed-space entry, damage control, MARPOL, and heavy weather.

34% (50 questions, 70% to pass)

Lifeboatman

Lifeboat and liferaft launching, on-load release, SOLAS equipment outfits (Pack A/B), HRUs, painters, sea anchors, EPIRBs, SARTs, pyrotechnic distress signals, hypothermia, HELP/huddle, and abandon-ship drills.

How to Pass the USCG AB Limited Exam

What You Need to Know

  • Passing score: 70% each module
  • Assessment: Three 50-question written modules (Q450 Rules of the Road/Nav General, Q451 Deck General & Safety, Q452 Lifeboatman) for 150 total written questions, plus a practical demonstration of 10 knots in 15 minutes and a lifeboatman skills evaluation.
  • Time limit: Up to 3.5 hours per module
  • Exam fee: $95 exam fee; $245 total typical original application

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

USCG AB Limited Study Tips from Top Performers

1Drill COLREGS lights, shapes, and sound signals until you can identify the vessel type instantly from the description.
2Memorize Rule 18's pecking order so you know which vessel gives way in every encounter type before you read the answers.
3Tie the four mandatory knots (bowline, square knot, clove hitch, sheet bend) every day for two weeks until each one is muscle memory.
4Pick six additional knots — rolling hitch, figure eight, round turn with two half hitches, double sheet bend, anchor bend, timber hitch — and practice them in rotation for the practical exam.
5Map MARPOL Annex I (oil), Annex IV (sewage), Annex V (garbage), and Annex VI (air) onto specific overboard-discharge rules so pollution questions are quick recall.
6Study lifeboat and liferaft launching as a sequence: gripes off, tricing pendants, bowsing tackles, lower, on-load release, then engine start — order matters in exam scenarios.
7Practice timed sets of 50 questions per module to match REC pacing and to build the discipline to flag and move past stubborn items.
8Build a one-page emergency-action checklist (fire, flooding, man overboard, grounding, abandon ship) so safety questions are answered consistently.

Frequently Asked Questions

How is Able Seafarer-Limited different from Able Seafarer-Unlimited?

Under 46 CFR 12.401 the written exam content and the practical demonstration are identical for both. The differences are sea-service requirement and route. Limited requires 360 qualifying days and is valid on vessels of any tonnage on coastwise, Great Lakes, and inland routes (excluding Oceans); Unlimited requires 540 days and adds the Oceans route.

How many sea days do I need for AB Limited?

The standard requirement under 46 CFR 12.401 is 360 days of qualifying deck service on vessels not exclusively confined to the rivers and smaller inland lakes of the United States. The Coast Guard has also implemented a temporary 50% sea-service reduction for AB applications processed between December 22, 2023 and December 22, 2026 — verify the current reduction window with NMC before applying.

How many questions are on the written exam?

The AB Limited written exam is 150 questions across three 50-question modules — Rules of the Road & Navigation General (Q450), Deck General & Safety (Q451), and Lifeboatman (Q452). Each module is scored independently and requires 70% (35 correct of 50) to pass.

Is there a practical exam in addition to the written?

Yes. Candidates must demonstrate 10 knots in 15 minutes including four mandatory knots (bowline, square knot, clove hitch, sheet bend) plus six additional knots chosen by the evaluator. A lifeboatman practical demonstration covers launching, righting (where applicable), equipment, and survival craft operations.

How much does the AB Limited exam cost?

The current NMC fee schedule lists a $95 examination fee. A typical original deck-rating application totals roughly $245 ($100 evaluation + $95 exam + $50 issuance), plus the cost of any USCG-approved Lifeboatman course required to obtain the endorsement.

Where do I take the exam?

AB Limited written exams are administered at U.S. Coast Guard Regional Exam Centers (RECs) on a scheduled basis. Schedule through the NMC ASAP application portal. Remote testing is not available for this endorsement.

What study path makes the highest-leverage use of time?

Rules of the Road & Nav General usually carries the broadest content range, so allocate the most prep time there. Deck General & Safety is the second-largest block (knots, anchoring, stability, firefighting, MARPOL). Then drill Lifeboatman procedures and the practical knot list until every required knot is automatic.