AB Practice Test

The AB Able Seaman exam is taken by mariners seeking an Able Seaman endorsement on a U.S. Merchant Mariner Credential, tested through the U.S. Coast Guard National Maritime Center. This page gives you free practice sets on deck safety, rules of the road, stability, lifesaving, firefighting and seamanship, plus worked answers, a study plan and answers to common questions.

AB Exam at a Glance

What the AB is and how it works

According to U.S. Coast Guard National Maritime Center (NMC), under 46 CFR Parts 10 and 12, “Unless otherwise approved in advance, all retests will be done at a Regional Examination Center.”^[1]

The Able Seaman exam is part of the credentialing process run by the U.S. Coast Guard National Maritime Center (NMC) under 46 CFR Parts 10 and 12. It checks whether a candidate has the deck knowledge needed for an Able Seaman endorsement.

Delivery. The exam is taken in person at a Coast Guard Regional Examination Center (REC). An approved course can be used in place of the exam. Retests are normally done at an REC unless the Coast Guard approves otherwise in advance.

Scoring. The passing score is 70 on each module, so a strong result in one module does not make up for a weak one in another.

Retakes. You can retest at any time, but after a third failure you must wait 90 days before testing again. All examinations and retests must be finished within 1 year of approval for examination.

Validity and renewal. A Merchant Mariner Credential is valid for 5 years. To renew, you can show 1 year of sea service in the past 5 years, or use an alternative such as an open-book exercise or a refresher course.

Module names, question counts and some application details are not listed here. Requirements can change and may depend on your specific endorsement, so check the NMC and your REC before you apply. Our practice questions are written with AI tools and are not real exam questions.

Worked examples: how to reason through AB questions

These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.

Example 1

Question: Which of the following structural members are considered the 'ribs' of the ship, providing the primary transverse strength to the hull?

1. Longitudinals
2. Girders
3. Frames
4. Stanchions

Answer: C. Frames

Explanation:

Frames are the correct answer. They are the transverse ribs attached to the keel, and they give the hull its shape and its main strength against water pressure on the shell plating.

Longitudinals are wrong because they run along the length of the ship, so they give lengthwise strength rather than transverse strength. Girders are heavy supporting members, not the ribs of the hull. Stanchions are vertical pillars that support decks and do not form the side structure.

Rule to remember: ribs that run across the ship are frames, and members that run fore and aft are longitudinals. When a question mentions transverse strength, think frames first.

Example 2

Question: A 'backing' wind shifts in which direction?

1. Counterclockwise (e.g., S to E)
2. Clockwise (e.g., S to W)
3. Northward only
4. Southward only

Answer: A. Counterclockwise (e.g., S to E)

Explanation:

A backing wind shifts counterclockwise, for example from south to east. This is often a sign of deteriorating weather or an approaching frontal system, which is why watchkeepers pay attention to it.

Clockwise is wrong because that describes the opposite shift, a veering wind. Northward only and southward only are wrong because wind shifts are described by the direction of rotation on the compass, not by moving toward a single compass direction.

Rule to remember: backing is counterclockwise, veering is clockwise. Check the wind direction at each observation and note which way it is turning, not just where it points.

Example 3

Question: What is the purpose of a 'painter' on a lifeboat or rescue boat?

1. To mark the boat with identification numbers
2. To secure the boat to the ship's side for lowering
3. To tow or secure the survival craft to the vessel
4. To attach the sea anchor

Answer: C. To tow or secure the survival craft to the vessel

Explanation:

The painter is a line used to tow or temporarily secure a lifeboat or rescue boat to the parent vessel. That is the correct answer.

Marking the boat with identification numbers is wrong because that is done with painted or fixed markings on the boat, not with a line. Securing the boat to the ship's side for lowering is wrong because the painter is not the lowering gear. It keeps the boat connected to the vessel, and does not do the work of lowering it. Attaching the sea anchor is wrong because the sea anchor has its own line.

Rule to remember: match each piece of survival craft equipment to its single job. The painter connects the boat to the vessel.

How to use these practice tests

Start with the official material. Read the NMC exam information for your endorsement and note which modules you will sit, then use this page to find your weak areas.

Take a practice set cold, with no notes, and write down every question you missed or guessed. For each miss, read the explanation and then find the same point in your reference book or the regulations. Do not just memorise the letter of the answer, because the real exam will word things differently.

Give extra time to the topics where a wrong answer can hurt you most. Rules of the road, deck safety, stability and lifesaving each reward understanding over recall, so explain the rule aloud in your own words. For knots and line handling, practise with real rope, since reading about a bend is not the same as tying it.

Repeat sets until your results are steady rather than lucky. Keep in mind that the passing score is 70 on each module, so spread your time across all modules instead of polishing your best one.

In the last days before your appointment, review your list of missed questions, rest, and confirm the details of your REC visit with the Coast Guard.

Sources & last verified

1. U.S. Coast Guard National Maritime Center (NMC), under 46 CFR Parts 10 and 12 — passing score, delivery (official source). “Q451- Deck General/Safety 50 70” Verified Oct 21, 2026.
2. ecfr.gov — retake policy (official source). “However, an applicant who fails an examination for the third time must wait 90 days before re-testing. All examinations and retests must be completed within…” Verified Oct 24, 2026 · source checked Oct 24, 2026.
3. ecfr.gov — validity (official source). “(a) An MMC is valid for a term of 5 years from the date of issuance.” Verified Oct 24, 2026 · source checked Oct 24, 2026.
4. ecfr.gov — renewal (official source). “(i) Provide evidence of at least 1 year of sea service during the past 5 years; (ii) Pass a comprehensive, open-book exercise covering the general…” Verified Oct 24, 2026 · source checked Oct 24, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.