AB Unlimited (Able Seafarer–Unlimited) is the highest category of the Able Seaman deck rating, requiring three years of ocean or Great Lakes deck service. It sits the same national AB written exam as every other AB category — the sea-time bar is what is higher.
36 months (3 years) of deck service on vessels operating on oceans or the Great Lakes (46 CFR 12.403).
$280 in Coast Guard fees — $95 evaluation + $140 exam + $45 issuance, plus the CG-719K medical, drug test, and TWIC.
AB Unlimited is earned with 36 months (3 years) of deck service on vessels operating on oceans or the Great Lakes. It carries the broadest AB scope — any tonnage, any ocean route — which is why the qualifying service is the longest of the categories. The written exam is identical to Special and Limited; because all AB categories share one exam, mariners often certify at a lower category first and raise it to Unlimited on sea time alone.
There is one national AB written exam for every category, so AB Unlimited sits the same test as AB Special, Limited, and Unlimited: two modules of 50 questions each at a 70% pass mark. The Rules of the Road module is closed-book.
Q450 · 50 Q · 70%
Q451 · 50 Q · 70%
Full detail, the six categories, and the Lifeboatman + marlinespike demonstrations are on the Able Seaman hub.
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12 months of deck service on oceans or the navigable waters of the U.S. including the Great Lakes (46 CFR 12.403).
Practice AB Special18 months of deck service on vessels of 100 GRT or more not exclusively confined to rivers and smaller inland lakes (46 CFR 12.403).
Practice AB LimitedAB Unlimited requires 36 months (3 years) of deck service on vessels operating on oceans or the Great Lakes, under 46 CFR 12.403 — the longest service requirement of the AB categories.
No. Every AB category — Special, Limited, Unlimited, OSV, Sail, and Fishing Industry — takes the identical AB01 written exam (Q450 + Q451). Unlimited's higher bar is the required sea service, not the test.
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